Why jsp page cause exceptions in J2EE App. Server

Question

I installed j2ee App Server on my Windows 2000, wrote a simple .jsp, moved the code to domains\domain1\docroot, ran the .jsp from the browser and saw the following exception. I could not find the directory common/lib for my Tomcat server. Please instruct.
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
No Java compiler was found to compile the generated source for the JSP.
This can usually be solved by copying manually $JAVA_HOME/lib/tools.jar from the JDK
to the common/lib directory of the Tomcat server, followed by a Tomcat restart.
If using an alternate Java compiler, please check its installation and access path.
     org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:132)
     org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:356)
     org.apache.jasper.compiler.Compiler.generateClass(Compiler.java:420)
     org.apache.jasper.compiler.Compiler.compile(Compiler.java:463)
     org.apache.jasper.compiler.Compiler.compile(Compiler.java:444)
     org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:557)
     org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:305)
     org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:306)
     org.apache.jasper.servlet.JspServlet.service(JspServlet.java:253)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:861)
     sun.reflect.GeneratedMethodAccessor71.invoke(Unknown Source)
     sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     java.lang.reflect.Method.invoke(Method.java:324)
     org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:289)
     java.security.AccessController.doPrivileged(Native Method)
     javax.security.auth.Subject.doAsPrivileged(Subject.java:500)
     org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:311)
     org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:205)
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Answer 1

This is a known issue.
The error message about the missing Java compiler is very misleading, and
is being caused by a bug in the way compilation error messages are
being propagated.
Following is a detailed explanation of the behaviour you are seeing:
The misleading error message is printed only in the case where a javac
compilation error line number cannot be mapped back to a line number
in the JSP source code.
The internal representation of a JSP element ("JSP node") in the JSP compiler
contains the following info:
- The begin line number of the JSP element in the JSP page
- The begin and end line numbers ("range") of the Java code that was
generated for the JSP element
When attempting to map a javac error line number back to the JSP
source line, we determine the range into which the javac error line
number falls, and retrieve the JSP source number of the JSP element
associated with that range.
However, in some cases, it is impossible to trace a javac error line
number back to the JSP element that caused the error. For example,
consider the following scriptlet:
<%
String query = request.getParameter("query");
if(query != null) {
out.println(query);
} else {
out.println("(null)");
// } // <-- !Missing brace syntax error
%>
Since the JSP compiler wraps the generated code into a
try-catch-finally block, the above syntax error in the scriptlet
causes havoc with that try-catch-finally block, and results in 3 javac
errors:
<file>jsp.java:<line1>: 'catch' without 'try'
} catch (Throwable t) {
^
<file>jsp.java:<line2>: 'try' without 'catch' or 'finally'
try {
^
<file>jsp.java:<line3>: '}' expected
Notice that all of the above javac error numbers are outside the range
of the java line numbers corresponding to the scriptlet that caused the
error, and therefore cannot be mapped back to any line numbers in the
JSP page source.
AS 8.0 PE does not handle this case correctly, and prints out the
misleading error message (though the real error message can be found
in the server log).
Notice that this problem is going to be fixed in AS 8.1, so that if a
javac error line number cannot be mapped back to a JSP page line
number, the javac error is still returned to the client.
As far as your particular JSP page is concerned, I don't see anything
wrong with it, and it compiles just fine for me.
Do you still have any problems with it?
Jan