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今天遇到一个很狗血的问题，一个功能在开发环境没有问题，但在生产环境出错了。
代码如下：
... File tmpFile = new File(fileTmpPath); File newFileTarget = new File(filePath); tmpFile.renameTo(newFileTarget); // 修改新文件的权限 FileManageHelper.chmod(newFileTarget); ....
最后报错信息提示执行chmod命令失败，但这个代码在开发环境没有问题啊。
仔细查找原因发现jdk的renameTo方法介绍如下：
/**
* Renames the file denoted by this abstract pathname.
*
* <p> Many aspects of the behavior of this method are inherently
* platform-dependent: The rename operation might not be able to move a
* file from one filesystem to another, it might not be atomic, and it
* might not succeed if a file with the destination abstract pathname
* already exists. The return value should always be checked to make sure
* that the rename operation was successful.
*
* <p> Note that the {@link java.nio.file.Files} class defines the {@link
* java.nio.file.Files#move move} method to move or rename a file in a
* platform independent manner.
*
* @param dest The new abstract pathname for the named file
*
* @return <code>true</code> if and only if the renaming succeeded;
* <code>false</code> otherwise
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
* method denies write access to either the old or new pathnames
*
* @throws NullPointerException
* If parameter <code>dest</code> is <code>null</code>
*/
The rename operation might not be able to move a file from one filesystem to another
也就是说如果文件是从一个文件系统将文件move到另一个文件系统有可能失败，正好开发环境上tmpFile与newFileTarget在同一个文件系统中，而在生产环境中由于HA方案的原因这两个文件在不同的文件系统。
教训：一定要检查File的相关操作的返回值，如setLastModified, setReadOnly, setWritable, setReadable, setExecutable, createNewFile, delete, mkdir, mkdirs
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原文地址：http://my.oschina.net/jeremyxu2010/blog/404661
