我装了JDK 和 TOMCAT 5.0 ,以前在朋友机子上装的时候很顺利就OK了,今天在我自己的机子上装,装上可以,TOMCAT的首页可以显示,HTML的页面也可以显示,但是在显示带有JSP代码的页面的时候就出现错误,错误如下:

HTTP Status 500 -

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: Unable to compile class for JSP
	org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:97)
	org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:346)
	org.apache.jasper.compiler.Compiler.generateClass(Compiler.java:414)
	org.apache.jasper.compiler.Compiler.compile(Compiler.java:472)
	org.apache.jasper.compiler.Compiler.compile(Compiler.java:451)
	org.apache.jasper.compiler.Compiler.compile(Compiler.java:439)
	org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:511)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:295)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

root cause

Unable to find a javac compiler;
com.sun.tools.javac.Main is not on the classpath.
Perhaps JAVA_HOME does not point to the JDK
	org.apache.tools.ant.taskdefs.compilers.CompilerAdapterFactory.getCompiler(CompilerAdapterFactory.java:106)
	org.apache.tools.ant.taskdefs.Javac.compile(Javac.java:935)
	org.apache.tools.ant.taskdefs.Javac.execute(Javac.java:764)
	org.apache.jasper.compiler.Compiler.generateClass(Compiler.java:382)
	org.apache.jasper.compiler.Compiler.compile(Compiler.java:472)
	org.apache.jasper.compiler.Compiler.compile(Compiler.java:451)
	org.apache.jasper.compiler.Compiler.compile(Compiler.java:439)
	org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:511)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:295)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

note The full stack trace of the root cause is available in the Apache Tomcat/5.0.28 logs.

请高手帮忙解决,小弟先谢了!(JDK和TOMCAT的环境变量我都设置好了，我真想不出其他的原因拉!)