The Java Tutorials have been written for JDK 8.Java教程是为JDK 8编写的。Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.本页中描述的示例和实践没有利用后续版本中引入的改进,并且可能使用不再可用的技术。See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.有关Java SE 9及其后续版本中更新的语言特性的摘要,请参阅Java语言更改。
See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.有关所有JDK版本的新功能、增强功能以及已删除或不推荐的选项的信息,请参阅JDK发行说明。
To look up an object from the naming service, use Context.lookup() and pass it the name of the object that you want to retrieve. Suppose that there is an object in the naming service with the name cn=Rosanna Lee,ou=People. To retrieve the object, you would write
Object obj = ctx.lookup("cn=Rosanna Lee,ou=People");
The type of object that is returned by lookup() depends both on the underlying naming system and on the data associated with the object itself. A naming system can contain many different types of objects, and a lookup of an object in different parts of the system might yield objects of different types. In this example, "cn=Rosanna Lee,ou=People" happens to be bound to a context object (javax.naming.ldap.LdapContext). You can cast the result of lookup() to its target class.
For example, the following code looks up the object "cn=Rosanna Lee,ou=People" and casts it to LdapContext.
import javax.naming.ldap.LdapContext; ... LdapContext ctx = (LdapContext) ctx.lookup("cn=Rosanna Lee,ou=People");
The complete example is in the file Lookup.java
.
There are two new static methods available in Java SE 6 to lookup a name:
These methods provide a shortcut way of looking up a name without instantiating an InitialContext.