Craig,
Thanks again for the information.
The info. you've supplied has been very useful.
However, my problem remains:
I cannot access the class that resides in a JAR file (utilities.jar) in
<tomcat_home>/shared/lib and get a java.lang.NoClassDefFoundError
I am spinning my wheels on this so hopefully some details will shed some light on my
problem. I wrote a very simple servlet that attempts to use the class in the shared
dir.
----
import com.myco.utilities.CASDate;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class Test1 extends HttpServlet {
//
public void doGet(HttpServletRequest request, HttpServletResponse response) throws
javax.servlet.ServletException, java.io.IOException {
System.out.println("GET method of Test1 invloked");
performTask(request, response);
}
//
public void doPost(HttpServletRequest request, HttpServletResponse response) throws
javax.servlet.ServletException, java.io.IOException {
System.out.println("POST method of Test1 invloked");
performTask(request, response);
}
/**
* Test the use of a shared class.
*/
public void performTask(HttpServletRequest request, HttpServletResponse response) {
try {
java.io.PrintWriter pw = response.getWriter();
CASDate today = new CASDate();
pw.println("CASDate today is " + today.toString());
pw.println("CASDate class loaded...");
}
catch(Throwable theException) {
System.out.println("Error...");
theException.printStackTrace(System.out);
}
}
}
----
This is the utility class (some getXXX methods deleted for brevity):
----
package com.myco.utilities;
import java.util.Calendar;
import java.util.GregorianCalendar;
public class CASDate {
private int ccc = 0;
private int yyy = 0;
private int mmm = 0;
private int ddd = 0;
private int time = 0;
/**
* Default constructor is to create CAS date using the current date.
*/
public CASDate() {
super();
GregorianCalendar cal = new GregorianCalendar();
ccc = 20;
yyy = cal.get(Calendar.YEAR) - 2000;
mmm = cal.get(Calendar.MONTH) + 1;
ddd = cal.get(Calendar.DAY_OF_MONTH);
}
/**
* Return a string in MM/DD/CCYY format.
*/
public String toString() {
String returnValue = getMonth() + "/" + getDay() + "/" + getYearAndCentury();
return returnValue;
}
}
----
The error I get is:
java.lang.NoClassDefFoundError: com/myco/utilities/CASDate
When I moved utilities.jar to <webapp>/WEB-INF/lib the error goes away.
I hope this provides some clues as to what is going wrong. At this point it looks like
a bug but I hope I'm wrong. I am using Tomcat 4.1.18.
Any help is GREATLY appreciated.
Thanks,
Todd
-----Original Message-----
From: "Craig R. McClanahan"<[EMAIL PROTECTED]>
To: "Pat McGroin"<[EMAIL PROTECTED]>
Date: Thu Mar 27 13:53:24 PST 2003
Subject: Re: shared resources
>
>
>On Thu, 27 Mar 2003, Pat McGroin wrote:
>
>> Date: Thu, 27 Mar 2003 12:57:03 -0800 (PST)
>> From: Pat McGroin <[EMAIL PROTECTED]>
>> To: Craig R. McClanahan <[EMAIL PROTECTED]>
>> Subject: Re: Re: shared resources
>>
>> Craig,
>>
>> Thanks very much for the detailed reply.
>> That is very useful information for getting at resource files.
>> However, my problem is much simpler. I am simply getting
>> java.lang.NoClassDefFoundError errors when I try to use classes in JAR files in the
>> <tomcat_home>/shared/lib directory.
>> When I move the jar files to my <webapp root>/WEB-INF/lib the classes are loaded
>> just fine and I don't see these errors.
>>
>
>One likely cause for this sort of thing: if a class in your "problem
>child" JAR file is itself loaded from the shared class loader, but tries
>to access a different class that is in the webapp class loader, you'll get
>exactly this sort of problem.
>
>Note that NoClassDefFound errors do *not* say that the class named in the
>exception report cannot be found (that would be a ClassNotFoundException).
>Instead, it means that one of the classes that this class depends on
>cannot be found.
>
>> Thanks,
>> Todd
>
>Craig
>
>>
>>
>> -----Original Message-----
>> From: "Craig R. McClanahan"<[EMAIL PROTECTED]>
>> To: "Tomcat Users List"<[EMAIL PROTECTED]>
>> Date: Thu Mar 27 12:33:57 PST 2003
>> Subject: Re: shared resources
>>
>> >
>> >
>> >On Thu, 27 Mar 2003, Pat McGroin wrote:
>> >
>> >> Date: Thu, 27 Mar 2003 11:20:49 -0800 (PST)
>> >> From: Pat McGroin <[EMAIL PROTECTED]>
>> >> Reply-To: Tomcat Users List <[EMAIL PROTECTED]>
>> >> To: [EMAIL PROTECTED]
>> >> Subject: shared resources
>> >>
>> >> Hello.
>> >>
>> >> I am trying to reference a few JAR files from an out-of-process Tomcat
>> >> 4.1.18 application.
>> >>
>> >> The Tomcat 4.1 documentation says that unpacked shared classes and
>> >> resources will be loaded out of the <tomcat_root>/shared/classes
>> >> directory and packed shared resources are loaded out of
>> >> <tomcat_root>/shared/lib:
>> >>
>> >> http://jakarta.apache.org/tomcat/tomcat-4.1-doc/class-loader-howto.html
>> >>
>> >> I put a few JAR files in <tomcat_root>/shared/lib but they are never
>> >> loaded. I can move them into my <webapp root>/WEB-INF/lib and they are
>> >> loaded without problems.
>> >>
>> >> Am I misunderstanding how resources are found in Tomcat 4.1? The
>> >> context I am using is not within <tomcat_home>/webapps. It is in an
>> >> entirely diferent directory. Could that be the problem?
>> >>
>> >> I posted a simliar question a few days ago but was not yet properly
>> >> subscribed so I apologize for the duplication.
>> >>
>> >> Thanks in advance for any help!
>> >>
>> >
>> >When accessing resources with getResource()/getResourceAsStream(), it is
>> >important to remember that there are two different implementations of
>> >these things, which operate quite differently:
>> >
>> >ServletContext.getResource() and ServletContext.getResourceAsStream():
>> >* Can be used to access static resources within your web application
>> >* Resources is specified as a context-relative URI starting with "/"
>> >* For example, to read the web.xml file as a resource, you would use
>> > a resource path of "/WEB-INF/web.xml"
>> >* It doesn't matter whether your webapp is running from an unpacked
>> > directory or a WAR file, or where the directory/WAR is actually
>> > located.
>> >
>> >ClassLoader.getResource() and ClassLoader.getResourceAsStream():
>> >* Can be used to access resources embedded within the class loader
>> > (or class loader hierarchy)
>> >* For a standalone app, that means somewhere on your classpath
>> >* For a webapp installed in Tomcat 4.1, and assuming you're starting
>> > with the webapp class loader, it checks there and up the hierarchy
>> > as described in the Tomcat documentation.
>> >* Resource path must match the directory or package structure of
>> > the resource to be retrieved.
>> >* Resource resolution works just like class loading resolution in
>> > terms of which class loader is searched first.
>> >
>> >To access a resource from a JAR file in shared/lib, then, you will want to
>> >make sure you're using the second kind of resource retrieval methods.
>> >After getting the right methods called, the next most common problem is
>> >getting your resource path to match the nested directory structure within
>> >whatever JAR file is holding the resource.
>> >
>> >Craig
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