UnsatisfiedLinkError using Java Webstart with custom classloader

From:
Andi <andreas.schneider@skillworks.de>
Newsgroups:
comp.lang.java.programmer
Date:
Mon, 17 Mar 2008 03:42:42 -0700 (PDT)
Message-ID:
<0b8043f7-58f0-47b9-8c4f-0a3ae970df88@n58g2000hsf.googlegroups.com>
Hi,

I have a big problem to get my Application running on java webstart. I
have a custom classloader which will be used for some classes. Also I
need to load a dll which will be used by a native interface.

Here is my application entry point:

public class ApplicationStarter
{
    public static void main(String[] args)
    {
        try
        {
            System.setSecurityManager(null);
            CustomClassLoader classLoader = new
CustomClassLoader(Thread.currentThread().getContextClassLoader());
            Thread.currentThread().setContextClassLoader(classLoader);
 
classLoader.loadClass("bugreport.jws6.Application").getMethod("main",
new Class[] { String[].class })
                    .invoke(null, new Object[] { args });
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }
}

That all the classloading my classloader will be used I am calling the
real applcation per reflection loaded by my classloader.

Here the application I start:

public class Application
{
    public static void main(String[] args)
    {
        try
        {
            System.loadLibrary("jws6-bugreport");
            NativeInterface nativeInterface = new NativeInterface();
            System.out.println("Native call result :" +
nativeInterface.doSomething());
        }
        catch (Throwable t)
        {
            t.printStackTrace();
        }
    }
}

Here my Classloader:

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;

public class CustomClassLoader extends ClassLoader
{

    private HashMap<String, Class<?>> loadedClasses = new
HashMap<String, Class<?>>();

    public CustomClassLoader(ClassLoader parent)
    {
        super(parent);
    }

    public Class<?> customLoadClass(String name) throws
ClassNotFoundException
    {
        System.out.println("Custom loading of class " + name);
        Class<?> clazz = this.loadedClasses.get(name);
        if(clazz == null)
        {
            try
            {
                String classFilename = name.replace('.', '/') +
".class";

                InputStream inputStream =
getResourceAsStream(classFilename);
                if(inputStream == null)
                    throw new ClassNotFoundException(name);

                ByteArrayOutputStream baout = new
ByteArrayOutputStream();
                byte[] b = new byte[2048];
                int byteCount;
                while((byteCount = inputStream.read(b, 0, 2048)) !=
-1)
                {
                    baout.write(b, 0, byteCount);
                }
                byte[] buffer = baout.toByteArray();
                baout.close();

                clazz = defineClass(name, buffer, 0, buffer.length);
                this.loadedClasses.put(name, clazz);

            }
            catch (IOException e)
            {
                throw new ClassNotFoundException(name, e);
            }
        }

        return clazz;
    }

    @Override
    public Class<?> loadClass(String name) throws
ClassNotFoundException
    {
        Class<?> clazz;
        if(name.startsWith("bugreport.jws6"))
        {
            clazz = customLoadClass(name);
        }
        else
        {
            clazz = super.loadClass(name);
        }
        return clazz;
    }

    public String toString()
    {
        return getClass().getName();
    }
}

That works perfect when I have a normal client application but it
doesn't when I use Java Webstart.

Here my jnlp:

<?xml version="1.0" encoding="utf-8"?>
<!-- JNLP File for SwingSet2 Demo Application -->
<jnlp
  spec="1.0+"
  codebase="http://localhost/jws6-bugreport"
  href="Webstart6Bugreport.jnlp">
  <information>
    <title>Webstart 6 Bugreport</title>
    <vendor>Skillworks AG</vendor>
    <description>None</description>
    <description kind="short">None</description>
    <offline-allowed/>
  </information>
  <security>
      <all-permissions/>
  </security>
  <resources>
    <j2se version="1.5"/>
    <nativelib href="jws6-bugreport-native.jar"/>

<jar href="jws6-bugreport-app-1.0.jar" main="true"/>
<jar href="jws6-bugreport-jni-1.0.jar"/>

  </resources>
  <application-desc main-class="bugreport.jws6.ApplicationStarter"/>
</jnlp>

Here the native code:

public class NativeInterface {

    public native String doSomething();
}

#include "NativeInterface.h"

JNIEXPORT jstring JNICALL
Java_bugreport_jws6_NativeInterface_doSomething
  (JNIEnv *jEnv, jobject obj)
{

    jstring referenceKey = jEnv->NewStringUTF("Native Call done");
    return referenceKey;
}

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class bugreport_jws6_NativeInterface */

#ifndef _Included_bugreport_jws6_NativeInterface
#define _Included_bugreport_jws6_NativeInterface
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class: bugreport_jws6_NativeInterface
 * Method: doSomething
 * Signature: ()Ljava/lang/String;
 */
JNIEXPORT jstring JNICALL
Java_bugreport_jws6_NativeInterface_doSomething
  (JNIEnv *, jobject);

#ifdef __cplusplus
}
#endif
#endif

Does anybody help me with that problem...?
Thanks for every hint

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