SpringBoot+jsp项目启动出现404[通俗易懂]

spring.mvc.view.prefix=/WEB-INF/jsp/
spring.mvc.view.suffix=.jsp

package com.example.demo.controller;

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

@Controller
public class IndexController {

    @RequestMapping("/")
    public String index() {
        return "index";
    }
}

Whitelabel Error Page
This application has no explicit mapping for /error, so you are seeing this as a fallback.

Thu Feb 28 22:59:29 CST 2019
There was an unexpected error (type=Not Found, status=404).
No message available

<dependency>
    <groupId>org.apache.tomcat.embed</groupId>
    <artifactId>tomcat-embed-jasper</artifactId>
</dependency>
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>jstl</artifactId>
</dependency>

<build>
    <resources>
        <resource>
            <directory>src/main/webapp</directory>
            <!--这里必须是META-INF/resources-->
            <targetPath>META-INF/resources</targetPath>
            <includes>
                <include>**/**</include>
            </includes>
            <filtering>false</filtering>
        </resource>
    </resources>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <version>1.4.2.RELEASE</version>
        </plugin>
    </plugins>
</build>