Module java.sql
Package java.sql

Interface Connection接口连接

All Superinterfaces:所有超级界面：
AutoCloseable, Wrapper
public interface Connection extends Wrapper, AutoCloseable

A connection (session) with a specific database. 使用特定数据库的连接（会话）。SQL statements are executed and results are returned within the context of a connection.在连接上下文中执行SQL语句并返回结果。

A Connection object's database is able to provide information describing its tables, its supported SQL grammar, its stored procedures, the capabilities of this connection, and so on. Connection对象的数据库能够提供描述其表、支持的SQL语法、存储过程、此连接的功能等的信息。This information is obtained with the getMetaData method. 此信息是通过getMetaData方法获得的。

Note: When configuring a Connection, JDBC applications should use the appropriate Connection method such as setAutoCommit or setTransactionIsolation. 注意：配置Connection时，JDBC应用程序应使用适当的Connection方法，如setAutoCommit或setTransactionIsolation。Applications should not invoke SQL commands directly to change the connection's configuration when there is a JDBC method available. 当存在可用的JDBC方法时，应用程序不应直接调用SQL命令来更改连接的配置。By default a Connection object is in auto-commit mode, which means that it automatically commits changes after executing each statement. 默认情况下，Connection对象处于自动提交模式，这意味着它在执行每个语句后自动提交更改。If auto-commit mode has been disabled, the method commit must be called explicitly in order to commit changes; otherwise, database changes will not be saved. 如果已禁用自动提交模式，则必须显式调用方法commit以提交更改；否则，将不会保存数据库更改。

A new Connection object created using the JDBC 2.1 core API has an initially empty type map associated with it. 使用JDBC 2.1核心API创建的新Connection对象最初有一个空的类型映射。A user may enter a custom mapping for a UDT in this type map. 用户可以在这个类型映射中为UDT输入自定义映射。When a UDT is retrieved from a data source with the method ResultSet.getObject, the getObject method will check the connection's type map to see if there is an entry for that UDT. 当使用ResultSet.getObject方法从数据源检索UDT时，getObject方法将检查连接的类型映射，以查看是否存在该UDT的条目。If so, the getObject method will map the UDT to the class indicated. 如果是这样，getObject方法将把UDT映射到指定的类。If there is no entry, the UDT will be mapped using the standard mapping. 如果没有条目，UDT将使用标准映射进行映射。

A user may create a new type map, which is a java.util.Map object, make an entry in it, and pass it to the java.sql methods that can perform custom mapping. 用户可以创建一个新的类型映射（java.util.Map对象），在其中创建一个条目，并将其传递给java.sql方法，它可以执行自定义映射。In this case, the method will use the given type map instead of the one associated with the connection. 在这种情况下，该方法将使用给定的类型映射，而不是与连接关联的类型映射。

For example, the following code fragment specifies that the SQL type ATHLETES will be mapped to the class Athletes in the Java programming language. 例如，下面的代码片段指定SQL类型ATHLETES将映射到Java编程语言中的类Athletes。The code fragment retrieves the type map for the Connection object con, inserts the entry into it, and then sets the type map with the new entry as the connection's type map.代码片段检索Connection对象con的类型映射，将条目插入其中，然后将带有新条目的类型映射设置为连接的类型映射。 

      java.util.Map map = con.getTypeMap();
      map.put("mySchemaName.ATHLETES", Class.forName("Athletes"));
      con.setTypeMap(map);
Since:始于：
1.1
See Also:参阅：
DriverManager.getConnection(java.lang.String, java.util.Properties), Statement, ResultSet, DatabaseMetaData

  • Field Summary字段摘要

    Fields字段
    Modifier and Type修饰符和类型
    Field字段
    Description描述
    static int
    TRANSACTION_NONE
    A constant indicating that transactions are not supported.指示不支持事务的常量。
    static int
    TRANSACTION_READ_COMMITTED
    A constant indicating that dirty reads are prevented; non-repeatable reads and phantom reads can occur.指示防止脏读的常数；可能发生不可重复读取和幻象读取。
    static int
    TRANSACTION_READ_UNCOMMITTED
    A constant indicating that dirty reads, non-repeatable reads and phantom reads can occur.一个常量，指示可能发生脏读、不可重复读和幻象读。
    static int
    TRANSACTION_REPEATABLE_READ
    A constant indicating that dirty reads and non-repeatable reads are prevented; phantom reads can occur.指示防止脏读和不可重复读的常数；可能发生幻象读取。
    static int
    TRANSACTION_SERIALIZABLE
    A constant indicating that dirty reads, non-repeatable reads and phantom reads are prevented.一个常量，指示阻止脏读、不可重复读和幻象读。

  • Method Summary方法摘要

    Modifier and Type修饰符和类型
    Method方法
    Description描述
    void
    abort​(Executor executor)
    Terminates an open connection.终止打开的连接。
    default void
    beginRequest()
    Hints to the driver that a request, an independent unit of work, is beginning on this connection.向驱动程序提示一个请求，一个独立的工作单元，正在这个连接上开始。
    void
    clearWarnings()
    Clears all warnings reported for this Connection object.清除为此Connection对象报告的所有警告。
    void
    close()
    Releases this Connection object's database and JDBC resources immediately instead of waiting for them to be automatically released.立即释放此Connection对象的数据库和JDBC资源，而不是等待它们自动释放。
    void
    commit()
    Makes all changes made since the previous commit/rollback permanent and releases any database locks currently held by this Connection object.使自上次提交/回滚以来所做的所有更改永久化，并释放此Connection对象当前持有的所有数据库锁。
    Array
    createArrayOf​(String typeName, Object[] elements)
    Factory method for creating Array objects.用于创建数组对象的工厂方法。
    Blob
    createBlob()
    Constructs an object that implements the Blob interface.构造一个实现Blob接口的对象。
    Clob
    createClob()
    Constructs an object that implements the Clob interface.构造一个实现Clob接口的对象。
    NClob
    createNClob()
    Constructs an object that implements the NClob interface.构造实现NClob接口的对象。
    SQLXML
    createSQLXML()
    Constructs an object that implements the SQLXML interface.构造一个实现SQLXML接口的对象。
    Statement
    createStatement()
    Creates a Statement object for sending SQL statements to the database.创建用于向数据库发送SQL语句的Statement对象。
    Statement
    createStatement​(int resultSetType, int resultSetConcurrency)
    Creates a Statement object that will generate ResultSet objects with the given type and concurrency.创建一个Statement对象，该对象将生成具有给定类型和并发性的ResultSet对象。
    Statement
    createStatement​(int resultSetType, int resultSetConcurrency, int resultSetHoldability)
    Creates a Statement object that will generate ResultSet objects with the given type, concurrency, and holdability.创建一个Statement对象，该对象将生成具有给定类型、并发性和可保持性的ResultSet对象。
    Struct
    createStruct​(String typeName, Object[] attributes)
    Factory method for creating Struct objects.用于创建结构对象的工厂方法。
    default void
    endRequest()
    Hints to the driver that a request, an independent unit of work, has completed.向驱动程序提示请求（一个独立的工作单元）已完成。
    boolean
    getAutoCommit()
    Retrieves the current auto-commit mode for this Connection object.检索此Connection对象的当前自动提交模式。
    String
    getCatalog()
    Retrieves this Connection object's current catalog name.检索此Connection对象的当前目录名称。
    Properties
    getClientInfo()
    Returns a list containing the name and current value of each client info property supported by the driver.返回一个列表，其中包含驱动程序支持的每个客户端信息属性的名称和当前值。
    String
    getClientInfo​(String name)
    Returns the value of the client info property specified by name.返回由名称指定的客户端信息属性的值。
    int
    getHoldability()
    Retrieves the current holdability of ResultSet objects created using this Connection object.检索使用此Connection对象创建的ResultSet对象的当前可保持性。
    DatabaseMetaData
    getMetaData()
    Retrieves a DatabaseMetaData object that contains metadata about the database to which this Connection object represents a connection.检索DatabaseMetaData对象，该对象包含有关此Connection对象表示连接的数据库的元数据。
    int
    getNetworkTimeout()
    Retrieves the number of milliseconds the driver will wait for a database request to complete.检索驱动程序等待数据库请求完成的毫秒数。
    String
    getSchema()
    Retrieves this Connection object's current schema name.检索此Connection对象的当前架构名称。
    int
    getTransactionIsolation()
    Retrieves this Connection object's current transaction isolation level.检索此Connection对象的当前事务隔离级别。
    Map<String,​Class<?>>
    getTypeMap()
    Retrieves the Map object associated with this Connection object.检索与此Connection对象关联的Map对象。
    SQLWarning
    getWarnings()
    Retrieves the first warning reported by calls on this Connection object.检索此Connection对象上的调用报告的第一个警告。
    boolean
    isClosed()
    Retrieves whether this Connection object has been closed.检索此Connection对象是否已关闭。
    boolean
    isReadOnly()
    Retrieves whether this Connection object is in read-only mode.检索此Connection对象是否处于只读模式。
    boolean
    isValid​(int timeout)
    Returns true if the connection has not been closed and is still valid.如果连接尚未关闭且仍然有效，则返回true。
    String
    nativeSQL​(String sql)
    Converts the given SQL statement into the system's native SQL grammar.将给定的SQL语句转换为系统的本机SQL语法。
    CallableStatement
    prepareCall​(String sql)
    Creates a CallableStatement object for calling database stored procedures.创建用于调用数据库存储过程的CallableStatement对象。
    CallableStatement
    prepareCall​(String sql, int resultSetType, int resultSetConcurrency)
    Creates a CallableStatement object that will generate ResultSet objects with the given type and concurrency.创建CallableStatement对象，该对象将生成具有给定类型和并发性的ResultSet对象。
    CallableStatement
    prepareCall​(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability)
    Creates a CallableStatement object that will generate ResultSet objects with the given type and concurrency.创建CallableStatement对象，该对象将生成具有给定类型和并发性的ResultSet对象。
    PreparedStatement
    prepareStatement​(String sql)
    Creates a PreparedStatement object for sending parameterized SQL statements to the database.创建PreparedStatement对象，用于将参数化SQL语句发送到数据库。
    PreparedStatement
    prepareStatement​(String sql, int autoGeneratedKeys)
    Creates a default PreparedStatement object that has the capability to retrieve auto-generated keys.创建一个默认PreparedStatement对象，该对象能够检索自动生成的键。
    PreparedStatement
    prepareStatement​(String sql, int[] columnIndexes)
    Creates a default PreparedStatement object capable of returning the auto-generated keys designated by the given array.创建一个默认PreparedStatement对象，该对象能够返回由给定数组指定的自动生成的键。
    PreparedStatement
    prepareStatement​(String sql, int resultSetType, int resultSetConcurrency)
    Creates a PreparedStatement object that will generate ResultSet objects with the given type and concurrency.创建PreparedStatement对象，该对象将生成具有给定类型和并发性的ResultSet对象。
    PreparedStatement
    prepareStatement​(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability)
    Creates a PreparedStatement object that will generate ResultSet objects with the given type, concurrency, and holdability.创建PreparedStatement对象，该对象将生成具有给定类型、并发性和可保持性的ResultSet对象。
    PreparedStatement
    prepareStatement​(String sql, String[] columnNames)
    Creates a default PreparedStatement object capable of returning the auto-generated keys designated by the given array.创建一个默认PreparedStatement对象，该对象能够返回由给定数组指定的自动生成的键。
    void
    releaseSavepoint​(Savepoint savepoint)
    Removes the specified Savepoint and subsequent Savepoint objects from the current transaction.从当前事务中删除指定的Savepoint和后续Savepoint对象。
    void
    rollback()
    Undoes all changes made in the current transaction and releases any database locks currently held by this Connection object.撤消在当前事务中所做的所有更改，并释放此Connection对象当前持有的所有数据库锁。
    void
    rollback​(Savepoint savepoint)
    Undoes all changes made after the given Savepoint object was set.撤消设置给定Savepoint对象后所做的所有更改。
    void
    setAutoCommit​(boolean autoCommit)
    Sets this connection's auto-commit mode to the given state.将此连接的自动提交模式设置为给定状态。
    void
    setCatalog​(String catalog)
    Sets the given catalog name in order to select a subspace of this Connection object's database in which to work.设置给定的目录名称，以便选择要在其中工作的此连接Connection数据库的子空间。
    void
    setClientInfo​(String name, String value)
    Sets the value of the client info property specified by name to the value specified by value.将“名称”指定的“客户端信息”属性的值设置为“值”指定的值。
    void
    setClientInfo​(Properties properties)
    Sets the value of the connection's client info properties.设置连接的客户端信息属性的值。
    void
    setHoldability​(int holdability)
    Changes the default holdability of ResultSet objects created using this Connection object to the given holdability.将使用此Connection对象创建的ResultSet对象的默认保持性更改为给定的保持性。
    void
    setNetworkTimeout​(Executor executor, int milliseconds)
    Sets the maximum period a Connection or objects created from the Connection will wait for the database to reply to any one request.设置Connection或通过Connection创建的对象等待数据库答复任何一个请求的最长时间。
    void
    setReadOnly​(boolean readOnly)
    Puts this connection in read-only mode as a hint to the driver to enable database optimizations.将此连接置于只读模式，以提示驱动程序启用数据库优化。
    Savepoint
    setSavepoint()
    Creates an unnamed savepoint in the current transaction and returns the new Savepoint object that represents it.在当前事务中创建未命名的保存点，并返回表示该保存点的新Savepoint对象。
    Savepoint
    setSavepoint​(String name)
    Creates a savepoint with the given name in the current transaction and returns the new Savepoint object that represents it.在当前事务中创建具有给定名称的保存点，并返回表示该保存点的新Savepoint对象。
    void
    setSchema​(String schema)
    Sets the given schema name to access.设置要访问的给定架构名称。
    default void
    setShardingKey​(ShardingKey shardingKey)
    Specifies a shardingKey to use with this Connection指定用于此连接的分片键
    default void
    setShardingKey​(ShardingKey shardingKey, ShardingKey superShardingKey)
    Specifies a shardingKey and superShardingKey to use with this Connection指定用于此连接的shardingKey和superShardingKey
    default boolean
    setShardingKeyIfValid​(ShardingKey shardingKey, int timeout)
    Sets and validates the sharding key for this connection.设置并验证此连接的分片键。
    default boolean
    setShardingKeyIfValid​(ShardingKey shardingKey, ShardingKey superShardingKey, int timeout)
    Sets and validates the sharding keys for this connection.设置并验证此连接的分片键。
    void
    setTransactionIsolation​(int level)
    Attempts to change the transaction isolation level for this Connection object to the one given.尝试将此Connection对象的事务隔离级别更改为给定的级别。
    void
    setTypeMap​(Map<String,​Class<?>> map)
    Installs the given TypeMap object as the type map for this Connection object.将给定的TypeMap对象安装为此Connection对象的类型映射。

    Methods declared in interface java.sql.Wrapper在java.sql.Wrapper接口中声明的方法

    isWrapperFor, unwrap

  • Field Details字段详情

    • TRANSACTION_NONE

      static final int TRANSACTION_NONE
      A constant indicating that transactions are not supported.指示不支持事务的常量。
      See Also:参阅：
      Constant Field Values常量字段值

    • TRANSACTION_READ_UNCOMMITTED

      static final int TRANSACTION_READ_UNCOMMITTED
      A constant indicating that dirty reads, non-repeatable reads and phantom reads can occur. 一个常量，指示可能发生脏读、不可重复读和幻象读。This level allows a row changed by one transaction to be read by another transaction before any changes in that row have been committed (a "dirty read"). 此级别允许一个事务更改的行在提交该行的任何更改之前被另一个事务读取（“脏读”）。 If any of the changes are rolled back, the second transaction will have retrieved an invalid row.如果回滚了任何更改，则第二个事务将检索到无效行。
      See Also:参阅：
      Constant Field Values常量字段值

    • TRANSACTION_READ_COMMITTED

      static final int TRANSACTION_READ_COMMITTED
      A constant indicating that dirty reads are prevented; non-repeatable reads and phantom reads can occur. 指示防止脏读的常数；可能发生不可重复读取和幻象读取。This level only prohibits a transaction from reading a row with uncommitted changes in it.此级别仅禁止事务读取包含未提交更改的行。
      See Also:参阅：
      Constant Field Values常量字段值

    • TRANSACTION_REPEATABLE_READ

      static final int TRANSACTION_REPEATABLE_READ
      A constant indicating that dirty reads and non-repeatable reads are prevented; phantom reads can occur. 指示防止脏读和不可重复读的常数；可能发生幻象读取。 This level prohibits a transaction from reading a row with uncommitted changes in it, and it also prohibits the situation where one transaction reads a row, a second transaction alters the row, and the first transaction rereads the row, getting different values the second time (a "non-repeatable read").此级别禁止事务读取包含未提交更改的行，还禁止一个事务读取行，第二个事务更改行，第一个事务重新读取行，第二次获得不同的值（“不可重复读取”）。
      See Also:参阅：
      Constant Field Values常量字段值

    • TRANSACTION_SERIALIZABLE

      static final int TRANSACTION_SERIALIZABLE
      A constant indicating that dirty reads, non-repeatable reads and phantom reads are prevented. 一个常量，指示阻止脏读、不可重复读和幻象读。This level includes the prohibitions in TRANSACTION_REPEATABLE_READ and further prohibits the situation where one transaction reads all rows that satisfy a WHERE condition, a second transaction inserts a row that satisfies that WHERE condition, and the first transaction rereads for the same condition, retrieving the additional "phantom" row in the second read.此级别包括TRANSACTION_REPEATABLE_READ中的禁止，并进一步禁止一个事务读取满足where条件的所有行，第二个事务插入满足where条件的行，并且第一个事务针对相同条件重新读取，检索第二次读取中的附加“幻影”行。
      See Also:参阅：
      Constant Field Values常量字段值

  • Method Details方法详情

    • createStatement

      Statement createStatement() throws SQLException
      Creates a Statement object for sending SQL statements to the database. 创建用于向数据库发送SQL语句的Statement对象。SQL statements without parameters are normally executed using Statement objects. 没有参数的SQL语句通常使用Statement对象执行。If the same SQL statement is executed many times, it may be more efficient to use a PreparedStatement object. 如果同一SQL语句执行多次，则使用PreparedStatement对象可能会更有效。

      Result sets created using the returned Statement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY. 默认情况下，使用返回Statement对象创建的结果集的类型为TYPE_FORWARD_ONLY类型，并发级别为CONCUR_READ_ONLY。The holdability of the created result sets can be determined by calling getHoldability().创建的结果集的可保持性可以通过调用getHoldability()来确定。

      Returns:返回：
      a new default Statement object一个新的默认Statement对象
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection如果发生数据库访问错误或在关闭的连接上调用此方法

    • prepareStatement

      PreparedStatement prepareStatement​(String sql) throws SQLException
      Creates a PreparedStatement object for sending parameterized SQL statements to the database. 创建PreparedStatement对象，用于将参数化SQL语句发送到数据库。

      A SQL statement with or without IN parameters can be pre-compiled and stored in a PreparedStatement object. 带或不带IN参数的SQL语句可以预编译并存储在PreparedStatement对象中。This object can then be used to efficiently execute this statement multiple times. 然后可以使用该对象多次有效地执行该语句。

      Note:注意: This method is optimized for handling parametric SQL statements that benefit from precompilation. 此方法针对处理从预编译中获益的参数化SQL语句进行了优化。If the driver supports precompilation, the method prepareStatement will send the statement to the database for precompilation. 如果驱动程序支持预编译，则方法prepareStatement会将语句发送到数据库进行预编译。Some drivers may not support precompilation. 某些驱动程序可能不支持预编译。In this case, the statement may not be sent to the database until the PreparedStatement object is executed. 在这种情况下，在执行PreparedStatement对象之前，语句可能不会发送到数据库。This has no direct effect on users; however, it does affect which methods throw certain SQLException objects. 这对用户没有直接影响；但是，它确实会影响哪些方法抛出某些SQLException对象。

      Result sets created using the returned PreparedStatement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY. The holdability of the created result sets can be determined by calling getHoldability().

      Parameters:参数：
      sql - an SQL statement that may contain one or more '?' IN parameter placeholders参数占位符中可能包含一个或多个“?”的SQL语句
      Returns:返回：
      a new default PreparedStatement object containing the pre-compiled SQL statement包含预编译SQL语句的新默认PreparedStatement对象
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection如果发生数据库访问错误或在关闭的连接上调用此方法

    • prepareCall

      CallableStatement prepareCall​(String sql) throws SQLException
      Creates a CallableStatement object for calling database stored procedures. The CallableStatement object provides methods for setting up its IN and OUT parameters, and methods for executing the call to a stored procedure.

      Note: This method is optimized for handling stored procedure call statements. Some drivers may send the call statement to the database when the method prepareCall is done; others may wait until the CallableStatement object is executed. This has no direct effect on users; however, it does affect which method throws certain SQLExceptions.

      Result sets created using the returned CallableStatement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY. The holdability of the created result sets can be determined by calling getHoldability().

      Parameters:参数：
      sql - an SQL statement that may contain one or more '?' parameter placeholders. Typically this statement is specified using JDBC call escape syntax.
      Returns:返回：
      a new default CallableStatement object containing the pre-compiled SQL statement
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection

    • nativeSQL

      String nativeSQL​(String sql) throws SQLException
      Converts the given SQL statement into the system's native SQL grammar. A driver may convert the JDBC SQL grammar into its system's native SQL grammar prior to sending it. This method returns the native form of the statement that the driver would have sent.
      Parameters:参数：
      sql - an SQL statement that may contain one or more '?' parameter placeholders
      Returns:返回：
      the native form of this statement
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection

    • setAutoCommit

      void setAutoCommit​(boolean autoCommit) throws SQLException
      Sets this connection's auto-commit mode to the given state. If a connection is in auto-commit mode, then all its SQL statements will be executed and committed as individual transactions. Otherwise, its SQL statements are grouped into transactions that are terminated by a call to either the method commit or the method rollback. By default, new connections are in auto-commit mode.

      The commit occurs when the statement completes. The time when the statement completes depends on the type of SQL Statement:

      • For DML statements, such as Insert, Update or Delete, and DDL statements, the statement is complete as soon as it has finished executing.
      • For Select statements, the statement is complete when the associated result set is closed.
      • For CallableStatement objects or for statements that return multiple results, the statement is complete when all of the associated result sets have been closed, and all update counts and output parameters have been retrieved.

      NOTE: If this method is called during a transaction and the auto-commit mode is changed, the transaction is committed. If setAutoCommit is called and the auto-commit mode is not changed, the call is a no-op.

      Parameters:参数：
      autoCommit - true to enable auto-commit mode; false to disable it
      Throws:抛出：
      SQLException - if a database access error occurs, setAutoCommit(true) is called while participating in a distributed transaction, or this method is called on a closed connection
      See Also:参阅：
      getAutoCommit()

    • getAutoCommit

      boolean getAutoCommit() throws SQLException
      Retrieves the current auto-commit mode for this Connection object.
      Returns:返回：
      the current state of this Connection object's auto-commit mode
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection
      See Also:参阅：
      setAutoCommit(boolean)

    • commit

      void commit() throws SQLException
      Makes all changes made since the previous commit/rollback permanent and releases any database locks currently held by this Connection object. This method should be used only when auto-commit mode has been disabled.
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called while participating in a distributed transaction, if this method is called on a closed connection or this Connection object is in auto-commit mode
      See Also:参阅：
      setAutoCommit(boolean)

    • rollback

      void rollback() throws SQLException
      Undoes all changes made in the current transaction and releases any database locks currently held by this Connection object. This method should be used only when auto-commit mode has been disabled.
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called while participating in a distributed transaction, this method is called on a closed connection or this Connection object is in auto-commit mode
      See Also:参阅：
      setAutoCommit(boolean)

    • close

      void close() throws SQLException
      Releases this Connection object's database and JDBC resources immediately instead of waiting for them to be automatically released.

      Calling the method close on a Connection object that is already closed is a no-op.

      It is strongly recommended that an application explicitly commits or rolls back an active transaction prior to calling the close method. If the close method is called and there is an active transaction, the results are implementation-defined.

      Specified by:
      close in interface AutoCloseable
      Throws:抛出：
      SQLException - if a database access error occurs

    • isClosed

      boolean isClosed() throws SQLException
      Retrieves whether this Connection object has been closed. A connection is closed if the method close has been called on it or if certain fatal errors have occurred. This method is guaranteed to return true only when it is called after the method Connection.close has been called.

      This method generally cannot be called to determine whether a connection to a database is valid or invalid. A typical client can determine that a connection is invalid by catching any exceptions that might be thrown when an operation is attempted.

      Returns:返回：
      true if this Connection object is closed; false if it is still open
      Throws:抛出：
      SQLException - if a database access error occurs

    • getMetaData

      DatabaseMetaData getMetaData() throws SQLException
      Retrieves a DatabaseMetaData object that contains metadata about the database to which this Connection object represents a connection. The metadata includes information about the database's tables, its supported SQL grammar, its stored procedures, the capabilities of this connection, and so on.
      Returns:返回：
      a DatabaseMetaData object for this Connection object
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection

    • setReadOnly

      void setReadOnly​(boolean readOnly) throws SQLException
      Puts this connection in read-only mode as a hint to the driver to enable database optimizations.

      Note: This method cannot be called during a transaction.

      Parameters:参数：
      readOnly - true enables read-only mode; false disables it
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called on a closed connection or this method is called during a transaction

    • isReadOnly

      boolean isReadOnly() throws SQLException
      Retrieves whether this Connection object is in read-only mode.
      Returns:返回：
      true if this Connection object is read-only; false otherwise
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection

    • setCatalog

      void setCatalog​(String catalog) throws SQLException
      Sets the given catalog name in order to select a subspace of this Connection object's database in which to work.

      If the driver does not support catalogs, it will silently ignore this request.

      Calling setCatalog has no effect on previously created or prepared Statement objects. It is implementation defined whether a DBMS prepare operation takes place immediately when the Connection method prepareStatement or prepareCall is invoked. For maximum portability, setCatalog should be called before a Statement is created or prepared.

      Parameters:参数：
      catalog - the name of a catalog (subspace in this Connection object's database) in which to work
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection
      See Also:参阅：
      getCatalog()

    • getCatalog

      String getCatalog() throws SQLException
      Retrieves this Connection object's current catalog name.
      Returns:返回：
      the current catalog name or null if there is none
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection
      See Also:参阅：
      setCatalog(java.lang.String)

    • setTransactionIsolation

      void setTransactionIsolation​(int level) throws SQLException
      Attempts to change the transaction isolation level for this Connection object to the one given. The constants defined in the interface Connection are the possible transaction isolation levels.

      Note: If this method is called during a transaction, the result is implementation-defined.

      Parameters:参数：
      level - one of the following Connection constants: Connection.TRANSACTION_READ_UNCOMMITTED, Connection.TRANSACTION_READ_COMMITTED, Connection.TRANSACTION_REPEATABLE_READ, or Connection.TRANSACTION_SERIALIZABLE. (Note that Connection.TRANSACTION_NONE cannot be used because it specifies that transactions are not supported.)
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called on a closed connection or the given parameter is not one of the Connection constants
      See Also:参阅：
      DatabaseMetaData.supportsTransactionIsolationLevel(int), getTransactionIsolation()

    • getTransactionIsolation

      int getTransactionIsolation() throws SQLException
      Retrieves this Connection object's current transaction isolation level.
      Returns:返回：
      the current transaction isolation level, which will be one of the following constants: Connection.TRANSACTION_READ_UNCOMMITTED, Connection.TRANSACTION_READ_COMMITTED, Connection.TRANSACTION_REPEATABLE_READ, Connection.TRANSACTION_SERIALIZABLE, or Connection.TRANSACTION_NONE.
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection
      See Also:参阅：
      setTransactionIsolation(int)

    • getWarnings

      SQLWarning getWarnings() throws SQLException
      Retrieves the first warning reported by calls on this Connection object. If there is more than one warning, subsequent warnings will be chained to the first one and can be retrieved by calling the method SQLWarning.getNextWarning on the warning that was retrieved previously.

      This method may not be called on a closed connection; doing so will cause an SQLException to be thrown.

      Note: Subsequent warnings will be chained to this SQLWarning.

      Returns:返回：
      the first SQLWarning object or null if there are none
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection
      See Also:参阅：
      SQLWarning

    • clearWarnings

      void clearWarnings() throws SQLException
      Clears all warnings reported for this Connection object. After a call to this method, the method getWarnings returns null until a new warning is reported for this Connection object.
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection

    • createStatement

      Statement createStatement​(int resultSetType, int resultSetConcurrency) throws SQLException
      Creates a Statement object that will generate ResultSet objects with the given type and concurrency. This method is the same as the createStatement method above, but it allows the default result set type and concurrency to be overridden. The holdability of the created result sets can be determined by calling getHoldability().
      Parameters:参数：
      resultSetType - a result set type; one of ResultSet.TYPE_FORWARD_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE
      resultSetConcurrency - a concurrency type; one of ResultSet.CONCUR_READ_ONLY or ResultSet.CONCUR_UPDATABLE
      Returns:返回：
      a new Statement object that will generate ResultSet objects with the given type and concurrency
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called on a closed connection or the given parameters are not ResultSet constants indicating type and concurrency
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method or this method is not supported for the specified result set type and result set concurrency.
      Since:始于：
      1.2

    • prepareStatement

      PreparedStatement prepareStatement​(String sql, int resultSetType, int resultSetConcurrency) throws SQLException
      Creates a PreparedStatement object that will generate ResultSet objects with the given type and concurrency. This method is the same as the prepareStatement method above, but it allows the default result set type and concurrency to be overridden. The holdability of the created result sets can be determined by calling getHoldability().
      Parameters:参数：
      sql - a String object that is the SQL statement to be sent to the database; may contain one or more '?' IN parameters
      resultSetType - a result set type; one of ResultSet.TYPE_FORWARD_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE
      resultSetConcurrency - a concurrency type; one of ResultSet.CONCUR_READ_ONLY or ResultSet.CONCUR_UPDATABLE
      Returns:返回：
      a new PreparedStatement object containing the pre-compiled SQL statement that will produce ResultSet objects with the given type and concurrency
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called on a closed connection or the given parameters are not ResultSet constants indicating type and concurrency
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method or this method is not supported for the specified result set type and result set concurrency.
      Since:始于：
      1.2

    • prepareCall

      CallableStatement prepareCall​(String sql, int resultSetType, int resultSetConcurrency) throws SQLException
      Creates a CallableStatement object that will generate ResultSet objects with the given type and concurrency. This method is the same as the prepareCall method above, but it allows the default result set type and concurrency to be overridden. The holdability of the created result sets can be determined by calling getHoldability().
      Parameters:参数：
      sql - a String object that is the SQL statement to be sent to the database; may contain on or more '?' parameters
      resultSetType - a result set type; one of ResultSet.TYPE_FORWARD_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE
      resultSetConcurrency - a concurrency type; one of ResultSet.CONCUR_READ_ONLY or ResultSet.CONCUR_UPDATABLE
      Returns:返回：
      a new CallableStatement object containing the pre-compiled SQL statement that will produce ResultSet objects with the given type and concurrency
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called on a closed connection or the given parameters are not ResultSet constants indicating type and concurrency
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method or this method is not supported for the specified result set type and result set concurrency.
      Since:始于：
      1.2

    • getTypeMap

      Map<String,​Class<?>> getTypeMap() throws SQLException
      Retrieves the Map object associated with this Connection object. Unless the application has added an entry, the type map returned will be empty.

      You must invoke setTypeMap after making changes to the Map object returned from getTypeMap as a JDBC driver may create an internal copy of the Map object passed to setTypeMap: 

            Map<String,Class<?>> myMap = con.getTypeMap();
      myMap.put("mySchemaName.ATHLETES", Athletes.class);
      con.setTypeMap(myMap);
      Returns:返回：
      the java.util.Map object associated with this Connection object
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:始于：
      1.2
      See Also:参阅：
      setTypeMap(java.util.Map<java.lang.String, java.lang.Class<?>>)

    • setTypeMap

      void setTypeMap​(Map<String,​Class<?>> map) throws SQLException
      Installs the given TypeMap object as the type map for this Connection object. The type map will be used for the custom mapping of SQL structured types and distinct types.

      You must set the values for the TypeMap prior to callng setMap as a JDBC driver may create an internal copy of the TypeMap: 

            Map myMap<String,Class<?>> = new HashMap<String,Class<?>>();
      myMap.put("mySchemaName.ATHLETES", Athletes.class);
      con.setTypeMap(myMap);
      Parameters:参数：
      map - the java.util.Map object to install as the replacement for this Connection object's default type map
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called on a closed connection or the given parameter is not a java.util.Map object
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:始于：
      1.2
      See Also:参阅：
      getTypeMap()

    • setHoldability

      void setHoldability​(int holdability) throws SQLException
      Changes the default holdability of ResultSet objects created using this Connection object to the given holdability. The default holdability of ResultSet objects can be determined by invoking DatabaseMetaData.getResultSetHoldability().
      Parameters:参数：
      holdability - a ResultSet holdability constant; one of ResultSet.HOLD_CURSORS_OVER_COMMIT or ResultSet.CLOSE_CURSORS_AT_COMMIT
      Throws:抛出：
      SQLException - if a database access occurs, this method is called on a closed connection, or the given parameter is not a ResultSet constant indicating holdability
      SQLFeatureNotSupportedException - if the given holdability is not supported
      Since:始于：
      1.4
      See Also:参阅：
      getHoldability(), DatabaseMetaData.getResultSetHoldability(), ResultSet

    • getHoldability

      int getHoldability() throws SQLException
      Retrieves the current holdability of ResultSet objects created using this Connection object.
      Returns:返回：
      the holdability, one of ResultSet.HOLD_CURSORS_OVER_COMMIT or ResultSet.CLOSE_CURSORS_AT_COMMIT
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection
      Since:始于：
      1.4
      See Also:参阅：
      setHoldability(int), DatabaseMetaData.getResultSetHoldability(), ResultSet

    • setSavepoint

      Savepoint setSavepoint() throws SQLException
      Creates an unnamed savepoint in the current transaction and returns the new Savepoint object that represents it.

      if setSavepoint is invoked outside of an active transaction, a transaction will be started at this newly created savepoint.

      Returns:返回：
      the new Savepoint object
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called while participating in a distributed transaction, this method is called on a closed connection or this Connection object is currently in auto-commit mode
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:始于：
      1.4
      See Also:参阅：
      Savepoint

    • setSavepoint

      Savepoint setSavepoint​(String name) throws SQLException
      Creates a savepoint with the given name in the current transaction and returns the new Savepoint object that represents it.

      if setSavepoint is invoked outside of an active transaction, a transaction will be started at this newly created savepoint.

      Parameters:参数：
      name - a String containing the name of the savepoint
      Returns:返回：
      the new Savepoint object
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called while participating in a distributed transaction, this method is called on a closed connection or this Connection object is currently in auto-commit mode
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:始于：
      1.4
      See Also:参阅：
      Savepoint

    • rollback

      void rollback​(Savepoint savepoint) throws SQLException
      Undoes all changes made after the given Savepoint object was set.

      This method should be used only when auto-commit has been disabled.

      Parameters:参数：
      savepoint - the Savepoint object to roll back to
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called while participating in a distributed transaction, this method is called on a closed connection, the Savepoint object is no longer valid, or this Connection object is currently in auto-commit mode
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:始于：
      1.4
      See Also:参阅：
      Savepoint, rollback()

    • releaseSavepoint

      void releaseSavepoint​(Savepoint savepoint) throws SQLException
      Removes the specified Savepoint and subsequent Savepoint objects from the current transaction. Any reference to the savepoint after it have been removed will cause an SQLException to be thrown.
      Parameters:参数：
      savepoint - the Savepoint object to be removed
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called on a closed connection or the given Savepoint object is not a valid savepoint in the current transaction
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:始于：
      1.4

    • createStatement

      Statement createStatement​(int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException
      Creates a Statement object that will generate ResultSet objects with the given type, concurrency, and holdability. This method is the same as the createStatement method above, but it allows the default result set type, concurrency, and holdability to be overridden.
      Parameters:参数：
      resultSetType - one of the following ResultSet constants: ResultSet.TYPE_FORWARD_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE
      resultSetConcurrency - one of the following ResultSet constants: ResultSet.CONCUR_READ_ONLY or ResultSet.CONCUR_UPDATABLE
      resultSetHoldability - one of the following ResultSet constants: ResultSet.HOLD_CURSORS_OVER_COMMIT or ResultSet.CLOSE_CURSORS_AT_COMMIT
      Returns:返回：
      a new Statement object that will generate ResultSet objects with the given type, concurrency, and holdability
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called on a closed connection or the given parameters are not ResultSet constants indicating type, concurrency, and holdability
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method or this method is not supported for the specified result set type, result set holdability and result set concurrency.
      Since:始于：
      1.4
      See Also:参阅：
      ResultSet

    • prepareStatement

      PreparedStatement prepareStatement​(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException
      Creates a PreparedStatement object that will generate ResultSet objects with the given type, concurrency, and holdability.

      This method is the same as the prepareStatement method above, but it allows the default result set type, concurrency, and holdability to be overridden.

      Parameters:参数：
      sql - a String object that is the SQL statement to be sent to the database; may contain one or more '?' IN parameters
      resultSetType - one of the following ResultSet constants: ResultSet.TYPE_FORWARD_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE
      resultSetConcurrency - one of the following ResultSet constants: ResultSet.CONCUR_READ_ONLY or ResultSet.CONCUR_UPDATABLE
      resultSetHoldability - one of the following ResultSet constants: ResultSet.HOLD_CURSORS_OVER_COMMIT or ResultSet.CLOSE_CURSORS_AT_COMMIT
      Returns:返回：
      a new PreparedStatement object, containing the pre-compiled SQL statement, that will generate ResultSet objects with the given type, concurrency, and holdability
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called on a closed connection or the given parameters are not ResultSet constants indicating type, concurrency, and holdability
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method or this method is not supported for the specified result set type, result set holdability and result set concurrency.
      Since:始于：
      1.4
      See Also:参阅：
      ResultSet

    • prepareCall

      CallableStatement prepareCall​(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException
      Creates a CallableStatement object that will generate ResultSet objects with the given type and concurrency. This method is the same as the prepareCall method above, but it allows the default result set type, result set concurrency type and holdability to be overridden.
      Parameters:参数：
      sql - a String object that is the SQL statement to be sent to the database; may contain on or more '?' parameters
      resultSetType - one of the following ResultSet constants: ResultSet.TYPE_FORWARD_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE
      resultSetConcurrency - one of the following ResultSet constants: ResultSet.CONCUR_READ_ONLY or ResultSet.CONCUR_UPDATABLE
      resultSetHoldability - one of the following ResultSet constants: ResultSet.HOLD_CURSORS_OVER_COMMIT or ResultSet.CLOSE_CURSORS_AT_COMMIT
      Returns:返回：
      a new CallableStatement object, containing the pre-compiled SQL statement, that will generate ResultSet objects with the given type, concurrency, and holdability
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called on a closed connection or the given parameters are not ResultSet constants indicating type, concurrency, and holdability
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method or this method is not supported for the specified result set type, result set holdability and result set concurrency.
      Since:始于：
      1.4
      See Also:参阅：
      ResultSet

    • prepareStatement

      PreparedStatement prepareStatement​(String sql, int autoGeneratedKeys) throws SQLException
      Creates a default PreparedStatement object that has the capability to retrieve auto-generated keys. The given constant tells the driver whether it should make auto-generated keys available for retrieval. This parameter is ignored if the SQL statement is not an INSERT statement, or an SQL statement able to return auto-generated keys (the list of such statements is vendor-specific).

      Note: This method is optimized for handling parametric SQL statements that benefit from precompilation. If the driver supports precompilation, the method prepareStatement will send the statement to the database for precompilation. Some drivers may not support precompilation. In this case, the statement may not be sent to the database until the PreparedStatement object is executed. This has no direct effect on users; however, it does affect which methods throw certain SQLExceptions.

      Result sets created using the returned PreparedStatement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY. The holdability of the created result sets can be determined by calling getHoldability().

      Parameters:参数：
      sql - an SQL statement that may contain one or more '?' IN parameter placeholders
      autoGeneratedKeys - a flag indicating whether auto-generated keys should be returned; one of Statement.RETURN_GENERATED_KEYS or Statement.NO_GENERATED_KEYS
      Returns:返回：
      a new PreparedStatement object, containing the pre-compiled SQL statement, that will have the capability of returning auto-generated keys
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called on a closed connection or the given parameter is not a Statement constant indicating whether auto-generated keys should be returned
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method with a constant of Statement.RETURN_GENERATED_KEYS
      Since:始于：
      1.4

    • prepareStatement

      PreparedStatement prepareStatement​(String sql, int[] columnIndexes) throws SQLException
      Creates a default PreparedStatement object capable of returning the auto-generated keys designated by the given array. This array contains the indexes of the columns in the target table that contain the auto-generated keys that should be made available. The driver will ignore the array if the SQL statement is not an INSERT statement, or an SQL statement able to return auto-generated keys (the list of such statements is vendor-specific).

      An SQL statement with or without IN parameters can be pre-compiled and stored in a PreparedStatement object. This object can then be used to efficiently execute this statement multiple times.

      Note: This method is optimized for handling parametric SQL statements that benefit from precompilation. If the driver supports precompilation, the method prepareStatement will send the statement to the database for precompilation. Some drivers may not support precompilation. In this case, the statement may not be sent to the database until the PreparedStatement object is executed. This has no direct effect on users; however, it does affect which methods throw certain SQLExceptions.

      Result sets created using the returned PreparedStatement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY. The holdability of the created result sets can be determined by calling getHoldability().

      Parameters:参数：
      sql - an SQL statement that may contain one or more '?' IN parameter placeholders
      columnIndexes - an array of column indexes indicating the columns that should be returned from the inserted row or rows
      Returns:返回：
      a new PreparedStatement object, containing the pre-compiled statement, that is capable of returning the auto-generated keys designated by the given array of column indexes
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:始于：
      1.4

    • prepareStatement

      PreparedStatement prepareStatement​(String sql, String[] columnNames) throws SQLException
      Creates a default PreparedStatement object capable of returning the auto-generated keys designated by the given array. This array contains the names of the columns in the target table that contain the auto-generated keys that should be returned. The driver will ignore the array if the SQL statement is not an INSERT statement, or an SQL statement able to return auto-generated keys (the list of such statements is vendor-specific).

      An SQL statement with or without IN parameters can be pre-compiled and stored in a PreparedStatement object. This object can then be used to efficiently execute this statement multiple times.

      Note: This method is optimized for handling parametric SQL statements that benefit from precompilation. If the driver supports precompilation, the method prepareStatement will send the statement to the database for precompilation. Some drivers may not support precompilation. In this case, the statement may not be sent to the database until the PreparedStatement object is executed. This has no direct effect on users; however, it does affect which methods throw certain SQLExceptions.

      Result sets created using the returned PreparedStatement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY. The holdability of the created result sets can be determined by calling getHoldability().

      Parameters:参数：
      sql - an SQL statement that may contain one or more '?' IN parameter placeholders
      columnNames - an array of column names indicating the columns that should be returned from the inserted row or rows
      Returns:返回：
      a new PreparedStatement object, containing the pre-compiled statement, that is capable of returning the auto-generated keys designated by the given array of column names
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:始于：
      1.4

    • createClob

      Clob createClob() throws SQLException
      Constructs an object that implements the Clob interface. The object returned initially contains no data. The setAsciiStream, setCharacterStream and setString methods of the Clob interface may be used to add data to the Clob.
      Returns:返回：
      An object that implements the Clob interface
      Throws:抛出：
      SQLException - if an object that implements the Clob interface can not be constructed, this method is called on a closed connection or a database access error occurs.
      SQLFeatureNotSupportedException - if the JDBC driver does not support this data type
      Since:始于：
      1.6

    • createBlob

      Blob createBlob() throws SQLException
      Constructs an object that implements the Blob interface. The object returned initially contains no data. The setBinaryStream and setBytes methods of the Blob interface may be used to add data to the Blob.
      Returns:返回：
      An object that implements the Blob interface
      Throws:抛出：
      SQLException - if an object that implements the Blob interface can not be constructed, this method is called on a closed connection or a database access error occurs.
      SQLFeatureNotSupportedException - if the JDBC driver does not support this data type
      Since:始于：
      1.6

    • createNClob

      NClob createNClob() throws SQLException
      Constructs an object that implements the NClob interface. The object returned initially contains no data. The setAsciiStream, setCharacterStream and setString methods of the NClob interface may be used to add data to the NClob.
      Returns:返回：
      An object that implements the NClob interface
      Throws:抛出：
      SQLException - if an object that implements the NClob interface can not be constructed, this method is called on a closed connection or a database access error occurs.
      SQLFeatureNotSupportedException - if the JDBC driver does not support this data type
      Since:始于：
      1.6

    • createSQLXML

      SQLXML createSQLXML() throws SQLException
      Constructs an object that implements the SQLXML interface. The object returned initially contains no data. The createXmlStreamWriter object and setString method of the SQLXML interface may be used to add data to the SQLXML object.
      Returns:返回：
      An object that implements the SQLXML interface
      Throws:抛出：
      SQLException - if an object that implements the SQLXML interface can not be constructed, this method is called on a closed connection or a database access error occurs.
      SQLFeatureNotSupportedException - if the JDBC driver does not support this data type
      Since:始于：
      1.6

    • isValid

      boolean isValid​(int timeout) throws SQLException
      Returns true if the connection has not been closed and is still valid. The driver shall submit a query on the connection or use some other mechanism that positively verifies the connection is still valid when this method is called.

      The query submitted by the driver to validate the connection shall be executed in the context of the current transaction.

      Parameters:参数：
      timeout - - The time in seconds to wait for the database operation used to validate the connection to complete. If the timeout period expires before the operation completes, this method returns false. A value of 0 indicates a timeout is not applied to the database operation.
      Returns:返回：
      true if the connection is valid, false otherwise
      Throws:抛出：
      SQLException - if the value supplied for timeout is less than 0
      Since:始于：
      1.6
      See Also:参阅：
      DatabaseMetaData.getClientInfoProperties()

    • setClientInfo

      void setClientInfo​(String name, String value) throws SQLClientInfoException
      Sets the value of the client info property specified by name to the value specified by value.

      Applications may use the DatabaseMetaData.getClientInfoProperties method to determine the client info properties supported by the driver and the maximum length that may be specified for each property.

      The driver stores the value specified in a suitable location in the database. For example in a special register, session parameter, or system table column. For efficiency the driver may defer setting the value in the database until the next time a statement is executed or prepared. Other than storing the client information in the appropriate place in the database, these methods shall not alter the behavior of the connection in anyway. The values supplied to these methods are used for accounting, diagnostics and debugging purposes only.

      The driver shall generate a warning if the client info name specified is not recognized by the driver.

      If the value specified to this method is greater than the maximum length for the property the driver may either truncate the value and generate a warning or generate a SQLClientInfoException. If the driver generates a SQLClientInfoException, the value specified was not set on the connection.

      The following are standard client info properties. Drivers are not required to support these properties however if the driver supports a client info property that can be described by one of the standard properties, the standard property name should be used.

      • ApplicationName - The name of the application currently utilizing the connection
      • ClientUser - The name of the user that the application using the connection is performing work for. This may not be the same as the user name that was used in establishing the connection.
      • ClientHostname - The hostname of the computer the application using the connection is running on.
      Parameters:参数：
      name - The name of the client info property to set
      value - The value to set the client info property to. If the value is null, the current value of the specified property is cleared.
      Throws:抛出：
      SQLClientInfoException - if the database server returns an error while setting the client info value on the database server or this method is called on a closed connection
      Since:始于：
      1.6

    • setClientInfo

      void setClientInfo​(Properties properties) throws SQLClientInfoException
      Sets the value of the connection's client info properties. The Properties object contains the names and values of the client info properties to be set. The set of client info properties contained in the properties list replaces the current set of client info properties on the connection. If a property that is currently set on the connection is not present in the properties list, that property is cleared. Specifying an empty properties list will clear all of the properties on the connection. See setClientInfo (String, String) for more information.

      If an error occurs in setting any of the client info properties, a SQLClientInfoException is thrown. The SQLClientInfoException contains information indicating which client info properties were not set. The state of the client information is unknown because some databases do not allow multiple client info properties to be set atomically. For those databases, one or more properties may have been set before the error occurred.

      Parameters:参数：
      properties - the list of client info properties to set
      Throws:抛出：
      SQLClientInfoException - if the database server returns an error while setting the clientInfo values on the database server or this method is called on a closed connection
      Since:始于：
      1.6
      See Also:参阅：
      setClientInfo(String, String)

    • getClientInfo

      String getClientInfo​(String name) throws SQLException
      Returns the value of the client info property specified by name. This method may return null if the specified client info property has not been set and does not have a default value. This method will also return null if the specified client info property name is not supported by the driver.

      Applications may use the DatabaseMetaData.getClientInfoProperties method to determine the client info properties supported by the driver.

      Parameters:参数：
      name - The name of the client info property to retrieve
      Returns:返回：
      The value of the client info property specified
      Throws:抛出：
      SQLException - if the database server returns an error when fetching the client info value from the database or this method is called on a closed connection
      Since:始于：
      1.6
      See Also:参阅：
      DatabaseMetaData.getClientInfoProperties()

    • getClientInfo

      Properties getClientInfo() throws SQLException
      Returns a list containing the name and current value of each client info property supported by the driver. The value of a client info property may be null if the property has not been set and does not have a default value.
      Returns:返回：
      A Properties object that contains the name and current value of each of the client info properties supported by the driver.
      Throws:抛出：
      SQLException - if the database server returns an error when fetching the client info values from the database or this method is called on a closed connection
      Since:始于：
      1.6

    • createArrayOf

      Array createArrayOf​(String typeName, Object[] elements) throws SQLException
      Factory method for creating Array objects.

      Note:When createArrayOf is used to create an array object that maps to a primitive data type, then it is implementation-defined whether the Array object is an array of that primitive data type or an array of Object.

      Note:The JDBC driver is responsible for mapping the elements Object array to the default JDBC SQL type defined in java.sql.Types for the given class of Object. The default mapping is specified in Appendix B of the JDBC specification. If the resulting JDBC type is not the appropriate type for the given typeName then it is implementation defined whether an SQLException is thrown or the driver supports the resulting conversion.

      Parameters:参数：
      typeName - the SQL name of the type the elements of the array map to. The typeName is a database-specific name which may be the name of a built-in type, a user-defined type or a standard SQL type supported by this database. This is the value returned by Array.getBaseTypeName
      elements - the elements that populate the returned object
      Returns:返回：
      an Array object whose elements map to the specified SQL type
      Throws:抛出：
      SQLException - if a database error occurs, the JDBC type is not appropriate for the typeName and the conversion is not supported, the typeName is null or this method is called on a closed connection
      SQLFeatureNotSupportedException - if the JDBC driver does not support this data type
      Since:始于：
      1.6

    • createStruct

      Struct createStruct​(String typeName, Object[] attributes) throws SQLException
      Factory method for creating Struct objects.
      Parameters:参数：
      typeName - the SQL type name of the SQL structured type that this Struct object maps to. The typeName is the name of a user-defined type that has been defined for this database. It is the value returned by Struct.getSQLTypeName.
      attributes - the attributes that populate the returned object
      Returns:返回：
      a Struct object that maps to the given SQL type and is populated with the given attributes
      Throws:抛出：
      SQLException - if a database error occurs, the typeName is null or this method is called on a closed connection
      SQLFeatureNotSupportedException - if the JDBC driver does not support this data type
      Since:始于：
      1.6

    • setSchema

      void setSchema​(String schema) throws SQLException
      Sets the given schema name to access.

      If the driver does not support schemas, it will silently ignore this request.

      Calling setSchema has no effect on previously created or prepared Statement objects. It is implementation defined whether a DBMS prepare operation takes place immediately when the Connection method prepareStatement or prepareCall is invoked. For maximum portability, setSchema should be called before a Statement is created or prepared.

      Parameters:参数：
      schema - the name of a schema in which to work
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection
      Since:始于：
      1.7
      See Also:参阅：
      getSchema()

    • getSchema

      String getSchema() throws SQLException
      Retrieves this Connection object's current schema name.
      Returns:返回：
      the current schema name or null if there is none
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed connection
      Since:始于：
      1.7
      See Also:参阅：
      setSchema(java.lang.String)

    • abort

      void abort​(Executor executor) throws SQLException
      Terminates an open connection. Calling abort results in:
      • The connection marked as closed
      • Closes any physical connection to the database
      • Releases resources used by the connection
      • Insures that any thread that is currently accessing the connection will either progress to completion or throw an SQLException.

      Calling abort marks the connection closed and releases any resources. Calling abort on a closed connection is a no-op.

      It is possible that the aborting and releasing of the resources that are held by the connection can take an extended period of time. When the abort method returns, the connection will have been marked as closed and the Executor that was passed as a parameter to abort may still be executing tasks to release resources.

      This method checks to see that there is an SQLPermission object before allowing the method to proceed. If a SecurityManager exists and its checkPermission method denies calling abort, this method throws a java.lang.SecurityException.

      Parameters:参数：
      executor - The Executor implementation which will be used by abort.
      Throws:抛出：
      SQLException - if a database access error occurs or the executor is null,
      SecurityException - if a security manager exists and its checkPermission method denies calling abort
      Since:始于：
      1.7
      See Also:参阅：
      SecurityManager.checkPermission(java.security.Permission), Executor

    • setNetworkTimeout

      void setNetworkTimeout​(Executor executor, int milliseconds) throws SQLException
      Sets the maximum period a Connection or objects created from the Connection will wait for the database to reply to any one request. If any request remains unanswered, the waiting method will return with a SQLException, and the Connection or objects created from the Connection will be marked as closed. Any subsequent use of the objects, with the exception of the close, isClosed or Connection.isValid methods, will result in a SQLException.

      Note: This method is intended to address a rare but serious condition where network partitions can cause threads issuing JDBC calls to hang uninterruptedly in socket reads, until the OS TCP-TIMEOUT (typically 10 minutes). This method is related to the abort() method which provides an administrator thread a means to free any such threads in cases where the JDBC connection is accessible to the administrator thread. The setNetworkTimeout method will cover cases where there is no administrator thread, or it has no access to the connection. This method is severe in it's effects, and should be given a high enough value so it is never triggered before any more normal timeouts, such as transaction timeouts.

      JDBC driver implementations may also choose to support the setNetworkTimeout method to impose a limit on database response time, in environments where no network is present.

      Drivers may internally implement some or all of their API calls with multiple internal driver-database transmissions, and it is left to the driver implementation to determine whether the limit will be applied always to the response to the API call, or to any single request made during the API call.

      This method can be invoked more than once, such as to set a limit for an area of JDBC code, and to reset to the default on exit from this area. Invocation of this method has no impact on already outstanding requests.

      The Statement.setQueryTimeout() timeout value is independent of the timeout value specified in setNetworkTimeout. If the query timeout expires before the network timeout then the statement execution will be canceled. If the network is still active the result will be that both the statement and connection are still usable. However if the network timeout expires before the query timeout or if the statement timeout fails due to network problems, the connection will be marked as closed, any resources held by the connection will be released and both the connection and statement will be unusable.

      When the driver determines that the setNetworkTimeout timeout value has expired, the JDBC driver marks the connection closed and releases any resources held by the connection.

      This method checks to see that there is an SQLPermission object before allowing the method to proceed. If a SecurityManager exists and its checkPermission method denies calling setNetworkTimeout, this method throws a java.lang.SecurityException.

      Parameters:参数：
      executor - The Executor implementation which will be used by setNetworkTimeout.
      milliseconds - The time in milliseconds to wait for the database operation to complete. If the JDBC driver does not support milliseconds, the JDBC driver will round the value up to the nearest second. If the timeout period expires before the operation completes, a SQLException will be thrown. A value of 0 indicates that there is not timeout for database operations.
      Throws:抛出：
      SQLException - if a database access error occurs, this method is called on a closed connection, the executor is null, or the value specified for seconds is less than 0.
      SecurityException - if a security manager exists and its checkPermission method denies calling setNetworkTimeout.
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:始于：
      1.7
      See Also:参阅：
      SecurityManager.checkPermission(java.security.Permission), Statement.setQueryTimeout(int), getNetworkTimeout(), abort(java.util.concurrent.Executor), Executor

    • getNetworkTimeout

      int getNetworkTimeout() throws SQLException
      Retrieves the number of milliseconds the driver will wait for a database request to complete. If the limit is exceeded, a SQLException is thrown.
      Returns:返回：
      the current timeout limit in milliseconds; zero means there is no limit
      Throws:抛出：
      SQLException - if a database access error occurs or this method is called on a closed Connection
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:始于：
      1.7
      See Also:参阅：
      setNetworkTimeout(java.util.concurrent.Executor, int)

    • beginRequest

      default void beginRequest() throws SQLException
      Hints to the driver that a request, an independent unit of work, is beginning on this connection. Each request is independent of all other requests with regard to state local to the connection either on the client or the server. Work done between beginRequest, endRequest pairs does not depend on any other work done on the connection either as part of another request or outside of any request. A request may include multiple transactions. There may be dependencies on committed database state as that is not local to the connection.

      Local state is defined as any state associated with a Connection that is local to the current Connection either in the client or the database that is not transparently reproducible.

      Calls to beginRequest and endRequest are not nested. Multiple calls to beginRequest without an intervening call to endRequest is not an error. The first beginRequest call marks the start of the request and subsequent calls are treated as a no-op

      Use of beginRequest and endRequest is optional, vendor specific and should largely be transparent. In particular implementations may detect conditions that indicate dependence on other work such as an open transaction. It is recommended though not required that implementations throw a SQLException if there is an active transaction and beginRequest is called. Using these methods may improve performance or provide other benefits. Consult your vendors documentation for additional information.

      It is recommended to enclose each unit of work in beginRequest, endRequest pairs such that there is no open transaction at the beginning or end of the request and no dependency on local state that crosses request boundaries. Committed database state is not local.

      API Note:
      This method is to be used by Connection pooling managers.

      The pooling manager should call beginRequest on the underlying connection prior to returning a connection to the caller.

      The pooling manager does not need to call beginRequest if:

      • The connection pool caches PooledConnection objects
      • Returns a logical connection handle when getConnection is called by the application
      • The logical Connection is closed by calling Connection.close prior to returning the PooledConnection to the cache.
      Implementation Requirements:
      The default implementation is a no-op.
      Throws:抛出：
      SQLException - if an error occurs
      Since:始于：
      9
      See Also:参阅：
      endRequest(), PooledConnection

    • endRequest

      default void endRequest() throws SQLException
      Hints to the driver that a request, an independent unit of work, has completed. Calls to beginRequest and endRequest are not nested. Multiple calls to endRequest without an intervening call to beginRequest is not an error. The first endRequest call marks the request completed and subsequent calls are treated as a no-op. If endRequest is called without an initial call to beginRequest is a no-op.

      The exact behavior of this method is vendor specific. In particular implementations may detect conditions that indicate dependence on other work such as an open transaction. It is recommended though not required that implementations throw a SQLException if there is an active transaction and endRequest is called.

      API Note:
      This method is to be used by Connection pooling managers.

      The pooling manager should call endRequest on the underlying connection when the applications returns the connection back to the connection pool.

      The pooling manager does not need to call endRequest if:

      • The connection pool caches PooledConnection objects
      • Returns a logical connection handle when getConnection is called by the application
      • The logical Connection is closed by calling Connection.close prior to returning the PooledConnection to the cache.
      Implementation Requirements:
      The default implementation is a no-op.
      Throws:抛出：
      SQLException - if an error occurs
      Since:始于：
      9
      See Also:参阅：
      beginRequest(), PooledConnection

    • setShardingKeyIfValid

      default boolean setShardingKeyIfValid​(ShardingKey shardingKey, ShardingKey superShardingKey, int timeout) throws SQLException
      Sets and validates the sharding keys for this connection. A null value may be specified for the sharding Key. The validity of a null sharding key is vendor-specific. Consult your vendor's documentation for additional information.
      API Note:
      This method validates that the sharding keys are valid for the Connection. The timeout value indicates how long the driver should wait for the Connection to verify that the sharding key is valid before setShardingKeyIfValid returns false.
      Implementation Requirements:
      The default implementation will throw a SQLFeatureNotSupportedException.
      Parameters:参数：
      shardingKey - the sharding key to be validated against this connection. The sharding key may be null
      superShardingKey - the super sharding key to be validated against this connection. The super sharding key may be null.
      timeout - time in seconds before which the validation process is expected to be completed, otherwise the validation process is aborted. A value of 0 indicates the validation process will not time out.
      Returns:返回：
      true if the connection is valid and the sharding keys are valid and set on this connection; false if the sharding keys are not valid or the timeout period expires before the operation completes.
      Throws:抛出：
      SQLException - if an error occurs while performing this validation; a superSharedingKey is specified without a shardingKey; this method is called on a closed connection; or the timeout value is negative.
      SQLFeatureNotSupportedException - if the driver does not support sharding
      Since:始于：
      9
      See Also:参阅：
      ShardingKey, ShardingKeyBuilder

    • setShardingKeyIfValid

      default boolean setShardingKeyIfValid​(ShardingKey shardingKey, int timeout) throws SQLException
      Sets and validates the sharding key for this connection. A null value may be specified for the sharding Key. The validity of a null sharding key is vendor-specific. Consult your vendor's documentation for additional information.
      API Note:
      This method validates that the sharding key is valid for the Connection. The timeout value indicates how long the driver should wait for the Connection to verify that the sharding key is valid before setShardingKeyIfValid returns false.
      Implementation Requirements:
      The default implementation will throw a SQLFeatureNotSupportedException.
      Parameters:参数：
      shardingKey - the sharding key to be validated against this connection. The sharding key may be null
      timeout - time in seconds before which the validation process is expected to be completed,else the validation process is aborted. A value of 0 indicates the validation process will not time out.
      Returns:返回：
      true if the connection is valid and the sharding key is valid to be set on this connection; false if the sharding key is not valid or the timeout period expires before the operation completes.
      Throws:抛出：
      SQLException - if there is an error while performing this validation; this method is called on a closed connection; or the timeout value is negative.
      SQLFeatureNotSupportedException - if the driver does not support sharding
      Since:始于：
      9
      See Also:参阅：
      ShardingKey, ShardingKeyBuilder

    • setShardingKey

      default void setShardingKey​(ShardingKey shardingKey, ShardingKey superShardingKey) throws SQLException
      Specifies a shardingKey and superShardingKey to use with this Connection
      API Note:
      This method sets the specified sharding keys but does not require a round trip to the database to validate that the sharding keys are valid for the Connection.
      Implementation Requirements:
      The default implementation will throw a SQLFeatureNotSupportedException.
      Parameters:参数：
      shardingKey - the sharding key to set on this connection. The sharding key may be null
      superShardingKey - the super sharding key to set on this connection. The super sharding key may be null
      Throws:抛出：
      SQLException - if an error occurs setting the sharding keys; this method is called on a closed connection; or a superSharedingKey is specified without a shardingKey
      SQLFeatureNotSupportedException - if the driver does not support sharding
      Since:始于：
      9
      See Also:参阅：
      ShardingKey, ShardingKeyBuilder

    • setShardingKey

      default void setShardingKey​(ShardingKey shardingKey) throws SQLException
      Specifies a shardingKey to use with this Connection
      API Note:
      This method sets the specified sharding key but does not require a round trip to the database to validate that the sharding key is valid for the Connection.
      Implementation Requirements:
      The default implementation will throw a SQLFeatureNotSupportedException.
      Parameters:参数：
      shardingKey - the sharding key to set on this connection. The sharding key may be null
      Throws:抛出：
      SQLException - if an error occurs setting the sharding key; or this method is called on a closed connection
      SQLFeatureNotSupportedException - if the driver does not support sharding
      Since:始于：
      9
      See Also:参阅：
      ShardingKey, ShardingKeyBuilder