JSch SFTP upload/download progress

Question

I am new to JSch and Java. I managed to get some code and understand it somehow, but I am stuck on one point. The following code downloads file from SSH/SFTP server, but I am in need of the progress meter that shows percentage of file copied. How can I do it?

import com.jcraft.jsch.ChannelSftp;
import com.jcraft.jsch.JSch;
import com.jcraft.jsch.Session;
import com.jcraft.jsch.SftpProgressMonitor; 
public class SFTPExample {
    public static void main(String args[]) throws Exception {
        String user = "root";
        String password = "password";
        String host = "192.168.0.5";
        int port = 22;
        String knownHostsFilename = "/home/world/.ssh/known_hosts";        
        String sourcePath = "/media/nfs/genotype.txt";
        String destPath = "genotype.txt";        
        JSch jsch = new JSch();
        jsch.setKnownHosts(knownHostsFilename);
        Session session = jsch.getSession(user, host, port);
        session.setPassword(password);
        session.connect(); 
        ChannelSftp sftpChannel = (ChannelSftp) session.openChannel("sftp");
        sftpChannel.connect();
            
        System.out.println("Downloading test file");
        sftpChannel.get(sourcePath, destPath);            
        
        sftpChannel.exit();
        session.disconnect();
    }
}

Answer 1

There are overloads of the get/put methods in the com.jcraft.jsch.ChannelSftp that you use to pass in a callback. Look at the

void get(java.lang.String src, java.lang.String dst, SftpProgressMonitor monitor) 

method and com.jcraft.jsch.SftpProgressMonitor interface. At the bottom of this Example Code (it's kind of messy), you'll find an implementation of SftpProgressMonitor that uses its callback methods count(long) and end() to manipulate a javax.swing.ProgressMonitor.

count(long) gets called periodically when there's some bytes that have been transferred, and end() gets called when the transfer has ended. So a really simple implementation of SftpProgressMonitor could be:

public class SystemOutProgressMonitor implements SftpProgressMonitor
{
    public SystemOutProgressMonitor() {;}

    public void init(int op, java.lang.String src, java.lang.String dest, long max) 
    {
        System.out.println("STARTING: " + op + " " + src + " -> " + dest + " total: " + max);
    }

    public boolean count(long bytes)
    {
        for(int x=0; x < bytes; x++) {
            System.out.print("#");
        }
        return(true);
    }

    public void end()
    {
        System.out.println("\nFINISHED!");
    }
}

I'd then create an instance of that and pass it to get()

sftpChannel.get(sourcePath, destPath, new SystemOutProgressMonitor());