> For the complete documentation index, see [llms.txt](https://documentation.alluxio.io/os-cn/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://documentation.alluxio.io/os-cn/api/clients-hadoop.md).

# 兼容Hadoop的Java

Alluxio通过提供文件系统接口提供对文件的访问方式。Alluxio中的文件提供一次性写的语义：文件在全部写完之后不可修改，并且在全部 写完之前不可以读。Alluxio提供两种不同的文件系统API，Alluxio文件系统API以及兼容Hadoop的API。Alluxio API提供额外的功能性，而用户可以直接使用兼容Hadoop的API获取Hadoop原生API的功能，不用修改已有代码。

Alluxio有[原生文件系统Java客户端](/os-cn/api/fs-api.md)的包装类，可以提供兼容Hadoop的`FileSystem`接口。使用这个客户端时， Hadoop文件操作会被转换为文件系统操作。最新的关于`文件系统`接口的文档可以在[这里](http://hadoop.apache.org/docs/current/api/org/apache/hadoop/fs/FileSystem.html)找到。

兼容Hadoop的接口是为了方便而提供的，这样可以使用户重新利用之前为Hadoop写的代码。


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