Loader.java

//
//  ========================================================================
//  Copyright (c) 1995-2017 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.util;

import java.net.URL;
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.ResourceBundle;

/* ------------------------------------------------------------ */
/** ClassLoader Helper.
 * This helper class allows classes to be loaded either from the
 * Thread's ContextClassLoader, the classloader of the derived class
 * or the system ClassLoader.
 *
 * <B>Usage:</B><PRE>
 * public class MyClass {
 *     void myMethod() {
 *          ...
 *          Class c=Loader.loadClass(this.getClass(),classname);
 *          ...
 *     }
 * </PRE>          
 * 
 */
public class Loader
{
    /* ------------------------------------------------------------ */
    public static URL getResource(String name)
    {
        ClassLoader loader=Thread.currentThread().getContextClassLoader();
        return loader==null?ClassLoader.getSystemResource(name):loader.getResource(name); 
    }

    /* ------------------------------------------------------------ */
    /** Load a class.
     * <p>Load a class either from the thread context classloader or if none, the system
     * loader</p>
     * 
     * @param name the name of the new class to load
     * @return Class
     * @throws ClassNotFoundException if not able to find the class
     */
    @SuppressWarnings("rawtypes")
    public static Class loadClass(String name)
        throws ClassNotFoundException
    {
        ClassLoader loader=Thread.currentThread().getContextClassLoader();
        return (loader==null ) ? Class.forName(name) : loader.loadClass(name);
    } 

    /* ------------------------------------------------------------ */
    /** Load a class.
     * Load a class from the same classloader as the passed  <code>loadClass</code>, or if none
     * then use {@link #loadClass(String)}
     * 
     * @param loaderClass a similar class, belong in the same classloader of the desired class to load
     * @param name the name of the new class to load
     * @return Class
     * @throws ClassNotFoundException if not able to find the class
     */
    @SuppressWarnings("rawtypes")
    public static Class loadClass(Class loaderClass, String name)
        throws ClassNotFoundException
    {
        if (loaderClass!=null && loaderClass.getClassLoader()!=null)
            return loaderClass.getClassLoader().loadClass(name);
        return loadClass(name);
    }
    
    /* ------------------------------------------------------------ */
    public static ResourceBundle getResourceBundle(String name,boolean checkParents,Locale locale)
        throws MissingResourceException
    {
        ClassLoader loader=Thread.currentThread().getContextClassLoader();
        return loader==null ? ResourceBundle.getBundle(name, locale) : ResourceBundle.getBundle(name, locale, loader);
    }
}