Java code for FTP client

I have wrote a simple code to download a file from a FTP server using the following connection string:

  URL url = new URL("ftp://test:pass@182.71.224.200/sample.txt;type=i");
    URLConnection urlc = url.openConnection();

But while I tried to read the content from the above connection and write on my local drive I got only 61KB. When I opened thesample.txt it has the following content:

06-16-2011  02:47PM           1228317425 sample.txt

But the original size of the sample.txt in FTP is 1.14GB.

urlc.getContentLength() returned -1 for me.

here is my entire code

public void download( String ftpServer, String user, String password,
             String fileName, File destination ) throws MalformedURLException,
             IOException
       {
          if (ftpServer != null && fileName != null && destination != null)
          {
             StringBuffer sb = new StringBuffer( "ftp://" );
             // check for authentication else assume its anonymous access.
             if (user != null && password != null)
             {
                sb.append( user );
                sb.append( ':' );
                sb.append( password );
                sb.append( '@' );
             }
             sb.append( ftpServer );
             sb.append( '/' );
             sb.append( fileName );
             /*
              * type ==> a=ASCII mode, i=image (binary) mode, d= file directory
 开发者_StackOverflow中文版             * listing
              */
             sb.append( ";type=i" );
             BufferedInputStream bis = null;
             BufferedOutputStream bos = null;
             System.out.println(sb);
             try
             {
                URL url = new URL( sb.toString() );
                URLConnection urlc = url.openConnection();
                System.out.println(urlc.getContentType());
                System.out.println(urlc.toString());
                System.out.println(urlc.getContentLength());
                bis = new BufferedInputStream( urlc.getInputStream() );
                bos = new BufferedOutputStream( new FileOutputStream("D://FTP/"+
                      destination.getName() ) );

                int i;
                while ((i = bis.read()) != -1)
                {
                   bos.write( i );
                }
             }
             finally
             {
                if (bis != null)
                   try
                   {
                      bis.close();
                   }
                   catch (IOException ioe)
                   {
                      ioe.printStackTrace();
                   }
                if (bos != null)
                   try
                   {
                      bos.close();
                   }
                   catch (IOException ioe)
                   {
                      ioe.printStackTrace();
                   }
             }
          }
          else
          {
             System.out.println( "Input not available" );
          }
       }

You'll need to open the connection and start streaming the result e.g.

URL url = new URL("ftp://test:pass@182.71.224.200/sample.txt;type=i");
URLConnection urlc = url.openConnection();
InputStream is = urlc.getInputStream(); // To download
etc. etc.

Have you done that? The basic JDK support is limited to streaming the data. You might want to look at a Java FTP client which allows you to interact more richly with the FTP Protocol. I don't have much experience in this area but Apache Commons Net is one such example. With this you would read files as org.apache.commons.net.ftp.FtpFile Objects, which has a getter for the file size.

BTW: -1 for the getContentLength() call is just the default if it can't find a header named "content-length". So I think in your case, because this is FTP the method is not relevant. This adds further weight to try and use a dedicated FTP Library.

No need to reinvent the wheel. I'd recommend using FTP4J which I have used in several projects for file upload/download. http://www.sauronsoftware.it/projects/ftp4j/. I assume the library should be able to take care of the issues for you.

You might want to use an existing library rather than rolling your own, try Apache Commons Net.