使用了jQuery $.Ajax访问springMVC的controller 请求成功 可是回调函数进入了error函数 并且浏览器返回错误信息

Failed to load resource: the server responded with a status of 404 ()

下面放代码

Ajax

function login(that) {
            $.ajax({
                data: {
                    username:$("#username").val(),
                    password:$("#password").val()
                },
                type: "post",
                url: "/checklogin",
                dataType: "json",
                error: function (data) {
                    console.log(data);
                    $(that).removeClass("processing");
                },
                success: function (response) {
                    $(that).removeClass("processing");
                    if (response == "error") {
                        $("#msg").text("用户名或密码错误");
                    } else {
                        window.location.href = "/welcome";
                    }
                }
            });
        }
        
         

Controller

@Controller
public class LoginController {
    @Autowired
    private UserService userService;
    
    @RequestMapping("/checklogin")
    public String checkLogin(@RequestParam("username") String username, @RequestParam("password") String password, HttpSession session){
        System.out.println(username  + "-" + password);
        User user = userService.login(username, password);
        if(user != null){
            return "success";
        }
        else{
            return "error";
        }
    }
}