/* * ModuleLoader - A generic, policy-driven class loader. * Copyright (c) 2004, Richard S. Hall * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * *   * Redistributions of source code must retain the above copyright *     notice, this list of conditions and the following disclaimer. *   * Redistributions in binary form must reproduce the above copyright *     notice, this list of conditions and the following disclaimer in *     the documentation and/or other materials provided with the *     distribution. *   * Neither the name of the ungoverned.org nor the names of its *     contributors may be used to endorse or promote products derived *     from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * Contact: Richard S. Hall (heavy@ungoverned.org) * Contributor(s): ***/package org.ungoverned.moduleloader.search;import java.net.URL;import org.ungoverned.moduleloader.Module;import org.ungoverned.moduleloader.ModuleManager;import org.ungoverned.moduleloader.SearchPolicy;/** * <p> * This class implements a <tt>ModuleLoader</tt> search policy that * exhaustively and linearly searches all modules when trying to load * a particular class or resource. As a result of this algorithm, every class loader * for every module is essentially identical, meaning that each will * load a given class or resource from the same class loader. This search policy * provides behavior similar to the standard <tt>CLASSPATH</tt> environment * variable approach. The main difference is that modules can be added * to the module manager at run time; thus, the class path is dynamically * extended. This search policy is not fully dynamic, since it does not * support the removal of modules at run time; if a module is removed from * the module manager at run time, there is no attempt to clean up its * loaded classes. * </p> * @see org.ungoverned.moduleloader.SearchPolicy * @see org.ungoverned.moduleloader.Module * @see org.ungoverned.moduleloader.ModuleClassLoader * @see org.ungoverned.moduleloader.ModuleManager**/public class ExhaustiveSearchPolicy implements SearchPolicy{    private ModuleManager m_mgr = null;    /**     * This method is part of the <tt>SearchPolicy</tt> interface.     * This method is called by the <tt>ModuleManager</tt> once to     * give the search policy instance a reference to its associated     * module manager. This method should be implemented such that     * it cannot be called twice; calling this method a second time     * should produce an illegal state exception.     * @param mgr the module manager associated with this search policy.     * @throws java.lang.IllegalStateException if the method is called     *         more than once.    **/    public void setModuleManager(ModuleManager mgr)        throws IllegalStateException    {        if (m_mgr == null)        {            m_mgr = mgr;        }        else        {            throw new IllegalStateException("Module manager is already initialized");        }    }    /**     * This method finds the specified class for the specified module. It     * finds the class by linearly asking each module in the module manager     * for the specific class. As soon as the class is found, it is returned.     * @param module the target module that is loading the class.     * @param name the name of the class being loaded.     * @return the class if found, <tt>null</tt> otherwise.    **/    public Class findClass(Module module, String name)    {        Module[] modules = m_mgr.getModules();        for (int i = 0; i < modules.length; i++)        {            try {                Class clazz = modules[i].getClassLoader().searchForClass(name);                if (clazz != null)                {                    return clazz;                }            } catch (Throwable th) {            }        }        return null;    }    /**     * This method finds the specified resource for the specified module. It     * finds the resource by linearly asking each module in the module manager     * for specific resource. As soon as the resource is found, a <tt>URL</tt>     * to it is returned.     * @param module the target module that is loading the resource.     * @param name the name of the resource being loaded.     * @return a <tt>URL</tt> to the resource if found, <tt>null</tt> otherwise.    **/    public URL findResource(Module module, String name)    {        Module[] modules = m_mgr.getModules();        for (int i = 0; i < modules.length; i++)        {            try {                URL url = modules[i].getClassLoader().searchForResource(name);                if (url != null)                {                    return url;                }            } catch (Throwable th) {            }        }        return null;    }}