JSON入门学习

package com.my.test;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import com.my.entity.Student;
import com.my.entity.Teacher;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.junit.jupiter.api.Test;

/**
 * @author : lijie
 * @version V1.0
 * @Description:
 * @date Date : 2021年07月15日 21:05
 */

public class JSONDemo {

  /**
   * 单个实例：bean<==>json
   */
  @Test
  public void test1() {
    System.out.println("------The Result of test1------");
    // bean==>json
    Student s1 = new Student(1, "zhangsan", 18);
    String s = JSON.toJSONString(s1);
    System.out.println(s);
    // json ==> bean
    String json = "{\"age\":18,\"id\":1,\"name\":\"zhangsan\"}";
    // 1.直接利用JSONObject来获取相应属性值
    System.out.println("--------------1--------------");
    JSONObject jsonObject = JSON.parseObject(json);
    String name = jsonObject.getString("name");
    System.out.println(name);
    int age = jsonObject.getIntValue("age");
    System.out.println(age);
    // 2.将串转成相应java对象，然后再获取属性
    System.out.println("--------------2--------------");
    Student student = JSON.parseObject(json, Student.class);
    System.out.println(student);

  }

  /**
   * 多个实例：bean<==>json
   */
  @Test
  public void test2() {
    System.out.println("------The Result of test2------");
    // bean==>json
    List<Student> students = Arrays
        .asList(new Student(1, "zhangsan", 18), new Student(2, "lisi", 19));
    String studentsJSON = JSON.toJSONString(students);
    System.out.println(studentsJSON);
    // json ==> bean
    String json = "[{\"age\":18,\"id\":1,\"name\":\"zhangsan\"},{\"age\":19,\"id\":2,\"name\":\"lisi\"}]";
    // 利用JSONArray获取相应属性值
    JSONArray jsonArray = JSON.parseArray(json);
    System.out.println(jsonArray.get(0));
    System.out.println(jsonArray.get(1));
    // 直接获取相应的bean对象集合
    List<Student> studentList = JSON.parseArray(json, Student.class);
    System.out.println(studentList);
  }

  @Test
  public void test3() {
    System.out.println("------The Result of test3------");

    List<Student> students = Arrays
        .asList(new Student(1, "zhangsan", 18), new Student(2, "lisi", 19));

    List<Student> students1 = Arrays
        .asList(new Student(3, "wangwu", 20), new Student(4, "qianliu", 21));

    List<List<Student>> lists = new ArrayList<>();
    lists.add(students);
    lists.add(students1);
    String jsonString = JSON.toJSONString(lists);
    System.out.println(jsonString);
    System.out.println("------------------------------------");
    String json = "[[{\"age\":18,\"id\":1,\"name\":\"zhangsan\"},{\"age\":19,\"id\":2,\"name\":\"lisi\"}],[{\"age\":20,\"id\":3,\"name\":\"wangwu\"},{\"age\":21,\"id\":4,\"name\":\"qianliu\"}]]";
    JSONArray jsonArray = JSON.parseArray(json);
    System.out.println(jsonArray.get(0));
    System.out.println(jsonArray.get(1));
    String s = JSON.toJSONString(jsonArray.get(1));
    JSONArray jsonArray1 = JSON.parseArray(s);
    System.out.println(jsonArray1.get(0));
    System.out.println(jsonArray1.get(1));

    List<Student> students2 = JSON.parseArray(s, Student.class);
    System.out.println(students2);

  }
}

===========================================结果如下==================================================
------The Result of test1------
{"age":18,"id":1,"name":"zhangsan"}
--------------1--------------
zhangsan
18
--------------2--------------
Student(id=1, name=zhangsan, age=18)



------The Result of test2------
[{"age":18,"id":1,"name":"zhangsan"},{"age":19,"id":2,"name":"lisi"}]
{"name":"zhangsan","id":1,"age":18}
{"name":"lisi","id":2,"age":19}
[Student(id=1, name=zhangsan, age=18), Student(id=2, name=lisi, age=19)]



------The Result of test3------
[[{"age":18,"id":1,"name":"zhangsan"},{"age":19,"id":2,"name":"lisi"}],[{"age":20,"id":3,"name":"wangwu"},{"age":21,"id":4,"name":"qianliu"}]]
------------------------------------
[{"name":"zhangsan","id":1,"age":18},{"name":"lisi","id":2,"age":19}]
[{"name":"wangwu","id":3,"age":20},{"name":"qianliu","id":4,"age":21}]
{"name":"wangwu","id":3,"age":20}
{"name":"qianliu","id":4,"age":21}
[Student(id=3, name=wangwu, age=20), Student(id=4, name=qianliu, age=21)]

 

 

 

 

 

 

 

 

 

 

 

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