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PluginClassLoader.java

/*
 * %W% %E%
 *
 * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
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 * Copyright (c) 2003 Sun Microsystems, Inc.  All Rights Reserved.
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistribution of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
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 *   and/or other materails provided with the distribution.
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 * may be used to endorse or promote products derived from this software
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 * This software is provided "AS IS," without a warranty of any kind.
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package net.java.games.input;

import java.io.File;
import java.io.FileFilter;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.StringTokenizer;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

/**
 * Loads all plugins.
 *
 * @version %I% %G%
 * @author Michael Martak
 */
00057 class PluginClassLoader extends ClassLoader {
    
    /**
     * Location of directory to look for plugins
     */
00062     private static String pluginDirectory;
    
    /**
     * File filter for JAR files
     */
00067     private static final FileFilter JAR_FILTER = new JarFileFilter();
    
    /**
     * Create a new class loader for loading plugins
     */
00072     public PluginClassLoader() {
        super(Thread.currentThread().getContextClassLoader());
    }
    
    /**
     * Overrides findClass to first look in the parent class loader,
     * then try loading the class from the plugin file system.
     */
00080     protected Class findClass(String name)
        throws ClassNotFoundException {
        // Try loading the class from the file system.
        byte[] b = loadClassData(name);
        return defineClass(name, b, 0, b.length);
    }
    
    /**
     * Load the class data from the file system
     */
00090     private byte[] loadClassData(String name)
        throws ClassNotFoundException {
        if (pluginDirectory == null) {
            pluginDirectory = DefaultControllerEnvironment.libPath +
                File.separator + "controller";
        }
        try {
            return loadClassFromDirectory(name);
        } catch (Exception e) {
            try {
                return loadClassFromJAR(name);
            } catch (IOException e2) {
                throw new ClassNotFoundException(name, e2);
            }
        }
    }
    
    /**
     * Load the class data from the file system based on parsing
     * the class name (packages).
     */
00111     private byte[] loadClassFromDirectory(String name)
        throws ClassNotFoundException, IOException {
        // Parse the class name into package directories.
        // Look for the class in the plugin directory.
        StringTokenizer tokenizer = new StringTokenizer(name, ".");
        StringBuffer path = new StringBuffer(pluginDirectory);
        while (tokenizer.hasMoreTokens()) {
            path.append(File.separator);
            path.append(tokenizer.nextToken());
        }
        path.append(".class");
        File file = new File(path.toString());
        if (!file.exists()) {
            throw new ClassNotFoundException(name);
        }
        FileInputStream fileInputStream = new FileInputStream(file);
        assert file.length() <= Integer.MAX_VALUE;
        int length = (int)file.length();
        byte[] bytes = new byte[length];
        int length2 = fileInputStream.read(bytes);
        assert length == length2;
        return bytes;
    }
    
    /**
     * Scans through the plugin directory for JAR files and
     * attempts to load the class data from each JAR file.
     */
00139     private byte[] loadClassFromJAR(String name)
        throws ClassNotFoundException, IOException {
        File dir = new File(pluginDirectory);
        File[] jarFiles = dir.listFiles(JAR_FILTER);
        if (jarFiles == null) {
            throw new ClassNotFoundException("Could not find class " + name);
        }
        for (int i = 0; i < jarFiles.length; i++) {
            JarFile jarfile = new JarFile(jarFiles[i]);
            JarEntry jarentry = jarfile.getJarEntry(name + ".class");
            if (jarentry != null) {
                InputStream jarInputStream = jarfile.getInputStream(jarentry);
                assert jarentry.getSize() <= Integer.MAX_VALUE;
                int length = (int)jarentry.getSize();
                assert length >= 0;
                byte[] bytes = new byte[length];
                int length2 = jarInputStream.read(bytes);
                assert length == length2;
                return bytes;
            }
        }
        throw new FileNotFoundException(name);
    }
    
    /**
     * Filters out all non-JAR files, based on whether or not they
     * end in ".JAR" (case-insensitive).
     */
00167     private static class JarFileFilter implements FileFilter {
        public boolean accept(File file) {
            return file.getName().toUpperCase().endsWith(".JAR");
        }
    }
}


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