1.String 转 Json

@Test
public void test(){
    String str = "{\"age\":\"24\",\"name\":\"hekliu\"}";  
    JSONObject jsonObject = JSONObject.parseObject(str);
    System.out.println("json对象是：" + jsonObject);
    Object object = jsonObject.get("name");
    System.out.println("name值是：" + object);
}

运行结果：

json对象是：{"name":"hekliu","age":"24"} 

name值是：hekliu

2.Json 转 String

@Test
public void test(){
    String str = "{\"age\":\"24\",\"name\":\"hekliu\"}";
    JSONObject jsonObject = JSONObject.parseObject(str);
    //json对象转字符串
    String jsonString = jsonObject.toJSONString();
    System.out.println("json字符串是：" + jsonString);
}

运行结果：
        json字符串是：{"name":"hekliu","age":"24"}

3.String 转 Map

@Test
public void test(){
    String str = "{\"age\":\"24\",\"name\":\"hekliu\"}";
    JSONObject jsonObject = JSONObject.parseObject(str);
    //json对象转Map
    Map<String, Object> map = (Map<String, Object>)jsonObject;
    System.out.println("map对象是：" + map);
    Object object = map.get("age");
    System.out.println("age的值是" + object);
}

运行结果：
        map对象是：{"name":"hekliu","age":"24"}
        age的值是24

4.Map 转 String

@Test
public void test(){
    Map<String,Object> map = new HashMap<>();
    map.put("age", 24);
    map.put("name", "hekliu");
    String jsonString = JSON.toJSONString(map);
    System.out.println("json字符串是：" + jsonString);
}

运行结果：
        json字符串是：{"name":"hekliu","age":24}

5.Map 转 Json

@Test
public void test(){
    Map<String,Object> map = new HashMap<>();
    map.put("age", 24);
    map.put("name", "hekliu");
    JSONObject json = new JSONObject(map);
    System.out.println("Json对象是：" + json);
}

运行结果：
        Json对象是：{"name":"hekliu","age":24}

6.Json 转 Map

     见示例3

7.对象与字符串之间的互转

//将对象转换成为字符串
String str = JSON.toJSONString(infoDo);
//字符串转换成为对象
InfoDo infoDo = JSON.parseObject(strInfoDo, InfoDo.class);

8.对象集合与字符串之间的互转

//将对象集合转换成为字符串
String users = JSON.toJSONString(users);
//将字符串转换成为对象集合
List<User> userList = JSON.parseArray(userStr, User.class);