投射 Dispatcher Servlet 的异常答案

【问题标题】：Exception on casting Dispatcher Servlet投射 Dispatcher Servlet 的异常
【发布时间】：2014-02-01 01:29:45
【问题描述】：

我在 Eclipse 中有一个 Maven 网络，在编译它时，我收到一些异常说 java.lang.ClassCastException: org.springframework.web.servlet.DispatcherServlet cannot be cast to javax.servlet.Servlet 我无法理解异常，也不知道出了什么问题。

pom.xml：

<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>saumyaraj</groupId>
  <artifactId>wishtree</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>war</packaging>
  <dependencies>
  <dependency>
    <groupId>javax.persistence</groupId>
    <artifactId>persistence-api</artifactId>
    <version>1.0.2</version>
    </dependency>
    <dependency>
    <groupId>javax</groupId>
    <artifactId>javaee-api</artifactId>
    <version>7.0</version>
      <scope>provided</scope>
</dependency>     
      <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>4.0.0.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-beans</artifactId>
    <version>4.0.0.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-core</artifactId>
    <version>4.2.8.Final</version>
</dependency>          
  <dependency>
    <groupId>javax.transaction</groupId>
    <artifactId>javax.transaction-api</artifactId>
    <version>1.2</version>
</dependency>
   <dependency>
    <groupId>maven-taglib</groupId>
    <artifactId>maven-taglib-plugin</artifactId>
    <version>1.4.2</version>
</dependency>
</dependencies>
</project>

我的 web.xml:-

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    id="WebApp_ID" version="2.5">
    <display-name>Spring3-Hibernate</display-name>
   <!--  <welcome-file-list>
        <welcome-file>index.html</welcome-file>
    </welcome-file-list> -->
    <servlet>
        <servlet-name>spring</servlet-name>
        <servlet-class>
            org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>spring</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

错误堆栈：-

SEVERE: Servlet /wishtree threw load() exception
java.lang.ClassCastException: org.springframework.web.servlet.DispatcherServlet cannot be cast to javax.servlet.Servlet
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1116)
    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:993)
    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4350)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4659)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:785)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:445)
    at org.apache.catalina.startup.Embedded.start(Embedded.java:825)
    at org.codehaus.mojo.tomcat.AbstractRunMojo.startContainer(AbstractRunMojo.java:558)
    at org.codehaus.mojo.tomcat.AbstractRunMojo.execute(AbstractRunMojo.java:255)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:106)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:208)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:317)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:152)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:555)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:214)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:158)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
    at org.codehaus.classworlds.Launcher.main(Launcher.java:46)

请帮忙。

【问题讨论】：

好像不是你pom.xml的问题，而是你web.xml的问题
可能是您在代码中将 org.springframework.web.servlet.DispatcherServlet 转换为 javax.servlet.Servlet 吗？ org.springframework.web.servlet.DispatcherServlet 扩展 javax.servlet.http.HttpServlet。
@Rugal 我已经用 web.xml 编辑了这个问题
@SergeyMorozov 对不起，我没有得到你。
@saumyaraj 你自己有代码吗？你在你的代码中投射它吗？请提供您的错误堆栈

标签： java maven spring-mvc servlets dispatcher

【解决方案1】：

假设您使用的是 mojo-pugin 1.1 版，如 here 所示，那么您的 Tomcat Servlet 容器是 6.0.29 版，并且具有较旧版本的 servlet-api (Java EE 6)。您的 Spring version 4 DispatcherServlet 使用新版本的 servlet-api (Java EE 7) 进行编译。

您要么需要使用旧版本的 Spring 或新版本的 mojo（我找不到。）

或者，您可以获取 mojo 项目并使用更新版本的 org.apache.tomcat 库重新编译它。

【讨论】：