JGit- Create or Open Repository

The JGit framework is rich and diverse, it has two layers, a low-level api and a higher-level set of porcelain commands. This can be a bit intimidating at first as there are lots of classes, some of which are not relevant for most tasks.

package com.javavillage.gitrepo;

import java.io.File;
import java.io.IOException;

import org.dstadler.jgit.helper.CookbookHelper;
import org.eclipse.jgit.api.Git;
import org.eclipse.jgit.api.errors.GitAPIException;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.storage.file.FileRepositoryBuilder;

/**
 * Simple snippet which shows how to open an existing repository
 * 
 * @author Soha
 */
public class GitRepository {

   public static void main(String[] args) throws IOException, GitAPIException {
		// first create a test-repository, the return is including the .get
		// directory here!
		File repoDir = createGitRepo();

		// now open the resulting repository with a FileRepositoryBuilder
		FileRepositoryBuilder builder = new FileRepositoryBuilder();
		Repository repository = builder.setGitDir(repoDir).readEnvironment() // scan
																				// environment
																				// GIT_*
																				// variables
				.findGitDir() // scan up the file system tree
				.build();

		System.out.println("Having repository: " + repository.getDirectory());

		// the Ref holds an ObjectId for any type of object (tree, commit, blob,
		// tree)
		Ref head = repository.getRef("F:/repo");
		System.out.println("Ref of F:/repo: " + head);
	}

	private static File createGitRepo() throws IOException, GitAPIException {
		Repository repository = GitHelper.openRepository();
		System.out.println("Temporary repository at " + repository.getDirectory());

		// create the file
		File myfile = new File(repository.getDirectory().getParent(),
		"testfile");
		myfile.createNewFile();

		// run the add-call
		Git git = new Git(repository);
		git.add().addFilepattern("testfile").call();

		// and then commit the changes
		git.commit().setMessage("Added testfile").call();

		System.out.println("Added file  to repository at " + repository.getDirectory());

		File dir = repository.getDirectory();

		return dir;
	}
}

Helper class which can use across git project

package com.javavillage.gitrepo.helper;
import java.io.File;
import java.io.IOException;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.storage.file.FileRepositoryBuilder;

public class GitHelper {

    public static Repository openRepository() throws IOException {
        FileRepositoryBuilder builder = new FileRepositoryBuilder();
       
        Repository repository = builder.setGitDir(new File("F:/repo"))
                .readEnvironment() // scan environment GIT_* variables
                .findGitDir() // scan up the file system tree
                .build();
        return repository;
    }

    public static Repository createNewRepository() throws IOException {
        // prepare a new folder
        File localPath = File.createTempFile("F:/repo", "");
        localPath.delete();

        // create the directory
        Repository repository = FileRepositoryBuilder.create(new File("F:/repo", ".git"));
        repository.create();

        return repository;
    }
}

If any file is created, if u want to add it index use below snippet for that

            Repository repository = GitHelper.createNewRepository();
            Git git = new Git(repository);
                // create the file
                File myfile = new File(repository.getDirectory().getParent(), "testfile");
                myfile.createNewFile();
        
                // run the add-call
                git.add()
                        .addFilepattern("testfile")
                        .call();
        
                System.out.println("Added file " + myfile + " to repository at " + repository.getDirectory());
          				

Now will try running above code to see jgit basic example, try to install eclipse plugin as per below link

Without having any basic folder in git repository if we run above code will get below error.

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.
Temporary repository at F:\repo
Exception in thread "main" org.eclipse.jgit.errors.NoWorkTreeException: Bare Repository has neither a working tree, nor an index
	at org.eclipse.jgit.lib.Repository.getIndexFile(Repository.java:997)
	at org.eclipse.jgit.dircache.DirCache.lock(DirCache.java:267)
	at org.eclipse.jgit.lib.Repository.lockDirCache(Repository.java:1053)
	at org.eclipse.jgit.api.AddCommand.call(AddCommand.java:142)
	at com.javavillage.gitrepo.GitRepository.createGitRepo(GitRepository.java:53)
	at com.javavillage.gitrepo.GitRepository.main(GitRepository.java:25)

Follow below steps to commit ur code from eclipse. Use share project option

Select repository for to commit the code

After that right click on project goto Team -> commit the code

Once execution done you can see file which got committed to git.