问个TOMCAT的环境问题?急!

我在HTTP://127.0.0.1:8080可以正常显示页面,我把自己写的JSP文件放在TOMACAT安装目录下的webapps/root下,运行的结果是:
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)
sun.reflect.GeneratedMethodAccessor60.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Unknown Source)
org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:239)
java.security.AccessController.doPrivileged(Native Method)
javax.security.auth.Subject.doAsPrivileged(Unknown Source)
org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:268)
org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:157)

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)
sun.reflect.GeneratedMethodAccessor60.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Unknown Source)
org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:239)
java.security.AccessController.doPrivileged(Native Method)
javax.security.auth.Subject.doAsPrivileged(Unknown Source)
org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:268)
org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:157)

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

--------------------------------------------------------------------------------

Apache Tomcat/5.0.28

请问是什么原因呀?多谢各位大哥了!

----------------解决方案--------------------------------------------------------
我也遇到了同样得问题，哪位大侠帮帮忙阿
----------------解决方案--------------------------------------------------------

你在地址中输入的是什么.
http://127.0.0.1:8080/jspfilename.jsp
是这样么

你最好先放一个最简单的jsp文件来实验.

----------------解决方案--------------------------------------------------------
要么是.xml文件的问题！
最好是先在这个文件下。。/webapps/建一个myweb文件先试试

----------------解决方案--------------------------------------------------------