使用fastjson

package cn.alan;

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

/**
 * fastjson的使用
 */
public class Main {

    public static void main(String[] args) {
        /**
         * 1、将JSON串转为Java对象
         */
        String jsonStr="{'userName':'root','password':'123456'}";
        User javaObject=JSON.parseObject(jsonStr, User.class);
        //root
        System.out.println(javaObject.getUserName());
        //123456
        System.out.println(javaObject.getPassword());

        /**
         * 2、Java对象转为JSON字符串
         */
        User user =new User("user","user123");
        String userJson=JSON.toJSONString(user);
        //{"password":"user123","userName":"user"}
        System.out.println(userJson);

        /**
         * 3、JSON字符串转为JSONArray对象，再从JSONArray中取出JSONObject
         */
        String jsonStr3 = "[{\"password\":\"123\",\"userName\":\"张三\"},{\"password\":\"321\", \"userName\":\"李四\"}]";
        JSONArray jsonArray=JSON.parseArray(jsonStr3);
        for (int i = 0; i < jsonArray.size(); i++) {
            JSONObject object=jsonArray.getJSONObject(i);
            //
            String userName=object.getString("userName");
            String password=object.getString("password");
            //张三---123
            //李四---321
            System.out.println(userName+"---"+password);
        }

        /**
         * 4、JSON字符串转为JSONObject，再将JSONObject转为Java对象
         */
        String json4="{'userName':'json4','password':'123'}";
        JSONObject jsonObject4=JSONObject.parseObject(json4);
        User user4= JSONObject.toJavaObject(jsonObject4, User.class);
        //json4---123
        System.out.println(user4.getUserName()+"---"+user4.getPassword());
    }
}

package cn.alan;

/**
 * 测试使用的JavaBean
 * @version 1.0
 * @date 2020/9/4 0:46
 */
public class User {
    private String userName;
    private String password;

    public User() {
    }

    public User(String userName, String password) {
        this.userName = userName;
        this.password = password;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "userName='" + userName + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}