准备工作

1-本地安装Git
2-搭建Gitlab私服
3-创建项目并上传源代码

获取所有项目API

http://your-gitlab-server//api/v4/projects
--每页显示150个项目
http://your-gitlab-server//api/v4/projects?per_page=150

返回json格式的数据，注意默认显示每页20行数据，可以增加参数?per_page=150获取更多的项目
如果有做token安全限制需要增加相关的token参数
获取项目列表后存储为本地JSON，利用java代码生成下载的命令，调用Process 执行下载命令

java代码下载

import java.io.File;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.nio.charset.Charset;
import java.util.Iterator;

import org.springframework.util.StreamUtils;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

public class TestGitlabData {
    
    public static String readJsonFile(String fileName) {
        String jsonStr = "";
        try {
            File jsonFile = new File(fileName);
            FileReader fileReader = new FileReader(jsonFile);
            Reader reader = new InputStreamReader(new FileInputStream(jsonFile),"utf-8");
            int ch = 0;
            StringBuffer sb = new StringBuffer();
            while ((ch = reader.read()) != -1) {
                sb.append((char) ch);
            }
            fileReader.close();
            reader.close();
            jsonStr = sb.toString();
            return jsonStr;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }

    
    public static void main(String[] args) {
    
        String fileName="E:\\gitlab_projects.json";
        String jsonStr=readJsonFile(fileName);
        
        JSONArray projects=JSON.parseArray(jsonStr);
        
        //指定需要下载的分支
        String branchName="devp";
        
        //指定下载后输出的地址
        String srcDir="E:\\prj\\src";
        File execDir = new File(srcDir);
        for (Iterator iterator = projects.iterator(); iterator.hasNext();) {
            JSONObject prj = (JSONObject) iterator.next();
            //项目地址
            String httpUrlToRepo=prj.getString("http_url_to_repo");
            //项目路径
            String pathWithNamespace=prj.getString("path_with_namespace");
            gitClone(branchName,httpUrlToRepo,pathWithNamespace,execDir);
        }
    }

    static void gitClone(String branchName, String httpUrlToRepo,String pathWithNamespace, File execDir) {
        String command = String.format("git clone -b %s %s %s", branchName, httpUrlToRepo, pathWithNamespace);
        try {
            System.out.println("===========start==================");
            System.out.println("start exec command : " + command);
            //执行命令行
            Process exec = Runtime.getRuntime().exec(command, null, execDir);
            exec.waitFor();
            String successResult = StreamUtils.copyToString(exec.getInputStream(), Charset.forName("UTF-8"));
            String errorResult = StreamUtils.copyToString(exec.getErrorStream(),Charset.forName("UTF-8"));
            System.out.println("successResult: " + successResult);
            System.out.println("errorResult: " + errorResult);
            System.out.println("============end================");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

• 可优化，考虑直接利用httpclient工具类直接访问GitLab API获取项目列表