How to cancel downloading in JAVA FTP?

Question

I tried to write a java ftp client to transfer files within our network. One of very usefully function I want to add is to cancel the transfer while files
are downloading or uploading. I can do this on file uploading by closing "ftpclient.put(filename) methods at anytime, but have trouble on closing "ftpClient.get(remoteFilename)". When I tried to close it by using "in.close()", the program stucked. I even tried to kill the thread, but no luck. Can any one give me a hint? Here is the code:
protected void downloadfile ()
byte [] buffer = new byte[BUFFER_SIZE];
try{
FileOutputStream out = new FileOutputStream(Localfilename);
InputStream in = ftpClient.get(remoteFilename); //downloading
// Write to local file
while (true && !cancelORnot)
// write to file
} catch ( Exception ex) { }
finally
try {
if (out ! = null)
out.close(); // this can be closed at any time
if (in != null)
in.close(); // This one stucked if it is in the middle
// of downloading and can not disconnect to the
// ftp server
catch ( IOException ex)
Thanks!

Answer 1

Thank you for replying. I am sorry I forgot including FTP API
information.The FTP API I used is from SUN, JDK, sun.net.ftp.FtpClient. The method is " InputStream in = ftpClient.get(remoteFilename)"and "in.close()" should close downloading. while it is still downloading, in.close() will not work and hang my program on forever. I am just wondering if there is trick to close downloading whenever I want especially in case that network connection is too slow and I want to cancel the job.