How to copy a file on the FTP server to a directory on the same server in Java?

Question

I\'m using Apache Commons FTP to upload a file. Before uploading I want to check if the file already exists on the server and make a backup from it to a backup directory on

Answer 1

If you are using apache commons net FTPClient, there is a direct method to move a file from one location to another location (if the user has proper permissions).

ftpClient.rename(from, to);

or, If you are familiar with ftp commands, you can use something like

ftpClient.sendCommand(FTPCommand.yourCommand, args);
if(FTPReply.isPositiveCompletion(ftpClient.getReplyCode())) {
     //command successful;
} else {
     //check for reply code, and take appropriate action.
}

If you are using any other client, go through the documentation, There wont be much changes between client implementations.

UPDATE:

Above approach moves the file to to directory, i.e, the file won't be there in from directory anymore. Basically ftp protocol meant to be transfer the files from local <-> remote or remote <-> other remote but not to transfer with in the server.

The work around here, would be simpler, get the complete file to a local InputStream and write it back to the server as a new file in the back up directory.

to get the complete file,

ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
ftpClient.retrieveFile(fileName, outputStream);
InputStream is = new ByteArrayInputStream(outputStream.toByteArray());

now, store this stream to backup directory. First we need to change working directory to backup directory.

// assuming backup directory is with in current working directory
ftpClient.setFileType(FTP.BINARY_FILE_TYPE);//binary files
ftpClient.changeWorkingDirectory("backup");
//this overwrites the existing file
ftpClient.storeFile(fileName, is);
//if you don't want to overwrite it use storeUniqueFile

Hope this helps you..

Answer 2

To backup at same Server (move), can you use:

String source="/home/user/some";
String goal  ="/home/user/someOther";
FTPFile[] filesFTP = cliente.listFiles(source);

clientFTP.changeWorkingDirectory(goal);  // IMPORTANT change to final directory

for (FTPFile f : archivosFTP) 
   {
    if(f.isFile())
       {
        cliente.rename(source+"/"+f.getName(), f.getName());
       }
   }

Answer 3

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.

---

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

f.sendCommand("CPFR sourcepath");
f.sendCommand("CPTO targetpath");

---

The second possibility is that your server allows you to execute arbitrary shell commands. This is even less common. If your server supports this you can use SITE EXEC command:

SITE EXEC cp -p sourcepath targetpath

---

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 though) is shown in FTP copy a file to another place in same FTP.

---

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. This is that the answer by @RP- shows.

---

See also FTP copy a file to another place in same FTP.

Answer 4

Try this way,

I am using apache's library .

ftpClient.rename(from, to) will make it easier, i have mentioned in the code below where to add ftpClient.rename(from,to).

public void goforIt(){


        FTPClient con = null;

        try
        {
            con = new FTPClient();
            con.connect("www.ujudgeit.net");

            if (con.login("ujud3", "Stevejobs27!!!!"))
            {
                con.enterLocalPassiveMode(); // important!
                con.setFileType(FTP.BINARY_FILE_TYPE);
                String data = "/sdcard/prerakm4a.m4a";
                ByteArrayInputStream(data.getBytes());
                FileInputStream in = new FileInputStream(new File(data));
                boolean result = con.storeFile("/Ads/prerakm4a.m4a", in);
                in.close();
                if (result) 
                       {
                            Log.v("upload result", "succeeded");

//$$$$$$$$$$$$$$$$$$$$$$$$$$$$$Add the backup Here$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$//

                   // Now here you can store the file into a backup location

                  // Use ftpClient.rename(from, to) to place it in backup

//$$$$$$$$$$$$$$$$$$$$$$$$$$$$$Add the backup Here$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$//

                       }
                con.logout();
                con.disconnect();
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }   

    }