1. 点击右上角sign in登录按钮，登录到nexus中
   

2. 登录后，会出现设置按钮，如图
   

3. 点击设置按钮，点击左侧的system，点击API，即可打开restFul接口界面
   

4. 点击打开 Components 组，找到 /v1/components 接口，打开
   

5. 点击 “Try it out”，然后在 repository *required 的输入框中，输入仓库名称，仓库名称，来源于browse列表
   点击 Execute执行，即可看到相应的下载连接
   
   
   

6. 将上面的回参，下载到本地，点击图中的 download，即可下载回参 json 文件

7. 将回参拉到底部，查看continuationToken 的值是否为 null，如下如
   

如果不为null，则表示还有下页，如果为null，则表示当前拉取的数据为全部
9. 如果数据有下页。则拿到continuationToken的值，填写到 请求的continuationToken中，继续执行，然后下载json文件，直到返回的continuationToken的值为null为止

10. 编写java程序，下载json里面的所有jar以及pom到本地
    a. 核心依赖

    <dependencies>
        <dependency>
            <groupId>org.jsoup</groupId>
            <artifactId>jsoup</artifactId>
            <version>1.15.3</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.14.0</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/commons-io/commons-io -->
        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.11.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.12.0</version>
        </dependency>
    </dependencies>

b. 核心代码

package com.mose;

import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.commons.io.FileUtils;
import org.apache.commons.lang3.StringUtils;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class DownloadJar {

    private static final String initPath = "D:\\nexusd\\";
    //    private static final String filePath = "D:\\project-owner\\tools\\nexus-util\\src\\main\\resources\\product.json";

    // 此处若有多个json文件，依次执行即可
    private static final String filePath = "D:\\nexusd\\4.json";
//    private static final String filePath = "/close/tmp/product.json";

    public HashMap<String, Object> readJson() throws IOException {

        ObjectMapper objectMapper = new ObjectMapper();

        FileReader fileReader = new FileReader(filePath);
        BufferedReader bufferedReader = new BufferedReader(fileReader);
        StringBuffer sb = new StringBuffer();
        String s = "";
        while (StringUtils.isNotEmpty(s = bufferedReader.readLine())) {
            sb.append(s.trim());
        }
        return objectMapper.readValue(sb.toString(), HashMap.class);
    }

    public void download() throws IOException {
        HashMap<String, Object> stringStringHashMap = readJson();

        List<Map> list = (List) stringStringHashMap.get("items");

        for (Map map : list) {
            List<Map> assets = (List<Map>) map.get("assets");
            for (Map dMap : assets) {
                String url = dMap.get("downloadUrl") + "";
                String path = dMap.get("path") + "";
                genFile(url, initPath + path);
            }
        }

    }


    private void genFile(final String urlStr, final String path) {
        System.out.println(path);
        try {
            URL url = new URL(urlStr);
            String tempFileName = path;
            // 先创建文件夹
            File t = new File(path);
            t.getParentFile().mkdirs();
            File temp = new File(tempFileName);
            FileUtils.copyURLToFile(url, temp);
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }


    public static void main(String args[]) throws IOException {
        new DownloadJar().download();
    }
}

10. 运行java代码，即可下载所有jar包到本地
    

11. 迁移
    下载迁移工具
    https://agent-install.oss-cn-hangzhou.aliyuncs.com/migrate-local-repo-tool.jar?file=migrate-local-repo-tool.jar

    执行迁移命令

    java -jar migrate-local-repo-tool.jar -cd "D:/nexusd/" -t https://packages.aliyun.com/maven/repository/111 -u '********' -p '***'