Duplicate remote file over FTP protocol in Java (c

问题:

I m using Apache FTPClient. I was a do a copy of file in a folder just like cp -p, but from Java. How can I do that using 'sendCommand' method or will it be possible any other way? The rename method moves the file but does not keep a backup copy.

回答1:

There's no standard way to duplicate a remote file over FTP protocol. Some FTP servers support proprietary or non-standard extensions for this though.

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So if your are lucky that your server is ProFTPD with mod_copy module, you can use FTP.sendCommand to issue these two commands:

CPFR sourcepath
CPTO targetpath

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The second possibility is that your server allows you to execute arbitrary shell commands. This is not common either. If your server supports this you can use SITE EXEC command:

SITE EXEC cp -p sourcepath targetpath

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Another workaround is to open a second connection to the FTP server and make the server upload the file to itself by piping a passive mode data connection to an active mode data connection. Implementation of this solution in PHP is shown in FTP copy a file to another place in same FTP.

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If neither of this works, all you can do is to download the file to a local temporary location and re-upload it back to the target location.

See also:

• FTP copy a file to another place in same FTP.
• How to copy a file on the ftp server to a directory on the same server in java?