Legacy File I/O Code遗留文件I/O代码

Interoperability With Legacy Code与遗留代码的互操作性

Prior to the Java SE 7 release, the java.io.File class was the mechanism used for file I/O, but it had several drawbacks.在Java SE 7发布之前，java.io.File类是用于文件I/O的机制，但它有几个缺点。

• Many methods didn't throw exceptions when they failed, so it was impossible to obtain a useful error message. 许多方法失败时不会抛出异常，因此不可能获得有用的错误消息。For example, if a file deletion failed, the program would receive a "delete fail" but wouldn't know if it was because the file didn't exist, the user didn't have permissions, or there was some other problem.例如，如果文件删除失败，程序将收到“删除失败”，但不知道这是否是因为文件不存在、用户没有权限或存在其他问题。
• The rename method didn't work consistently across platforms.rename方法在不同平台上的工作不一致。
• There was no real support for symbolic links.对符号链接没有真正的支持。
• More support for metadata was desired, such as file permissions, file owner, and other security attributes.需要更多的元数据支持，例如文件权限、文件所有者和其他安全属性。
• Accessing file metadata was inefficient.访问文件元数据效率低下。
• Many of the File methods didn't scale. 许多File方法无法缩放。Requesting a large directory listing over a server could result in a hang. 通过服务器请求大型目录列表可能会导致挂起。Large directories could also cause memory resource problems, resulting in a denial of service.大目录还可能导致内存资源问题，从而导致拒绝服务。
• It was not possible to write reliable code that could recursively walk a file tree and respond appropriately if there were circular symbolic links.如果存在循环符号链接，则不可能编写能够递归遍历文件树并做出适当响应的可靠代码。

Perhaps you have legacy code that uses java.io.File and would like to take advantage of the java.nio.file.Path functionality with minimal impact to your code.也许您有使用java.io.File的遗留代码，并且希望在对代码影响最小的情况下利用java.nio.file.Path功能。

The java.io.File class provides the toPath method, which converts an old style File instance to a java.nio.file.Path instance, as follows:java.io.File类提供 toPath方法，该方法将旧式文件实例转换为java.nio.File.Path实例，如下所示：

Path input = file.toPath();

You can then take advantage of the rich feature set available to the Path class.然后可以利用Path类可用的丰富功能集。

For example, assume you had some code that deleted a file:例如，假设您有一些删除文件的代码：

file.delete();

You could modify this code to use the Files.delete method, as follows:您可以修改此代码以使用Files.delete方法，如下所示：

Path fp = file.toPath();
Files.delete(fp);

Conversely, the Path.toFile method constructs a java.io.File object for a Path object.相反，Path.toFile方法为Path对象构造java.io.File对象。

Mapping java.io.File Functionality to java.nio.file将java.io.File功能映射到java.nio.File

Because the Java implementation of file I/O has been completely re-architected in the Java SE 7 release, you cannot swap one method for another method. 由于文件I/O的Java实现在JavaSE7版本中已经完全重新设计，因此不能将一种方法替换为另一种方法。If you want to use the rich functionality offered by the java.nio.file package, your easiest solution is to use the File.toPath method as suggested in the previous section. 如果您想使用java.nio.file包提供的丰富功能，最简单的解决方案是使用上一节中建议的File.toPath方法。However, if you do not want to use that approach or it is not sufficient for your needs, you must rewrite your file I/O code.但是，如果您不想使用这种方法，或者它不足以满足您的需要，则必须重写文件I/O代码。

There is no one-to-one correspondence between the two APIs, but the following table gives you a general idea of what functionality in the java.io.File API maps to in the java.nio.file API and tells you where you can obtain more information.这两个API之间没有一对一的对应关系，但下表让您大致了解java.io.File API中的哪些功能映射到java.nio.File API中，并告诉您可以从哪里获得更多信息。