java.lang.ClassNotFoundException:javax.servlet.jsp.el.ImplicitObjectELResolver $ ImplicitObjects

Question

升级到最新版本的eclipse Helios 3.6,M2E 1.0,WTP 3.2.5 并尝试在tomcat 7上运行使用JSF 2.1.3和Spring 3的 maven项目后,我收到以下异常:

java.lang.ClassNotFoundException: javax.servlet.jsp.el.ImplicitObjectELResolver$ImplicitObjects$4
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1678)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1523)
    at org.apache.catalina.startup.ContextConfig.checkHandlesTypes(ContextConfig.java:2006)
    at org.apache.catalina.startup.ContextConfig.processAnnotationsStream(ContextConfig.java:1969)
    at org.apache.catalina.startup.ContextConfig.processAnnotationsJar(ContextConfig.java:1858)
    at org.apache.catalina.startup.ContextConfig.processAnnotationsUrl(ContextConfig.java:1826)
    at org.apache.catalina.startup.ContextConfig.processAnnotations(ContextConfig.java:1812)
    at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1306)
    at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:896)
    at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:322)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
    at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5103)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:148)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1033)
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:774)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:148)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1033)
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:291)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:148)
    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:148)
    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:727)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:148)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:621)
    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.apache.catalina.startup.Bootstrap.start(Bootstrap.java:322)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:450)

java.lang.LinkageError: loader constraint violation: when resolving interface method "javax.servlet.jsp.JspApplicationContext.getExpressionFactory()Ljavax/el/ExpressionFactory;" the class loader (instance of org/apache/catalina/loader/WebappClassLoader) of the current class, com/sun/faces/config/ConfigureListener, and the class loader (instance of org/apache/catalina/loader/StandardClassLoader) for resolved class, javax/servlet/jsp/JspApplicationContext, have different Class objects for the type javax/el/ExpressionFactory used in the signature
    at com.sun.faces.config.ConfigureListener.registerELResolverAndListenerWithJsp(ConfigureListener.java:693)
    at com.sun.faces.config.ConfigureListener.contextInitialized(ConfigureListener.java:243)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4723)
    at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5226)
    at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5221)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
    at java.util.concurrent.FutureTask.run(FutureTask.java:138)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    at java.lang.Thread.run(Thread.java:662)
Dec 17, 2011 4:56:04 PM org.apache.catalina.core.StandardContext listenerStart
SEVERE: Exception sending context initialized event to listener instance of class com.sun.faces.config.ConfigureListener
java.lang.RuntimeException: java.lang.LinkageError: loader constraint violation: when resolving interface method "javax.servlet.jsp.JspApplicationContext.getExpressionFactory()Ljavax/el/ExpressionFactory;" the class loader (instance of org/apache/catalina/loader/WebappClassLoader) of the current class, com/sun/faces/config/ConfigureListener, and the class loader (instance of org/apache/catalina/loader/StandardClassLoader) for resolved class, javax/servlet/jsp/JspApplicationContext, have different Class objects for the type javax/el/ExpressionFactory used in the signature
    at com.sun.faces.config.ConfigureListener.contextInitialized(ConfigureListener.java:292)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4723)
    at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5226)
    at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5221)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
    at java.util.concurrent.FutureTask.run(FutureTask.java:138)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.LinkageError: loader constraint violation: when resolving interface method "javax.servlet.jsp.JspApplicationContext.getExpressionFactory()Ljavax/el/ExpressionFactory;" the class loader (instance of org/apache/catalina/loader/WebappClassLoader) of the current class, com/sun/faces/config/ConfigureListener, and the class loader (instance of org/apache/catalina/loader/StandardClassLoader) for resolved class, javax/servlet/jsp/JspApplicationContext, have different Class objects for the type javax/el/ExpressionFactory used in the signature
    at com.sun.faces.config.ConfigureListener.registerELResolverAndListenerWithJsp(ConfigureListener.java:693)
    at com.sun.faces.config.ConfigureListener.contextInitialized(ConfigureListener.java:243)
    ... 8 more

以下是我对maven的配置:

<dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.0.1</version>
        <scope>provided</scope>
       </dependency>


        <dependency>
         <groupId>com.sun.faces</groupId>
         <artifactId>jsf-api</artifactId>
         <version>2.1.3</version>
        </dependency>

        <dependency>
         <groupId>com.sun.faces</groupId>
         <artifactId>jsf-impl</artifactId>
         <version>2.1.3</version>
        </dependency>

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

我错过了一个jar文件,还是使用了一个不兼容的jar版本？

请指教,谢谢.

更新:到目前为止我得到的是通过从pom文件中删除以下依赖项来使应用程序正常运行:

<dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>javax.servlet.jsp-api</artifactId>
            <version>2.2.1</version>
           <scope>provided</scope>
          </dependency>

          <dependency>
           <groupId>javax.el</groupId>
            <artifactId>javax.el-api</artifactId>
           <version>2.2.2</version>
           <scope>provided</scope>
          </dependency>

我认为他们与容器提供的罐子相冲突.

我需要知道的是:

1 -我一定要添加依赖关系:javax.servlet.jsp-api,javax.el-api我的POM文件所规定或者我不需要它们添加呢？

2-如果我必须添加这两个依赖项,那么我应该如何正确地添加它们以便它们不会与tomcat jar冲突,这意味着什么版本,我应该标记依赖项是否提供？

并且重要的问题是,如果我必须添加它们,为什么我必须这样做,添加它们的重要性是什么,因为它们是由容器提供的,我到目前为止所理解的是,我需要添加javax.servlet-api依赖项并标记它因为我在某些类中使用servlet.

Answer 1

仅当您在代码中需要这些依赖项（这意味着编译代码时需要它们）时，才应添加这些依赖项。如果您的代码中不使用 JSP 或 EL 类，则可以删除依赖项。因此，您可以通过删除依赖项来测试是否需要依赖项。如果您的代码仍然可以编译，则不需要它们。:)

如果您需要它们，您绝对应该将它们添加为provided依赖项，因为这些类是由 Tomcat 在运行时提供的。只需确保依赖项的版本与 Tomcat 提供的版本匹配即可。那么你就不会有任何问题了。提供的依赖项仅用于编译代码，但它们不会打包到生成的 WAR 文件中，这是可以的，因为 Tomcat 提供了它们。