使用TomcatPlugin,常见异常之一。
在整合struts时，原以为只是简单的配上就能跑，结果发现抛了个异常，没想清楚是怎么回事，然后认真地检查了下配置，原来如此啊。
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异常如下：
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Struts Problem ReportStruts has detected an unhandled exception:Messages:java.lang.NullPointerExceptionFile:org/apache/jsp/error_jsp.javaLine number:23Stacktracesorg.apache.jasper.JasperException: java.lang.NullPointerException org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:570) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:383) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334) javax.servlet.http.HttpServlet.service(HttpServlet.java:722) org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:684) org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:471) org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:402) org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:329) org.apache.struts2.dispatcher.ServletDispatcherResult.doExecute(ServletDispatcherResult.java:157) org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:186) com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:373) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:277) org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52) org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:498) org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77) org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91) org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240) org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164) org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:498) org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562) org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:394) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243) org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188) org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302) java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) java.lang.Thread.run(Thread.java:662) java.lang.NullPointerException org.apache.jsp.error_jsp._jspInit(error_jsp.java:23) org.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:49) org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:171) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:356) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334) javax.servlet.http.HttpServlet.service(HttpServlet.java:722) org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:684) org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:471) org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:402) org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:329) org.apache.struts2.dispatcher.ServletDispatcherResult.doExecute(ServletDispatcherResult.java:157) org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:186) com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:373) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:277) org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52) org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:498) org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77) org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91) org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240) org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164) org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:498) org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562) org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:394) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243) org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188) org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302) java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) java.lang.Thread.run(Thread.java:662)
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发现,JSP初始化的时候就出了问题,一般出现这样的问题多半是少包了，或是多了包（冲突）。
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于是把tomcatplugin选择的classpath中的jsp-api-**,去掉了试了下,果然好了。
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于是猜想,如果加上servlet-api-**恐怕也会出问题吧。。。。。
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因为在TOMCAT/lib/目录下,已经有servlet-api.jar和jsp-api.jar,启动项目的时候,到底用哪一个呢,这个不好说了。。
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没研究过,应该会冲突出问题吧,如果版本不一致的话。
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