How to clone git using ssh in Java ?

This article explains about how to clone the git with ssh keys in java. This might be really helpful if you working on any git related works like enhancing on git services / add (or) modifying some files for some of your custom needs in git.

Dependency

<dependency>
	<groupId>org.eclipse.jgit</groupId>
	<artifactId>org.eclipse.jgit.ssh.jsch</artifactId>
	<version>5.11.1.202105131744-r</version>
</dependency>

Latest can be downloaded from here

Generate SSH Keys (Private & Public Keys):

ssh-keygen -t rsa -m PEM

This will ask for the key name and password. Please do remember the password as the same should be given in the java code later.

Add your ssh key

ssh-add git-ssh  // to add the key
ssh-add -l // to check the existing keys

Possible Errors & Solutions

Error connecting to agent: No such file or directory

unable to start ssh-agent service, error :1058:

If you encounter any of the above errors then open powershell in administrator mode and run these commands,

Set-Service ssh-agent -StartupType Manual
Start-Service ssh-agent

Copy public ssh key to your github /bitbucket

This command copies your public ssh key to clipboard.

type git-ssh.pub | clip 

github.com > settings > SSH and GPG keys

Java code to clone git using ssh keys

package com.ngdeveloper.java_git_ssh;

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;

import org.eclipse.jgit.api.Git;
import org.eclipse.jgit.api.TransportConfigCallback;
import org.eclipse.jgit.api.errors.GitAPIException;
import org.eclipse.jgit.api.errors.InvalidRemoteException;
import org.eclipse.jgit.api.errors.TransportException;
import org.eclipse.jgit.transport.JschConfigSessionFactory;
import org.eclipse.jgit.transport.OpenSshConfig;
import org.eclipse.jgit.transport.SshSessionFactory;
import org.eclipse.jgit.transport.SshTransport;
import org.eclipse.jgit.transport.Transport;
import org.eclipse.jgit.util.FS;

import com.jcraft.jsch.JSch;
import com.jcraft.jsch.JSchException;
import com.jcraft.jsch.Session;

public class GitDownload {
  private static final String sshPrivateFilePath = "D:\\github\\ssh-key\\git-ssh"; // replace with your ssh private
  // key path
  private static final String sshPassword = "ngdeveloper"; // replace with your ssh key password
  private static final String sshGitURI = "git@github.com:ngdeveloper-projects/android-toast.git"; // replace with
  // your git
  // project URI

  public static void main(String[] args)
  throws InvalidRemoteException, TransportException, GitAPIException, IOException {
    File workingDir = Files.createTempDirectory("workspace").toFile();

    TransportConfigCallback transportConfigCallback = new SshTransportConfigCallback();

    Git git = Git.cloneRepository().setDirectory(workingDir).setTransportConfigCallback(transportConfigCallback)
      .setURI(sshGitURI).call();
    System.out.println("Project cloned through SSH in: " + workingDir.getPath());
  }

  private static class SshTransportConfigCallback implements TransportConfigCallback {

    private final SshSessionFactory sshSessionFactory = new JschConfigSessionFactory() {
      @Override
      protected void configure(OpenSshConfig.Host hc, Session session) {
        session.setConfig("StrictHostKeyChecking", "no");
      }

      @Override
      protected JSch createDefaultJSch(FS fs) throws JSchException {
        JSch jSch = super.createDefaultJSch(fs);
        jSch.addIdentity(sshPrivateFilePath, sshPassword.getBytes());
        return jSch;
      }
    };

    @Override
    public void configure(Transport transport) {
      SshTransport sshTransport = (SshTransport) transport;
      sshTransport.setSshSessionFactory(sshSessionFactory);
    }

  }

}

Output

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
Project cloned through SSH in: C:\Users\Ngdeveloper\AppData\Local\Temp\workspace1469196261233043335

And in this path: C:\Users\Ngdeveloper\AppData\Local\Temp\workspace1469196261233043335, I can able to see the complete code is cloned/downloaded.

Download