添加json依赖

 <!--spring-json依赖-->
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.9.0</version>
    </dependency>

注解

• @RequestBody：作用是接收前端ajax传递给后端的json字符串，并将json格式的数据转为java对象

• @ResponseBody：作用是将java对象转为json格式的数据传递给前台ajax

案例

• 编写controller

@Controller
@RequestMapping("/account")
public class AccountController {

    @PostMapping("/findAccount12")
    @ResponseBody
    public JsonStatus findAccount12(@RequestBody Account account) {
        //Map<String ,Object> map = new HashMap<>();
        //map.put("status",200);
        //map.put("msg",account);
        JsonStatus jsonStatus = new JsonStatus();
        try {
            //System.out.println(1/0);
            jsonStatus.setStatus(200);
            jsonStatus.setMsg(account);
        } catch (Exception e) {
            e.printStackTrace();
            jsonStatus.setStatus(500);
            jsonStatus.setMsg("查询错误!!!");
        }
        return jsonStatus;
    }
}

添加实体类：

/*
 * Copyright (c) 2020, 2024,  All rights reserved.
 *
 */
package com.by.pojo;

/**
 * <p>Project: SpringMVC - JsonStatus</p>
 * <p>Powered by scl On 2024-01-09 17:03:33</p>
 * <p>描述：<p>
 *
 * @author 孙臣龙 [1846080280@qq.com]
 * @version 1.0
 * @since 17
 */
public class JsonStatus {
    private Integer status;
    private Object msg;

    public Integer getStatus() {
        return status;
    }

    public void setStatus(Integer status) {
        this.status = status;
    }

    public Object getMsg() {
        return msg;
    }

    public void setMsg(Object msg) {
        this.msg = msg;
    }
}

在index.jsp里面定义ajax请求

• 添加按钮

<input type="button" value="测试ajax请求json和响应json" id="testJson"/>

引入js库文件

<script src="http://libs.baidu.com/jquery/1.9.0/jquery.js"></script>

编写ajax代码

  <script type="text/javascript">
    $(function(){
      $("#testJson").click(function(){
        $.ajax({
          type:"post",
          url:"/account/saveAccount2",
          contentType:"application/json;charset=UTF-8",
          data:'{"id":1,"name":"张二狗","money":999.0}',
          success:function(data){
            if(data.status == 200){
              alert(data.msg.name);
              alert(data.msg.money);
            }
          }
        })
      });
    })
  </script>

结果展示：