Maven部署过程中的ClassCastException问题

灰太狼 2022-08-06 15:04 120阅读 0赞

引言： Maven功能强大，但是又有些复杂，难以捉摸和使用。在本人开发中碰到了一个ClassCastException的问题，通过这个问题的解决，加深了对于maven依赖管理中scope的理解。

1. 问题的引入

部署环境tomcat 7， 开发中使用的框架spring,spring data,hibernate之类的，基于Maven部署过程中，会出现以下异常信息：

SEVERE: Exception starting filter Spring OpenEntityManagerInViewFilter
    java.lang.ClassCastException: org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter cannot be cast to javax.servlet.Filter
    	at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:275)
    	at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:422)
    	at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:115)
    	at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4001)
    	at org.apache.catalina.core.StandardContext.start(StandardContext.java:4651)
    	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:132)
    	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:116)
    	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
    	at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
    	at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:120)
    	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:347)
    	at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:154)
    	at org.apache.maven.cli.MavenCli.execute(MavenCli.java:582)
    	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(NativeMethodAccessorImpl.java:39)
    	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    	at java.lang.reflect.Method.invoke(Method.java:597)
    	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)
    Feb 3, 2015 1:36:32 PM org.apache.catalina.core.StandardContext filterStart
    SEVERE: Exception starting filter Set Character Encoding
    java.lang.ClassCastException: org.springframework.web.filter.CharacterEncodingFilter cannot be cast to javax.servlet.Filter
    	at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:275)
    	at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:422)
    	at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:115)
    	at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4001)
    	at org.apache.catalina.core.StandardContext.start(StandardContext.java:4651)
    	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:132)
    	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:116)
    	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
    	at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
    	at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:120)
    	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:347)
    	at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:154)
    	at org.apache.maven.cli.MavenCli.execute(MavenCli.java:582)
    	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(NativeMethodAccessorImpl.java:39)
    	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    	at java.lang.reflect.Method.invoke(Method.java:597)
    	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)
    Feb 3, 2015 1:36:32 PM org.apache.catalina.core.StandardContext filterStart
    SEVERE: Exception starting filter HiddenHttpMethodFilter
    java.lang.ClassCastException: org.springframework.web.filter.HiddenHttpMethodFilter cannot be cast to javax.servlet.Filter
    	at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:275)
    	at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:422)
    	at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:115)
    	at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4001)
    	at org.apache.catalina.core.StandardContext.start(StandardContext.java:4651)
    	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:132)
    	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:116)
    	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
    	at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
    	at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:120)
    	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:347)
    	at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:154)
    	at org.apache.maven.cli.MavenCli.execute(MavenCli.java:582)
    	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(NativeMethodAccessorImpl.java:39)
    	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    	at java.lang.reflect.Method.invoke(Method.java:597)
    	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)
    Feb 3, 2015 1:36:32 PM org.apache.catalina.core.StandardContext start
    SEVERE: Error filterStart
    Feb 3, 2015 1:36:32 PM org.apache.catalina.core.StandardContext start
    SEVERE: Context [/bsettle] startup failed due to previous errors

2. 问题分析

这几个Servlet都是在web.xml中配置的Filter，其配置没有问题。错误类型为ClassCastException, 就是其实现的Filter与目标的Filter存在不同，就是说有可能是类库引用的不同，导致在启动过程中，出现这样的问题。

3. 查看pom.xml

在开发中，引入了如下包，用以解决Servlet/JSP中常用类库的引用问题，这些都是在Web服务器中实现的类库。

<dependency>
    			<groupId>org.apache.tomcat</groupId>
    			<artifactId>tomcat-servlet-api</artifactId>
    			<version>7.0.56</version>
    		</dependency>
    
    		<dependency>
    			<groupId>org.apache.tomcat</groupId>
    			<artifactId>tomcat-jsp-api</artifactId>
    			<version>7.0.57</version>			
    		</dependency>

这里可以看到，jsp/servlet将在整个的打包部署声明周期中被用到，并被打包到部署环境中。

4. 问题的解决

由于无法预知最终部署的Web服务器的版本和类型，故这里的这两个依赖在编译、测试中会用到，但是在部署环境中，是不能打包到部署环境中去的。

故需要做如下修改：

<dependency>
    			<groupId>org.apache.tomcat</groupId>
    			<artifactId>tomcat-servlet-api</artifactId>
    			<version>7.0.56</version>
    			<scope>provided</scope>
    		</dependency>
    		<dependency>
    			<groupId>org.apache.tomcat</groupId>
    			<artifactId>tomcat-jsp-api</artifactId>
    			<version>7.0.57</version>			
    			<scope>provided</scope>
    		</dependency>

5. Scope的含义和使用

<dependency>中<scope>，它主要管理依赖的部署。目前<scope>可以使用5个值：   
    \* compile，缺省值，适用于所有阶段，会随着项目一起发布。   
    \* provided，类似compile，期望JDK、容器或使用者会提供这个依赖。如servlet.jar。   
    \* runtime，只在运行时使用，如JDBC驱动，适用运行和测试阶段。   
    \* test，只在测试时使用，用于编译和运行测试代码。不会随项目发布。   
    \* system，类似provided，需要显式提供包含依赖的jar，Maven不会在Repository中查找它。

<table style="color:rgb(0,0,0); font-size:16px; line-height:24px"> 
 <tbody> 
  <tr> 
   <td style="font-size:1em">依赖范围（scope）</td> 
   <td style="font-size:1em">主源码classpath可用</td> 
   <td style="font-size:1em">测试源码classpath可用</td> 
   <td style="font-size:1em">会被打包</td> 
  </tr> 
  <tr> 
   <td style="font-size:1em">compile 缺省值</td> 
   <td style="font-size:1em">TRUE</td> 
   <td style="font-size:1em">TRUE</td> 
   <td style="font-size:1em">TRUE</td> 
  </tr> 
  <tr> 
   <td style="font-size:1em">test</td> 
   <td style="font-size:1em">FALSE</td> 
   <td style="font-size:1em">TRUE</td> 
   <td style="font-size:1em">FALSE</td> 
  </tr> 
  <tr> 
   <td style="font-size:1em">runtime</td> 
   <td style="font-size:1em">FALSE</td> 
   <td style="font-size:1em">TRUE</td> 
   <td style="font-size:1em">TRUE</td> 
  </tr> 
  <tr> 
   <td style="font-size:1em">provided</td> 
   <td style="font-size:1em"><span style="font-weight:bold; color:rgb(226,136,34); background-color:rgb(255,255,0)">TRUE</span></td> 
   <td style="font-size:1em">TRUE</td> 
   <td style="font-size:1em">FALSE</td> 
  </tr> 
 </tbody> 
</table>