com.netspective.commons.lang.ResourceLoader.java Source code

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Here is the source code for com.netspective.commons.lang.ResourceLoader.java

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/*
 * Copyright (c) 2000-2004 Netspective Communications LLC. All rights reserved.
 *
 * Netspective Communications LLC ("Netspective") permits redistribution, modification and use of this file in source
 * and binary form ("The Software") under the Netspective Source License ("NSL" or "The License"). The following
 * conditions are provided as a summary of the NSL but the NSL remains the canonical license and must be accepted
 * before using The Software. Any use of The Software indicates agreement with the NSL.
 *
 * 1. Each copy or derived work of The Software must preserve the copyright notice and this notice unmodified.
 *
 * 2. Redistribution of The Software is allowed in object code form only (as Java .class files or a .jar file
 *    containing the .class files) and only as part of an application that uses The Software as part of its primary
 *    functionality. No distribution of the package is allowed as part of a software development kit, other library,
 *    or development tool without written consent of Netspective. Any modified form of The Software is bound by these
 *    same restrictions.
 *
 * 3. Redistributions of The Software in any form must include an unmodified copy of The License, normally in a plain
 *    ASCII text file unless otherwise agreed to, in writing, by Netspective.
 *
 * 4. The names "Netspective", "Axiom", "Commons", "Junxion", and "Sparx" are trademarks of Netspective and may not be
 *    used to endorse or appear in products derived from The Software without written consent of Netspective.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" WITHOUT A WARRANTY OF ANY KIND. ALL EXPRESS OR IMPLIED REPRESENTATIONS AND
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT,
 * ARE HEREBY DISCLAIMED.
 *
 * NETSPECTIVE AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE OR ANY THIRD PARTY AS A
 * RESULT OF USING OR DISTRIBUTING THE SOFTWARE. IN NO EVENT WILL NETSPECTIVE OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
 * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THE SOFTWARE, EVEN
 * IF IT HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 */
package com.netspective.commons.lang;

import java.net.URL;

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

public class ResourceLoader {
    private static final Log log = LogFactory.getLog(ResourceLoader.class);

    /**
     * This method will search for <code>resource</code> in different
     * places. The search order is as follows:
     * <p/>
     * <ol>
     * <li>Search for <code>resource</code> using the thread context
     * class loader. If that fails, search for <code>resource</code> using
     * the class loader that loaded this class.
     * <li>Try one last time with <code>ClassLoader.getSystemResource(resource)</code>.
     * </ol>
     */
    public static URL getResource(String resource) {
        ClassLoader classLoader = null;
        URL url = null;

        try {
            classLoader = Thread.currentThread().getContextClassLoader();
            if (classLoader != null) {
                url = classLoader.getResource(resource);
                if (url != null)
                    return url;
            }

            // We could not find resource. Lets try with the classloader that loaded this class.
            classLoader = ResourceLoader.class.getClassLoader();
            if (classLoader != null) {
                url = classLoader.getResource(resource);
                if (url != null)
                    return url;
            }
        } catch (Throwable t) {
            log.warn("Caught Exception while in ResourceLoader.getResource.", 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.
        return ClassLoader.getSystemResource(resource);
    }

    /**
     * Find the first resource in the list and return the URL to it.
     *
     * @param resources The list of different resource names to try
     *
     * @return The URL for the first resource found or NULL if resource could not be located
     */
    public static URL getFirstResource(String[] resources) {
        for (int i = 0; i < resources.length; i++) {
            String resource = resources[i];
            URL result = getResource(resource);
            if (result != null)
                return result;
        }

        return null;
    }
}