springMVC的controller接受ajax的post请求

刚刚学习SpringMVC ，ajax发送post请求出现了一些问题，记录一下。

@RequestBody 接收客户端发送的ajax请求中的json字符串,后端自动转换为User对象

前端

var username = $('#username').val();
var password = $('#password').val();
var data = {username : username , password: password};
if(username != "" && password != ""){
    $.ajax({
        type: "post",
        url: "${pageContext.request.contextPath}/user/login",
        dataType: "json",
        contentType: "application/json",//设置类型为json
        data: JSON.stringify(data),//数据要经过这个进行处理转为json字符串
        //JSON.stringify() 方法用于将 JavaScript 值转换为 JSON 字符串
        success: function (msg) {
            //处理
        },
        error:function () {
            alert("错误")
        }
    });
}else {
    alert('请输入账号密码')
}

controller

    @PostMapping(value = "/login")
    @ResponseBody
    public String login(@RequestBody User pass_user,HttpSession session){
        User user = userService.login(pass_user.getUsername(), pass_user.getPassword());

        if (user != null) {
            session.setAttribute("user",user);
            return "1";
        }
        return "0";
    }

也可以用map接收

    @PostMapping(value = "/login")
    @ResponseBody
    public String login(@RequestBody Map<String,Object> pass_user,HttpSession session){
        User user = userService.login(pass_user.get("username").toString(), pass_user.get("password").toString());

        if (user != null) {
            session.setAttribute("user",user);
            return "1";
        }
        return "0";
    }

json字符串和JavaBean对象互相转换的过程中，需要使用jackson的jar包

maven加入的依赖

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.11.0</version>
</dependency>