Maven部署過程中的ClassCastException問題
引言: Maven功能強大,但是又有些複雜,難以捉摸和使用。在本人開發中碰到了一個ClassCastException的問題,通過這個問題的解決,加深了對於maven依賴管理中scope的理解。
1. 問題的引入
部署環境tomcat 7, 開發中使用的框架spring,spring data,hibernate之類的,基於Maven部署過程中,會出現以下異常資訊:
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. 問題分析
這幾個Servlet都是在web.xml中配置的Filter,其配置沒有問題。錯誤型別為ClassCastException, 就是其實現的Filter與目標的Filter存在不同,就是說有可能是類庫引用的不同,導致在啟動過程中,出現這樣的問題。
3. 檢視pom.xml
在開發中,引入瞭如下包,用以解決Servlet/JSP中常用類庫的引用問題,這些都是在Web伺服器中實現的類庫。
這裡可以看到,jsp/servlet將在整個的打包部署宣告週期中被用到,並被打包到部署環境中。<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>
4. 問題的解決
由於無法預知最終部署的Web伺服器的版本和型別,故這裡的這兩個依賴在編譯、測試中會用到,但是在部署環境中,是不能打包到部署環境中去的。
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的含義和使用
<dependency>中<scope>,它主要管理依賴的部署。目前<scope>可以使用5個值:
* compile,預設值,適用於所有階段,會隨著專案一起釋出。
* provided,類似compile,期望JDK、容器或使用者會提供這個依賴。如servlet.jar。
* runtime,只在執行時使用,如JDBC驅動,適用執行和測試階段。
* test,只在測試時使用,用於編譯和執行測試程式碼。不會隨專案釋出。
* system,類似provided,需要顯式提供包含依賴的jar,Maven不會在Repository中查詢它。
依賴範圍(scope) | 主原始碼classpath可用 | 測試原始碼classpath可用 | 會被打包 |
compile 預設值 | TRUE | TRUE | TRUE |
test | FALSE | TRUE | FALSE |
runtime | FALSE | TRUE | TRUE |
provided | TRUE | TRUE | FALSE |