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Puts together an ActiveMQ OSGi bundle
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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.log4j.helpers;

import java.net.URL;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;
import java.io.InterruptedIOException;

/**
 * Load resources (or images) from various sources.
 *
 * @author Ceki Gülcü
 */

public class Loader {

    static final String TSTR = "Caught Exception while in Loader.getResource. This may be innocuous.";

    static private boolean ignoreTCL = false;

    static {
        String ignoreTCLProp = OptionConverter.getSystemProperty("log4j.ignoreTCL", null);
        if (ignoreTCLProp != null) {
            ignoreTCL = OptionConverter.toBoolean(ignoreTCLProp, true);
        }
    }

    /**
     * Get a resource by delegating to getResource(String).
     *
     * @param resource resource name
     * @param clazz    class, ignored.
     * @return URL to resource or null.
     * @deprecated as of 1.2.
     */
    public static URL getResource(String resource, Class clazz) {
        return getResource(resource);
    }

    /**
     * This method will search for resource in different places. The search order is as follows:
     * 
     *
     * Search for resource using the class
     * loader that loaded this class (Loader).

     * 
     * Try one last time with
     * ClassLoader.getSystemResource(resource), that is is using the
     * system class loader.
     * 
     *
     *  Nota bene: In versions of reload4j 1.2.23 and earlier, the jaadoc documentation stated that
     *  the thread context class loader was used but when running under JDK 9 and later this
     *  was not actually the case. As of version 1.2.24, the javadoc above matches the code as executed.
     *  
     *
     *
     * @param resource the resource to load
     */
    static public URL getResource(String resource) {
        ClassLoader classLoader = null;
        URL url = null;

        try {
            // We could not find resource. Ler us now try with the
            // classloader that loaded this class.
            classLoader = Loader.class.getClassLoader();
            if (classLoader != null) {
                LogLog.debug("Trying to find [" + resource + "] using " + classLoader + " class loader.");
                url = classLoader.getResource(resource);
                if (url != null) {
                    return url;
                }
            }
        } catch (SecurityException t) {
            // can't be InterruptedException or InterruptedIOException
            // since not declared, must be error or RuntimeError.
            LogLog.warn(TSTR, t);
        }

        // Last ditch attempt: get the resource from the class path. It
        // may be the case that clazz was loaded by the Extentsion class
        // loader which the parent of the system class loader. Hence the
        // code below.
        LogLog.debug("Trying to find [" + resource + "] using ClassLoader.getSystemResource().");
        return ClassLoader.getSystemResource(resource);
    }

    /**
     * Are we running under JDK 1.x?
     * @deprecated with no replacement
     */
    @Deprecated
    public static boolean isJava1() {
        return false;
    }

    /**
     * Get the Thread Context Loader which is a JDK 1.2 feature. If we are running under JDK 1.1 or anything else goes
     * wrong the method returns
     * null.
     */
    private static ClassLoader getTCL() throws IllegalAccessException, InvocationTargetException {

        // Are we running on a JDK 1.2 or later system?
        Method method = null;
        try {
            method = Thread.class.getMethod("getContextClassLoader", null);
        } catch (NoSuchMethodException e) {
            // We are running on JDK 1.1
            return null;
        }

        return (ClassLoader) method.invoke(Thread.currentThread(), null);
    }

    /**
     * Load the specified class using the {@linl Class#forName} method.
     *
     * Nota bene: In versions of reload4j 1.2.23 and earlier, the documentation stated that
     * the thread context class loader was used to load the specified class but
     * when running under JDK 9 and later this was not actually the case. As of version 1.2.24,
     * the javadoc above matches the code as executed.
     * 
     *
     * @param clazz the name of class to load
     */
    static public Class loadClass(String clazz) throws ClassNotFoundException {
        return Class.forName(clazz);
    }
}