org.mule.module.launcher.application.CompositeApplicationClassLoader.java Source code

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Here is the source code for org.mule.module.launcher.application.CompositeApplicationClassLoader.java

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/*
 * $Id$
 * --------------------------------------------------------------------------------------
 * Copyright (c) MuleSoft, Inc.  All rights reserved.  http://www.mulesoft.com
 *
 * The software in this package is published under the terms of the CPAL v1.0
 * license, a copy of which has been included with this distribution in the
 * LICENSE.txt file.
 */

package org.mule.module.launcher.application;

import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.net.URL;
import java.util.Arrays;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Defines a classloader that delegates classes and resources resolution to
 * a list of classloaders.
 */
public class CompositeApplicationClassLoader extends ClassLoader implements ApplicationClassLoader, Closeable {

    protected static final Log logger = LogFactory.getLog(CompositeApplicationClassLoader.class);

    private final List<ClassLoader> classLoaders;
    private final String appName;

    public CompositeApplicationClassLoader(String appName, List<ClassLoader> classLoaders) {
        this.appName = appName;
        this.classLoaders = new LinkedList<ClassLoader>(classLoaders);
    }

    @Override
    public String getAppName() {
        return appName;
    }

    @Override
    public Class<?> loadClass(String s) throws ClassNotFoundException {
        for (ClassLoader classLoader : classLoaders) {
            try {
                Class<?> aClass = classLoader.loadClass(s);
                if (logger.isDebugEnabled()) {
                    logger.debug(String.format("Class '%s' loaded from classLoader '%s", s, classLoader));
                }

                return aClass;
            } catch (ClassNotFoundException e) {
                // Ignoring
            }
        }

        throw new ClassNotFoundException(String.format("Cannot load class '%s'", s));
    }

    @Override
    protected synchronized Class<?> loadClass(String s, boolean b) throws ClassNotFoundException {
        for (ClassLoader classLoader : classLoaders) {
            try {
                Class<?> aClass = loadClass(classLoader, s, b);
                if (logger.isDebugEnabled()) {
                    logger.debug(String.format("Class '%s' loaded from classLoader '%s", s, classLoader));
                }

                return aClass;
            } catch (ClassNotFoundException e) {
                // Ignoring
            }
        }

        throw new ClassNotFoundException(String.format("Cannot load class '%s'", s));
    }

    protected Class<?> loadClass(ClassLoader classLoader, String s, boolean b) throws ClassNotFoundException {
        try {
            Method loadClassMethod = findDeclaredMethod(classLoader, "loadClass", String.class, boolean.class);

            return (Class<?>) loadClassMethod.invoke(classLoader, s, b);
        } catch (Exception e) {
            if (logger.isDebugEnabled()) {
                logger.debug(String.format("Error loading class '%s' from classloader '%s'", s, classLoader), e);
            }
        }

        throw new ClassNotFoundException(String.format("Cannot load class '%s'", s));
    }

    @Override
    public URL getResource(String s) {
        for (ClassLoader classLoader : classLoaders) {
            URL resource = classLoader.getResource(s);

            if (resource != null) {
                if (logger.isDebugEnabled()) {
                    logger.debug(String.format("Resource '%s' loaded from classLoader '%s", s, classLoader));
                }

                return resource;
            }
        }

        return null;
    }

    @Override
    public InputStream getResourceAsStream(String s) {
        for (ClassLoader classLoader : classLoaders) {
            InputStream resourceAsStream = classLoader.getResourceAsStream(s);

            if (resourceAsStream != null) {
                if (logger.isDebugEnabled()) {
                    logger.debug(String.format("Stream resource '%s' loaded from classLoader '%s", s, classLoader));
                }

                return resourceAsStream;
            }
        }

        return null;
    }

    @Override
    protected String findLibrary(String s) {
        for (ClassLoader classLoader : classLoaders) {
            String library = findLibrary(s, classLoader);
            if (library != null) {

                if (logger.isDebugEnabled()) {
                    logger.debug(String.format("Library '%s' found in classLoader '%s", s, classLoader));
                }

                return library;
            }
        }

        return null;
    }

    protected String findLibrary(String s, ClassLoader classLoader) {
        try {
            Method findLibraryMethod = findDeclaredMethod(classLoader, "findLibrary", String.class);

            return (String) findLibraryMethod.invoke(classLoader, s);
        } catch (Exception e) {
            if (logger.isDebugEnabled()) {
                logger.debug(String.format("Error finding library '%s' in classloader '%s'", s, classLoader), e);
            }
        }

        return null;
    }

    @Override
    public Enumeration<URL> getResources(String s) throws IOException {
        final Map<String, URL> resources = new HashMap<String, URL>();

        for (ClassLoader classLoader : classLoaders) {
            Enumeration<URL> partialResources = classLoader.getResources(s);

            while (partialResources.hasMoreElements()) {
                URL url = partialResources.nextElement();
                if (resources.get(url.toString()) == null) {
                    resources.put(url.toString(), url);
                }
            }
        }

        return new EnumerationAdapter<URL>(resources.values());
    }

    @Override
    public URL findResource(String s) {
        for (ClassLoader classLoader : classLoaders) {
            URL resource = findResource(classLoader, s);

            if (resource != null) {
                if (logger.isDebugEnabled()) {
                    logger.debug(String.format("Resource '%s' loaded from classLoader '%s", s, classLoader));
                }

                return resource;
            }
        }

        return null;
    }

    @Override
    public void close() {
        for (ClassLoader classLoader : classLoaders) {
            if (classLoader instanceof Closeable) {
                try {
                    ((Closeable) classLoader).close();
                } catch (IOException e) {
                    // Ignore and continue
                }
            }
        }
    }

    private URL findResource(ClassLoader classLoader, String s) {
        try {
            Method findResourceMethod = findDeclaredMethod(classLoader, "findResource", String.class);

            return (URL) findResourceMethod.invoke(classLoader, s);
        } catch (Exception e) {
            if (logger.isDebugEnabled()) {
                logger.debug(String.format("Error finding resource '%s' in classloader '%s'", s, classLoader), e);
            }
        }

        return null;
    }

    private Method findDeclaredMethod(ClassLoader classLoader, String methodName, Class<?>... params)
            throws NoSuchMethodException {
        Class clazz = classLoader.getClass();

        while (clazz != null) {
            try {
                Method findLibraryMethod = clazz.getDeclaredMethod(methodName, params);
                findLibraryMethod.setAccessible(true);

                return findLibraryMethod;
            } catch (NoSuchMethodException e) {
                clazz = clazz.getSuperclass();
            }
        }

        throw new NoSuchMethodException(
                String.format("Cannot find a method '%s' with the given parameter types '%s'", methodName,
                        Arrays.toString(params)));
    }
}