Whitelabel error page access

function springboot The access interface reports an error when , As shown in the figure above , Back end controller The layer code is as follows ：

package com.hu.sprintboot01.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
@RequestMapping("/hello")
public class HelloController {
    @GetMapping("/hello")
    @ResponseBody
    public String hello(){
        return "hello";
    }
}

visit localhost:8080/hello/hello The address will report an exception , It was later found that the cause of the abnormality was IDEA Problems with directory structure ,Application The startup class is in the wrong position , To put Application Class on the outermost side , That is, it contains all sub packages . And my controller It's in the outermost bag . The page cannot be found .

  After revising controller layer And then access the interface again , Page display normal .