1.maven配置

<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->

<dependency>

<groupId>com.alibaba</groupId>

<artifactId>fastjson</artifactId>

<version>1.2.41</version>

</dependency>

<!-- https://mvnrepository.com/artifact/com.google.code.gson/gson -->

<dependency>

<groupId>com.google.code.gson</groupId>

<artifactId>gson</artifactId>

<version>2.8.2</version>

</dependency>

2.demo代码 

/** *  */package jsontest;import com.alibaba.fastjson.JSON;import com.google.gson.Gson;/** * @author jhuang.sjtu * @function null都会过滤掉 * @date 2017年12月10日 * @version */public class TestJson {    /**     * @param args     */    public static void main(String[] args) {        //对象转化为json        User use = new User("admin", null, 20);        String ss = new Gson().toJson(use);        System.out.println(ss);                //json转化为对象        User use222 = new Gson().fromJson(ss, User.class);        System.out.println("use222"+use222.toString());                System.out.println("以上为方法1，以下为方法2===================");                // 用户组对象转JSON串          String jsonString = JSON.toJSONString(use);          System.out.println("jsonString:" + jsonString);          // JSON串转用户组对象          User group2 = JSON.parseObject(jsonString, User.class);          System.out.println("group2:" + group2);              }}