开始配置TOMCAT时出现如下错误,是怎么回事>

HTTP Status 500 - --------------------------------------------------------------------------------type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException: Unable to compile class for JSPAn error occurred at line: -1 in the jsp file: nullGenerated servlet error:
    [javac] Compiling 1 source file at org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:85)
at org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:248)
at org.apache.jasper.compiler.Compiler.generateClass(Compiler.java:343)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:356)
at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:427)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:142)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:240)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:187)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:809)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:198)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:144)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:209)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:595)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:432)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:954)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:138)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:595)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:432)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:954)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2459)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:132)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:595)
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:118)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:593)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:116)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:593)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:432)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:954)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:126)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:595)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:432)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:954)
at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:152)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Unknown Source)--------------------------------------------------------------------------------Apache Tomcat/4.1.34