<!--jackson依赖 用来转化json-->
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.9.8</version>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <version>2.3.0.RELEASE</version>
</dependency>

package com.wyh.entity;
/**
 * @program: SpringBoot-Ajax-JSON
 * @description: User实体类
 * @author: 魏一鹤
 * @createDate: 2022-02-07 21:45
 **/
public class User {
private String name;
private int age;
public User() {
    }
    @Override
public String toString() {
return "User{" +
"name='" + name + '\'' +
", age=" + age +
", sex='" + sex + '\'' +
'}';
    }
public User(String name, int age, String sex) {
this.name = name;
this.age = age;
this.sex = sex;
    }
public String getName() {
return name;
    }
public void setName(String name) {
this.name = name;
    }
public int getAge() {
return age;
    }
public void setAge(int age) {
this.age = age;
    }
public String getSex() {
return sex;
    }
public void setSex(String sex) {
this.sex = sex;
    }
private String sex;
}

package com.wyh.controller;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.wyh.entity.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
/**
 * @program: SpringBoot-Ajax-JSON
 * @description: 用户中心控制器 返回接收JSON格式的数据
 * @author: 魏一鹤
 * @createDate: 2022-02-07 21:44
 **/
@Controller
public class UserController {
//现在两大转换json第三方工具主流就是jackson和fastjson(阿里巴巴)
    //如果出现乱码,我们需要设置他的编码格式为utf-8,以及它返回的类型,通过@RequesMapping的produces属性来实现
    //produces:指定响应体返回类型和编码
    @RequestMapping(value = "/json1",produces ="application/json;charset=utf-8")
//正常返回的话会走视图解析器,但是json需要返回的是字符串,使用@ResponseBody就能完美解决
    @ResponseBody //响应 返回json格式的数据 将服务器端返回的对象转换为json对象响应回去
    //@RequestBody //接收 接收json格式的数据 将客户端返回的对象转换为json进行接收
    public String  json1() throws JsonProcessingException {
//需要一个jackson的对象映射器 其实就是一个类 ObjectMapper 使用它可以直接将对象转换为json字符串
        ObjectMapper objectMapper = new ObjectMapper();
//创建一个对象
        User user=new User("魏一鹤",1,"男");
//输出Java对象
        System.out.println("Java对象"+user);
//将Java对象转换为JSON字符串 使用writeValueAsString方法把实体放进去即可转化json字符串 需要抛出异常
        String JSONUser = objectMapper.writeValueAsString(user);
//输出JSON字符串
        System.out.println("JSON字符串"+JSONUser);
//由于使用了@ResponseBody注解 这里会将JSONUser以JSON字符串的格式直接返回 十分方便
        return JSONUser;
    }
}
@RequestMapping(value = "/json2")
@ResponseBody
public String json2() throws JsonProcessingException {
    List<User> list=new ArrayList<>();
    User user1=new User("魏一鹤",1,"男");
    User user2=new User("杨玉婷",2,"女");
    list.add(user1);
    list.add(user2);
    ObjectMapper objectMapper = new ObjectMapper();
    String strJSON = objectMapper.writeValueAsString(list);
return  strJSON;
}