Spring Boot:使用控制器调用JSP时出现404错误

问题描述：

使用Spring Tool Suite运行项目时出现以下错误，

I'm getting the following error when running my project using Spring Tool Suite,

但是如果我的问题是我已经将适当的依赖项添加到了pom.XML文件中.那么可能是什么问题?

But in case my problem is I have already added the appropriate dependencies to pom.XML file. So what could be the problem?

我的pom.XML文件依赖性如下，

        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <version>2.1.3.RELEASE</version>
        </dependency>

我的控制器ApplicationController.java如下，

package com.example.demo.controller;

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

@Controller
public class ApplicationController {

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

我的灵魂在src/main/webapp/WEB-INF/view/welcomepage.jsp中，您可以在下面查看树状视图，

My vives are in src/main/webapp/WEB-INF/view/welcomepage.jsp you can look the tree view below,

我也已经更改了application.properties文件.但是，我还是不明白哪里出了问题.

And I have already changed the application.properties file as well. But still, I can't understand what is wrong.

我的application.properties文件如下，

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

我只是在我的welcomepage.jsp中打个招呼，

I just print hello in My welcomepage.jsp,

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
hello
</body>
</html>

答

看起来您与正在运行的应用程序非常接近.代码中的主要问题是Jasper依赖项在<scope>provided</scope>中. 而且看起来您正在通过main方法从Eclipse IDE运行代码.

Looks like you was very close to the working application. The main issue in your code is in <scope>provided</scope> for your Jasper dependency. And also looks like you are running your code from eclipse IDE through the main method.

长话短说:

如果要通过MyApplication.java中的main方法运行应用程序，则只需删除Jasper的作用域provided.

If you would like to run your application through the main method in MyApplication.java then just remove scope provided for the Jasper.

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

或者您也可以像现在从控制台一样在那种状态下完全运行您的应用程序:

Or you can run your application exactly in that state like you have right now from the console:

mvn clean spring-boot:run

但是我建议删除此作用域，以便您可以从IDE和控制台运行代码.除此之外，spring-boot-starter-tomcat依赖项似乎是多余的(必须在spring-boot-starter-web中可用).简而言之，请尝试使用以下pom文件:

But I suggest to remove this scope so you could be able to run your code from IDE and from console. In addition to that looks like spring-boot-starter-tomcat dependency is redundant (it must be available within spring-boot-starter-web). In a nutshell please try to use following pom file:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
        <relativePath/>
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
        </dependency>
    </dependencies>
</project>

希望我的回答对您有所帮助.

Hope my answer will help you.

Spring Boot:使用控制器调用JSP时出现404错误

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