JAVA FILE.renameTo跨文件系统移动文件失败

Posted 2020-12-31 deodara

遇到了FILE.renameTo跨文件系统移动文件失败的问题，应使用FILES.move()接口或在同一文件系统移动文件。

FILE.renameTo接口说明：

public boolean renameTo(File dest)

Renames the file denoted by this abstract pathname.

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.

Note that the Files class defines the move method to move or rename a file in a platform independent manner.

Parameters:

dest - The new abstract pathname for the named file

Returns:

true if and only if the renaming succeeded; false otherwise

Throws:

SecurityException - If a security manager exists and its SecurityManager.checkWrite(java.lang.String) method denies write access to either the old or new pathnames

NullPointerException - If parameter dest is null

Files.move接口说明：

public static Path move(Path source,
        Path target,
        CopyOption... options)
                 throws IOException

Move or rename a file to a target file.

By default, this method attempts to move the file to the target file, failing if the target file exists except if the source and target are the same file, in which case this method has no effect. If the file is a symbolic link then the symbolic link itself, not the target of the link, is moved. This method may be invoked to move an empty directory. In some implementations a directory has entries for special files or links that are created when the directory is created. In such implementations a directory is considered empty when only the special entries exist. When invoked to move a directory that is not empty then the directory is moved if it does not require moving the entries in the directory. For example, renaming a directory on the same FileStore will usually not require moving the entries in the directory. When moving a directory requires that its entries be moved then this method fails (by throwing an IOException). To move a file tree may involve copying rather than moving directories and this can be done using the copy method in conjunction with the Files.walkFileTree utility method.

The options parameter may include any of the following:

Option	Description
REPLACE_EXISTING	If the target file exists, then the target file is replaced if it is not a non-empty directory. If the target file exists and is a symbolic link, then the symbolic link itself, not the target of the link, is replaced.
ATOMIC_MOVE	The move is performed as an atomic file system operation and all other options are ignored. If the target file exists then it is implementation specific if the existing file is replaced or this method fails by throwing an IOException. If the move cannot be performed as an atomic file system operation then AtomicMoveNotSupportedException is thrown. This can arise, for example, when the target location is on a different FileStore and would require that the file be copied, or target location is associated with a different provider to this object.

An implementation of this interface may support additional implementation specific options.

Where the move requires that the file be copied then the last-modified-time is copied to the new file. An implementation may also attempt to copy other file attributes but is not required to fail if the file attributes cannot be copied. When the move is performed as a non-atomic operation, and a IOException is thrown, then the state of the files is not defined. The original file and the target file may both exist, the target file may be incomplete or some of its file attributes may not been copied from the original file.

Usage Examples: Suppose we want to rename a file to "newname", keeping the file in the same directory:

     Path source = ...
     Files.move(source, source.resolveSibling("newname"));
 

Alternatively, suppose we want to move a file to new directory, keeping the same file name, and replacing any existing file of that name in the directory:

     Path source = ...
     Path newdir = ...
     Files.move(source, newdir.resolve(source.getFileName()), REPLACE_EXISTING);
 

Parameters:

source - the path to the file to move

target - the path to the target file (may be associated with a different provider to the source path)

options - options specifying how the move should be done

Returns:

the path to the target file

Throws:

UnsupportedOperationException - if the array contains a copy option that is not supported

FileAlreadyExistsException - if the target file exists but cannot be replaced because the REPLACE_EXISTING option is not specified (optional specific exception)

DirectoryNotEmptyException - the REPLACE_EXISTING option is specified but the file cannot be replaced because it is a non-empty directory (optional specific exception)

AtomicMoveNotSupportedException - if the options array contains the ATOMIC_MOVE option but the file cannot be moved as an atomic file system operation.

IOException - if an I/O error occurs

SecurityException - In the case of the default provider, and a security manager is installed, the checkWrite method is invoked to check write access to both the source and target file.