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 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License. You can obtain
 * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
 * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
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package org.glassfish.javaee.full.deployment;

import java.net.URLClassLoader;
import java.net.URL;
import java.util.*;
import java.lang.reflect.Method;
import java.lang.instrument.ClassFileTransformer;
import java.lang.reflect.InvocationTargetException;
import java.io.IOException;
import org.glassfish.api.deployment.InstrumentableClassLoader;
import com.sun.enterprise.loader.EJBClassLoader;

/**
 * Simplistic class loader which will delegate to each module class loader in the order
 * they were added to the instance
 *
 * @author Jerome Dochez
 */
public class EarClassLoader extends URLClassLoader implements InstrumentableClassLoader {

    private final List delegates = new LinkedList();
    private final Method findClass;
    private final Method findLoadedClass;
    private final Method findResource;
    private final Method findResources;
    private final static String EAR_LIB_MODULE = " __ear_lib_module";

    public EarClassLoader(URL[] urls, ClassLoader classLoader) {
        super(new URL[0], classLoader); 

        // the classloader to load library jars at ear level
        EJBClassLoader earLibClassLoader = new EJBClassLoader(this);
        for (URL url : urls) {
            earLibClassLoader.addURL(url);
        }
        addModuleClassLoader(EAR_LIB_MODULE, earLibClassLoader);

        try {
            findClass = ClassLoader.class.getDeclaredMethod("findClass", new Class[] {String.class});
            findClass.setAccessible(true);

            findLoadedClass = ClassLoader.class.getDeclaredMethod("findLoadedClass", new Class[] {String.class});
            findLoadedClass.setAccessible(true);


            findResource = ClassLoader.class.getDeclaredMethod("findResource", new Class[] {String.class});
            findResource.setAccessible(true);

            findResources = ClassLoader.class.getDeclaredMethod("findResources", new Class[] {String.class});
            findResources.setAccessible(true);
            
        } catch(NoSuchMethodException e) {
            // this is impossible.
            throw new RuntimeException(e);
        }
    }

    public void addModuleClassLoader(String moduleName, ClassLoader cl) {
        delegates.add(new ClassLoaderHolder(moduleName, cl));
    }

    public ClassLoader getModuleClassLoader(String moduleName) {
        for (ClassLoaderHolder clh : delegates) {
            if (moduleName.equals(clh.moduleName)) {
                return clh.loader;
            }
        }
        return null;
    }

    public ClassLoader copy() {
        ClassLoader cLoader = getModuleClassLoader(EAR_LIB_MODULE);
        if (cLoader instanceof InstrumentableClassLoader) {
            return ((InstrumentableClassLoader)getModuleClassLoader(
                EAR_LIB_MODULE)).copy();
        }
        return null;
    }

    public synchronized void addTransformer(ClassFileTransformer transformer) {
        ClassLoader cLoader = getModuleClassLoader(EAR_LIB_MODULE);
        if (cLoader instanceof InstrumentableClassLoader) {
            ((InstrumentableClassLoader)getModuleClassLoader(
                EAR_LIB_MODULE)).addTransformer(transformer);
        }
    }

    @Override
    protected Class findClass(String s) throws ClassNotFoundException {
        
        for (ClassLoaderHolder clh : delegates) {
            try {
                Class clazz = (Class) findLoadedClass.invoke(clh.loader, s);
                if (clazz!=null) {
                    return clazz;
                }
            } catch (IllegalAccessException e) {
            } catch (InvocationTargetException e) {
            }
        }
        
        try {
            return super.findClass(s);
        } catch(ClassNotFoundException e) {
                // ignore
        }

        for (ClassLoaderHolder clh : delegates) {
            try {
                Class clazz = (Class) findClass.invoke(clh.loader, s);
                if (clazz!=null) {
                    return clazz;
                }
            } catch(IllegalAccessException e) {
                
            } catch(InvocationTargetException e) {
                // not found most likely.   
            }
        }
        throw new ClassNotFoundException(s);
    }

    private class ClassLoaderHolder {
        final ClassLoader loader;
        final String moduleName;

        private ClassLoaderHolder(String moduleName, ClassLoader loader) {
            this.loader = loader;
            this.moduleName = moduleName;
        }
    }

    @Override
    public URL findResource(String s) {
        URL url = null;
        url = super.findResource(s);
        if (url!=null) {
            return url;
        }
        for(ClassLoaderHolder clh : delegates) {
            try {
                url = (URL) findResource.invoke(clh.loader, s);
            } catch (IllegalAccessException e) {

            } catch (InvocationTargetException e) {

            }
            if (url!=null) {
                return url;
            }
        }
        return null;
    }

    @Override
    public Enumeration findResources(String s) throws IOException {
        Enumeration result = super.findResources(s);
        if (result!=null) {
            return result;
        }
        Vector urls = new Vector();
        for(ClassLoaderHolder clh : delegates) {
            try {
                Enumeration enumeration = (Enumeration) findResources.invoke(clh.loader, s);
                while (enumeration.hasMoreElements()) {
                    urls.add(enumeration.nextElement());
                }
            } catch (IllegalAccessException e) {

            } catch (InvocationTargetException e) {

            }
        }
        return urls.elements();
    }
}