Hi Christopher, Pid, Filippo, thanks for your help. I have got this
working as required on my Tomcat server. Here is the code that works.
public class MyCustomClassLoader extends ClassLoader {
public MyCustomClassLoader(ClassLoader contextClassLoader) {
super(contextClassLoader);
}
public synchronized Class<?> arrayToClass(String name, byte[] ct,
boolean resolve) {
Class<?> c = defineClass(name, ct, 0, ct.length);
try {
this.loadClass(c.getName());
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
if (resolve)
System.out.println("Resolving Class in " +
this.getClass());
resolveClass(c);
return c;
}
} // end class
// This is called by...
MyCustomClassLoader cl = new
MyCustomClassLoader(Thread.currentThread().getContextClassLoader());
Class<?> sp = cl.arrayToClass(null, byArray, True);
// use the now loaded class sp for something here
So passing the parent ClassLoader to the constructor was the key.
I'm curious to know what the class
org.apache.catalina.loader.WebappClassLoader is intended for?
I was trying to do...
MyCustomClassLoader extends org.apache.catalina.loader.WebappClassLoader{
and had to add tomcat-catalina-7.0.0.jar to my dependencies in Eclipse.
This works in the IDE but I get the following error when attempting to
deploy the subsequent war in Tomcat (as the jar ended up in the WAR file
too)...
Oct 11, 2011 10:42:30 AM org.apache.tomcat.util.digester.Digester endElement
SEVERE: End event threw exception
java.lang.NoSuchMethodException: org.apache.catalina.deploy.WebXml
addServlet
What is the class WebappClassLoader intended for? It looks like what
Christopher's question is valid :-)
I have a question, though, since the default parent ClassLoader of
any ClassLoader /should/ be the current thread's context ClassLoader,
so none of the above code should be necessary.
but the default ClassLoader used does not appear to be the one of the
Webapp in question.
thanks again,
regards,
Peter
Christopher Schultz wrote:
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1
Pid,
On 10/10/2011 2:23 PM, Pid wrote:
On 10/10/2011 18:51, Peter Lavin wrote:
Hi Filippo, tks for your reply.
I'm not actually specifying any ClassLoader, perhaps I should?
How should I specify a ClassLoader to use when dynamically
loading a class?
You can pass one into the Constructor of your own classloader:
public CustomClassloader(ClassLoader parent) { super(parent); }
And to be perfectly explicit, OP should be doing this when
constructing their CustomClassLoader (presumably in a
ServletContextListener):
CustomClassLoader cl = new
CustomClassLoader(Thread.currentThread().getContextClassLoader());
This should allow Peter's ClassLoader to find superclass definitions
from the webapp's ClassLoader.
I have a question, though, since the default parent ClassLoader of
any ClassLoader /should/ be the current thread's context ClassLoader,
so none of the above code should be necessary.
Perhaps the CustomClassLoader is being initialized in a weird way
that does not make the above connection.
- -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10
(MingW32) Comment: Using GnuPG with Mozilla -
http://enigmail.mozdev.org/
iEYEARECAAYFAk6TWHwACgkQ9CaO5/Lv0PD//gCgthcJU6rJ5pVjkJt3AOgEHqGq
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with best regards,
Peter Lavin,
PhD Candidate,
Computer Architecture & Grid Research Group,
Lloyd Institute, 005,
Trinity College Dublin, Ireland.
+353 1 8961536
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