Spring Boot Whitelabel Error Page_java

 解决办法：

添加@ResponseBody注解

Spring Boot Whitelabel Error Page_mysql_02

package com.example.demo.controller;

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

@Controller
public class IndexController {
    @RequestMapping(value = "/")
    public @ResponseBody String say() {
        return "Hello Spring Boot";
    }
}

Spring Boot Whitelabel Error Page_mysql_03