Because you got NoClassDefFoundError instead of ClassNotFoundException, it
is *not* ProsumerTestTag that is the missing one. Instead, check the
sources of ProsumerTag for references to *other* classes, and make sure
all of *those* classes are also available in your web app.
Craig McClanahan
On Tue, 11 Sep 2001, Guy Verbist wrote:
> Date: Tue, 11 Sep 2001 12:04:06 +0100
> From: Guy Verbist <[EMAIL PROTECTED]>
> Reply-To: [EMAIL PROTECTED]
> To: "'[EMAIL PROTECTED]'" <[EMAIL PROTECTED]>
> Subject: Problem with loading classes dynamically,
> new objects can't "see" things in webapp.
>
> Hi all.
>
> I hope I'm not being too dumb here.
>
> My servlet code wants to load classes dynamically at runtime. Instances of
> these classes will call back into the servlet code.
>
> So, my server.xml looks like this:
>
> <Context path="/prosumer"
> docBase="c:\Products\suite\current\peng\webapp"
>
> with all the class files under ...\webapp\WEB-INF\classes
>
> Mostly it works fine.
> However when I try to execute this line:
>
> Class c = Class.forName("com.psl.test.customtags.ProsumerTestTag");
>
> where ProsumerTestTag is defined thusly:
>
> public class ProsumerTestTag implements CustomTag {
>
> tomcat keels over with:
>
> java.lang.NoClassDefFoundError: com/psl/customtags/CustomTag
> at java.lang.ClassLoader.defineClass0(Native Method)
> at java.lang.ClassLoader.defineClass(ClassLoader.java:486)
> at
> java.security.SecureClassLoader.defineClass(SecureClassLoader.java:111)
> at java.net.URLClassLoader.defineClass(URLClassLoader.java:248)
> at java.net.URLClassLoader.access$100(URLClassLoader.java:56)
> at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
> at java.security.AccessController.doPrivileged(Native Method)
> at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:297)
> at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:286)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:253)
> at
> org.apache.tomcat.loader.AdaptiveClassLoader.loadClass(AdaptiveClassLoader.j
> ava:446)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:253)
> at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:313)
> at java.lang.Class.forName0(Native Method)
> at java.lang.Class.forName(Class.java:120)
>
> left in the jvm.stderr
>
> I guess it can't find the "CustomTag" that ProsumerTestTag implements.
> However com/psl/customtags/CustomTag *realy is* in the webapp.
>
> I'm running tomcat 3.2.2 as a service on a Win2k server box, and if I add
> the whole of the webapp code to the classpath for the jvm for tomcat by
> editing the ...wrapper.properties for jk_nt_service.exe, then the whole
> thing works. However this workaround seems to be suboptimal.
>
> My question is why can't a class loaded by Class.forName() see things in
> webapp/WEB-INF/classes, only things in the regular JVM classpath, when the
> rest of the webapp can see things in the webapp/WEB-INF/classes?
>
> I guess my call to Class.forName() is creating a different context for the
> new class to what is created for the rest of the servlet, but is there some
> way I can resolve the differences?
>
> Thanks very much.
>
> Guy
>
