Java uses jgit to manage git warehouse

Recently designed a new cicd scheme based on gitops. You need to read and write git warehouse through Java. Here is a simple record.

Jgit is a pure java software package that can read and write git warehouse. The basic use is described below.

Introducing jgit

Maven introduction:

        <!-- https://mvnrepository.com/artifact/org.eclipse.jgit/org.eclipse.jgit -->
        <dependency>
            <groupId>org.eclipse.jgit</groupId>
            <artifactId>org.eclipse.jgit</artifactId>
            <version>5.6.0.201912101111-r</version>
        </dependency>

Jgit has a git class that can be used to perform regular git operations

Voucher management

Credentials are managed through the credentialsprovider. The commonly used is usernamepasswordcredentialsprovider

Initialize with the following code:

public static CredentialsProvider createCredential(String userName,String password) {
        return new UsernamePasswordCredentialsProvider(userName,password);
    }

Clone remote warehouse

Git command:

git clone {repoUrl}

Through GIT Clonerepository is a remote warehouse. If credentials are required, you need to specify the credentialsprovider

 public static Git fromCloneRepository(String repoUrl,String cloneDir,CredentialsProvider provider) throws GitAPIException {
        Git git = Git.cloneRepository()
            .setCredentialsProvider(provider)
            .setURI(repoUrl)
            .setDirectory(new File(cloneDir)).call();
        return git;
    }

commit

Git command:

git commit -a -m '{msg}'

Commit is relatively simple. It corresponds to the commit method. Note that you need to add first

    public static void commit(Git git,String message,CredentialsProvider provider) throws GitAPIException {
        git.add().addFilepattern(".").call();
        git.commit()
            .setMessage(message)
            .call();
    }

push

Git command:

git push origin branchName

Push simply calls push, and credentialsprovider needs to be specified

   public static void push(Git git,CredentialsProvider provider) throws GitAPIException,IOException {
        push(git,null,provider);
    }

    public static void push(Git git,String branch,IOException {
        if (branch == null) {
            branch = git.getRepository().getBranch();
        }
        git.push()
            .setCredentialsProvider(provider)
            .setRemote("origin").setRefSpecs(new RefSpec(branch)).call();
    }

Read existing warehouse

What if git has clone and wants to read directly?

 public static Repository getRepositoryFromDir(String dir) throws IOException {
        return new FileRepositoryBuilder()
            .setGitDir(Paths.get(dir,".git").toFile())
            .build();
    }

Read warehouse log

You can read the warehouse log through revwalk.

 public static List<String> getLogs(Repository repository) throws IOException {
        return getLogsSinceCommit(repository,null);
    }

    public static List<String> getLogsSinceCommit(Repository repository,String commit) throws IOException {
        return getLogsSinceCommit(repository,commit);
    }

    public static List<String> getLogsSinceCommit(Repository repository,String commit) throws IOException {
        if (branch == null) {
            branch = repository.getBranch();
        }
        Ref head = repository.findRef("refs/heads/" + branch);
        List<String> commits = new ArrayList<>();
        if (head != null) {
            try (RevWalk revWalk = new RevWalk(repository)) {
                revWalk.markStart(revWalk.parseCommit(head.getObjectId()));
                for (RevCommit revCommit : revWalk) {
                    if (revCommit.getId().getName().equals(commit)) {
                        break;
                    }
                    commits.add(revCommit.getFullMessage());
                    System.out.println("\nCommit-Message: " + revCommit.getFullMessage());
                }
                revWalk.dispose();
            }
        }

        return commits;
    }

test

Let's first clone the warehouse, then modify it, and finally push it

 String yaml = "dependencies:\n" +
            "- name: springboot-rest-demo\n" +
            "  version: 0.0.5\n" +
            "  repository: http://hub.hubHOST.com/chartrepo/ainote\n" +
            "  alias: demo\n" +
            "- name: exposecontroller\n" +
            "  version: 2.3.82\n" +
            "  repository: http://chartmuseum.jenkins-x.io\n" +
            "  alias: cleanup\n";
        CredentialsProvider provider = createCredential("USR_NAME","PASSWORD");

        String cloneDir = "/tmp/test";

        Git git = fromCloneRepository("http://gitlab.GITHOST.cn/datahub/env-test.git",cloneDir,provider);

        // 修改文件

        FileUtils.writeStringToFile(Paths.get(cloneDir,"env","requirements.yaml").toFile(),yaml,"utf-8");
	  
	    // 提交
        commit(git,"deploy(app): deploy  springboot-rest-demo:0.0.5 to env test",provider);
        // push 到远程仓库
        push(git,"master",provider);

        git.clean().call();
        git.close();

        FileUtils.deleteDirectory(new File(cloneDir));

Read logs of existing warehouses:

        Repository repository = getRepositoryFromDir("GIT_DIR");
        List<String> logs = getLogs(repository);
        System.out.println(logs);

        RevCommit head = getLastCommit(repository);
        System.out.println(head.getFullMessage());

Summary

This article describes how to complete conventional git operations through jgit.