Jsf javax.faces.el.EvaluationException:java.lang.NoClassDefFoundError:javax/persistence/persistence

对于我正在进行的一个项目，我在Eclipse上使用JPA和JSF。最初我开发了数据层（数据库中的access），它工作得很好。但是，当我将其与JSF项目集成并尝试通过bean连接到db时，我遇到了以下异常：

com.sun.faces.application.ActionListenerImpl processAction 严重：java.lang.NoClassDefFoundError:javax/persistence/persistence

特别是当它试图获取entitymanager工厂时崩溃

EntityManagerFactory emf = Persistence.createEntityManagerFactory("ResearchManagement.Data");
        EntityManager em = emf.createEntityManager();
        em.getTransaction().begin();

我已经包括了所有必需的库，包括javax/persistence。 我不明白为什么我会犯这个错误。 下面您可以看到完整的异常堆栈，以及我包含的库的图像

有人能告诉我我做错了什么吗？我也看了其他类似的问题，但没有解决我的问题。 谢谢你们

 SEVERE: java.lang.NoClassDefFoundError: javax/persistence/Persistence
javax.faces.el.EvaluationException: java.lang.NoClassDefFoundError: javax/persistence/Persistence
    at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:98)
    at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:98)
    at javax.faces.component.UICommand.broadcast(UICommand.java:311)
    at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:781)
    at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1246)
    at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:77)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:97)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:114)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:308)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:307)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NoClassDefFoundError: javax/persistence/Persistence
    at org.ResearchManagement.Handlers.UserHandler.getAllUsers(UserHandler.java:31)
    at org.tutorial.LoginBean.authenticate(LoginBean.java:48)
    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.apache.el.parser.AstValue.invoke(AstValue.java:264)
    at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:278)
    at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:102)
    at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:84)
    ... 24 more
Caused by: java.lang.ClassNotFoundException: javax.persistence.Persistence
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    ... 34 more
11 Οκτ 2012 6:55:10 μμ com.sun.faces.lifecycle.InvokeApplicationPhase execute
WARNING: #{loginBean.authenticate}: java.lang.NoClassDefFoundError: javax/persistence/Persistence
javax.faces.FacesException: #{loginBean.authenticate}: java.lang.NoClassDefFoundError: javax/persistence/Persistence
    at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:114)
    at javax.faces.component.UICommand.broadcast(UICommand.java:311)
    at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:781)
    at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1246)
    at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:77)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:97)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:114)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:308)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:307)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: javax.faces.el.EvaluationException: java.lang.NoClassDefFoundError: javax/persistence/Persistence
    at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:98)
    at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:98)
    ... 23 more
Caused by: java.lang.NoClassDefFoundError: javax/persistence/Persistence
    at org.ResearchManagement.Handlers.UserHandler.getAllUsers(UserHandler.java:31)
    at org.tutorial.LoginBean.authenticate(LoginBean.java:48)
    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.apache.el.parser.AstValue.invoke(AstValue.java:264)
    at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:278)
    at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:102)
    at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:84)
    ... 24 more
Caused by: java.lang.ClassNotFoundException: javax.persistence.Persistence
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    ... 34 more

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这些JAR文件需要放到

/WEB-INF/lib

文件夹中，而不是手动添加到项目的构建路径属性中

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撤消在项目的Build Path属性中所做的每一项更改（重新创建项目可能更容易），并放置webapp所依赖的JAR文件（容器本身尚未提供）直接进入

/WEB-INF/lib

文件夹，而不篡改/修改任何IDE项目设置。

NoClassDefFoundError是由于运行时缺少类定义造成的

我有一个非常类似的问题，但我使用的是Jdeveloper。 当我添加一个外部库时，我忘了选中“Deployedbydefault”选项，所以我认为添加的jar文件在运行之前可能不会被部署

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我不知道eclipse中是否有“默认部署”选项，但我建议您在添加库时寻找类似的选项

我按照您的建议做了，但仍然得到相同的错误：（.我甚至将库放在Tomcat lib文件夹中，但仍然没有。还有其他想法吗？