HTTP 状态 404 - 在 hello world 期间未找到答案

【问题标题】：HTTP Status 404 – Not Found during hello worldHTTP 状态 404 - 在 hello world 期间未找到
【发布时间】：2019-02-24 21:51:31
【问题描述】：

我是网络应用程序的初学者。我尝试运行第一个应用程序，但出现错误。我从书中复制了所有内容，一切正常，在我的地方不是......通常。我一直在寻找几个小时的解决方案。找不到。我正在使用 10.02 java、Apache Tomcat/9.0.12 和 IntelliJ。

我的文件结构如下所示：

Tomcat的配置是这样的：

HomeController

package com.packt.webstore.controller;

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

@Controller
public class HomeController {
    @RequestMapping("/")
    public String welcome(Model model) {
        model.addAttribute("greeting", "Hello");
        model.addAttribute("tagline", "In the internet");
        return "welcome";
    }
}

welcome.jsp

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.0.0/css/bootstrap.min.css">
    <title>Witaj</title>
</head>
<body>
<section>
    <div class="jumbotron">
        <div class="container">
            <h1> ${greeting} </h1>
            <p> ${tagline} </p>
        </div>
    </div>
</section>
</body>
</html>

DefaultServletservlet.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
 http://www.springframework.org/schema/beans/spring-beans.xsd
 http://www.springframework.org/schema/context
 http://www.springframework.org/schema/context/spring-context-4.0.xsd
 http://www.springframework.org/schema/mvc
 http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd">
    <mvc:annotation-driven/>
    <context:component-scan base-package="com.packt.webstore"/>
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
</beans>

web.xml

<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
 http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <servlet>
        <servlet-name>DefaultServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>DefaultServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

pom.xml

<?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>

    <groupId>com.packt</groupId>
    <artifactId>webstore</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>jstl</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
    </dependencies>

    <build><plugins><plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
            <source>1.8</source>
            <target>1.8</target>
        </configuration>
    </plugin></plugins></build>
</project>

这里是堆栈跟踪：

C:\Users\Admin\Desktop\apache-tomcat-9.0.12\bin\catalina.bat run
[2018-09-20 04:30:29,254] Artifact webstore:war exploded: Waiting for server connection to start artifact deployment...
Using CATALINA_BASE:   "C:\Users\Admin\.IntelliJIdea2018.2\system\tomcat\Unnamed_webstore_2"
Using CATALINA_HOME:   "C:\Users\Admin\Desktop\apache-tomcat-9.0.12"
Using CATALINA_TMPDIR: "C:\Users\Admin\Desktop\apache-tomcat-9.0.12\temp"
Using JRE_HOME:        "C:\Program Files\Java\jdk-10.0.2"
Using CLASSPATH:       "C:\Users\Admin\Desktop\apache-tomcat-9.0.12\bin\bootstrap.jar;C:\Users\Admin\Desktop\apache-tomcat-9.0.12\bin\tomcat-juli.jar"
20-Sep-2018 16:30:31.591 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server version:        Apache Tomcat/9.0.12
20-Sep-2018 16:30:31.596 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server built:          Sep 4 2018 22:13:41 UTC
20-Sep-2018 16:30:31.596 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server number:         9.0.12.0
20-Sep-2018 16:30:31.596 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log OS Name:               Windows 7
20-Sep-2018 16:30:31.597 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log OS Version:            6.1
20-Sep-2018 16:30:31.597 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Architecture:          amd64
20-Sep-2018 16:30:31.597 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Java Home:             C:\Program Files\Java\jdk-10.0.2
20-Sep-2018 16:30:31.597 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log JVM Version:           10.0.2+13
20-Sep-2018 16:30:31.598 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log JVM Vendor:            "Oracle Corporation"
20-Sep-2018 16:30:31.598 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log CATALINA_BASE:         C:\Users\Admin\.IntelliJIdea2018.2\system\tomcat\Unnamed_webstore_2
20-Sep-2018 16:30:31.598 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log CATALINA_HOME:         C:\Users\Admin\Desktop\apache-tomcat-9.0.12
20-Sep-2018 16:30:31.603 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: --add-opens=java.base/java.lang=ALL-UNNAMED
20-Sep-2018 16:30:31.603 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: --add-opens=java.base/java.io=ALL-UNNAMED
20-Sep-2018 16:30:31.604 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: --add-opens=java.rmi/sun.rmi.transport=ALL-UNNAMED
20-Sep-2018 16:30:31.604 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.util.logging.config.file=C:\Users\Admin\.IntelliJIdea2018.2\system\tomcat\Unnamed_webstore_2\conf\logging.properties
20-Sep-2018 16:30:31.604 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager
20-Sep-2018 16:30:31.604 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcom.sun.management.jmxremote=
20-Sep-2018 16:30:31.604 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcom.sun.management.jmxremote.port=1099
20-Sep-2018 16:30:31.605 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcom.sun.management.jmxremote.ssl=false
20-Sep-2018 16:30:31.605 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcom.sun.management.jmxremote.authenticate=false
20-Sep-2018 16:30:31.605 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.rmi.server.hostname=127.0.0.1
20-Sep-2018 16:30:31.605 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djdk.tls.ephemeralDHKeySize=2048
20-Sep-2018 16:30:31.606 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.protocol.handler.pkgs=org.apache.catalina.webresources
20-Sep-2018 16:30:31.606 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dignore.endorsed.dirs=
20-Sep-2018 16:30:31.606 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcatalina.base=C:\Users\Admin\.IntelliJIdea2018.2\system\tomcat\Unnamed_webstore_2
20-Sep-2018 16:30:31.606 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcatalina.home=C:\Users\Admin\Desktop\apache-tomcat-9.0.12
20-Sep-2018 16:30:31.606 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.io.tmpdir=C:\Users\Admin\Desktop\apache-tomcat-9.0.12\temp
20-Sep-2018 16:30:31.607 INFO [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [C:\Program Files\Java\jdk-10.0.2\bin;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;C:\Program Files (x86)\Common Files\Oracle\Java\javapath;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files\Git\cmd;C:\Users\Admin\AppData\Local\GitHubDesktop\bin;.]
20-Sep-2018 16:30:31.690 INFO [main] org.apache.coyote.AbstractProtocol.init Initializing ProtocolHandler ["http-nio-8080"]
20-Sep-2018 16:30:31.719 INFO [main] org.apache.tomcat.util.net.NioSelectorPool.getSharedSelector Using a shared selector for servlet write/read
20-Sep-2018 16:30:31.732 INFO [main] org.apache.coyote.AbstractProtocol.init Initializing ProtocolHandler ["ajp-nio-8009"]
20-Sep-2018 16:30:31.735 INFO [main] org.apache.tomcat.util.net.NioSelectorPool.getSharedSelector Using a shared selector for servlet write/read
20-Sep-2018 16:30:31.736 INFO [main] org.apache.catalina.startup.Catalina.load Initialization processed in 949 ms
20-Sep-2018 16:30:31.880 INFO [main] org.apache.catalina.core.StandardService.startInternal Starting service [Catalina]
20-Sep-2018 16:30:31.880 INFO [main] org.apache.catalina.core.StandardEngine.startInternal Starting Servlet Engine: Apache Tomcat/9.0.12
20-Sep-2018 16:30:31.909 INFO [main] org.apache.coyote.AbstractProtocol.start Starting ProtocolHandler ["http-nio-8080"]
20-Sep-2018 16:30:31.930 INFO [main] org.apache.coyote.AbstractProtocol.start Starting ProtocolHandler ["ajp-nio-8009"]
20-Sep-2018 16:30:31.937 INFO [main] org.apache.catalina.startup.Catalina.start Server startup in 200 ms
Connected to server
[2018-09-20 04:30:32,156] Artifact webstore:war exploded: Artifact is being deployed, please wait...
[2018-09-20 04:30:33,434] Artifact webstore:war exploded: Artifact is deployed successfully
[2018-09-20 04:30:33,434] Artifact webstore:war exploded: Deploy took 1 278 milliseconds
20-Sep-2018 16:30:41.920 INFO [ContainerBackgroundProcessor[StandardEngine[Catalina]]] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory [C:\Users\Admin\Desktop\apache-tomcat-9.0.12\webapps\manager]
20-Sep-2018 16:30:42.028 INFO [ContainerBackgroundProcessor[StandardEngine[Catalina]]] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [C:\Users\Admin\Desktop\apache-tomcat-9.0.12\webapps\manager] has finished in [108] ms

这就是页面的样子：（我尝试了http://localhost:8080/ 和http://localhost:8080/webstore `

///编辑根据@Ce7 的帖子更新了项目。

项目结构

pom.xml

<?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>

    <groupId>com.packt</groupId>
    <artifactId>webstore</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>jstl</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.6</version>
                <configuration>
                    <warSourceDirectory>webapp</warSourceDirectory>
                    <failOnMissingWebXml>false</failOnMissingWebXml>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

web.xml

<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <servlet>
        <servlet-name>DefaultServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/DefaultServlet-servlet.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>DefaultServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

堆栈跟踪 （我不得不将它粘贴到pastebin，因为问题太长了）

https://pastebin.com/SS0uVKjU

页面

【问题讨论】：

我为什么投了反对票？

标签： java http servlets web-applications

【解决方案1】：

正确配置您的 pom，您当前的配置是创建 jar 文件，而不是 war，并且您没有 maven war 插件来将您的 web 资源（jsp、web.xml 等）放入 war 文件中。

       <groupId>com.packt</groupId>
       <artifactId>webstore</artifactId>
       <version>1.0-SNAPSHOT</version> 
       <packaging>war</packaging>

    <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-war-plugin</artifactId>
        <version>2.6</version>
        <configuration>
            <warSourceDirectory>webapp</warSourceDirectory>
            <failOnMissingWebXml>false</failOnMissingWebXml>
        </configuration>
    </plugin>

把你的WEB-INF文件夹放在根文件夹下，例如webapp/WEB-INF，这里webapp文件夹和src文件夹在同一级
将 DefaultServeletservlet.xml 重命名为

DefaultServelet-servlet.xml

修改 web.xml 文件以配置 DefaultServlet。

 <servlet>
      ...
      <init-param>
       <param-name>contextConfigLocation</param-name>
       <param-value>/WEB-INF/DefaultServlet-servlet.xml</param-value>
     </init-param>
   <load-on-startup>1</load-on-startup>
 </servlet>

完成所有这些后，部署它，然后您应该会看到如下内容：

【讨论】：

比以前更糟了。我已经更新了我的问题。看看吧。
maven 正在一个目录中寻找战争资源，在我们的例子中是 webapp 文件夹。所以你需要在根目录下创建它，并放入WEB-INF文件夹。
它工作了......终于。但我有关于 4. 点的问题。为什么我需要它以及它的作用？
这是一个我们用来配置servlet的init参数，contextConfigLocation参数告诉servlet去哪里找上下文配置，servlet会使用配置文件（DeafaultServlet-servlet.xml）来创建web应用语境。如果查看源代码，它是DispatcherServlet的父类FrameworkServlet中的一个类字段。你应该能够看到它是如何使用的。

【解决方案2】：

上面的问题是您将servlet configuration file命名为DefaultServletservlet.xml。

您应该将rename 改为DefaultServlet-servlet.xml。在检查xml configuration 时，弹簧匹配以-servlet 作为后缀的文件名。因为找不到DefaultServlet-servlet.xml，所以报错。

【讨论】：

没有任何改变。我将DefaultServletservlet.xml 重命名为DefaultServlet-servlet.xml
但你是对的 - 不见了。不幸的是，仍然不起作用:(
奇怪。它在我的机器上工作。您可以尝试清理tomcat工作目录并重新构建吗？并检查目录中是否创建了webstore.war。
我已经清理了 tomcat 工作目录。还是不行。 .war 文件应该出现在工件上？我编辑了我的问题，在其中添加了更新的项目结构。
运行maven包后目标文件夹中应该出现.war文件