1. 没有@RequestBody

@RequestMapping("/verify")
public Object verify(User user){
}

ajax写法

 $.ajax({
                type:"post",
                url:"${pageContext.request.contextPath}/user/verify.do",
                dataType:"json",
                data : data.field,
                success : function(msg) {
                }
        }）

2.含有@RequestBody

@RequestMapping("/verify")
public void verify(@RequestBody User user){}

 $.ajax({
                type:"post",
                url:"${pageContext.request.contextPath}/user/verifyr.do",
                dataType:"json",
                contentType : "application/json;charset=UTF-8", // 指定这个协议很重要  
                data : JSON.stringify(data.field),
                success : function(msg) {
                }
                })

两者的区别有两个

JSON.stringify()和contentType : "application/json;charset=UTF-8"

具体解释contentType