Quadcap Embeddable Database

com/quadcap/io/dir/ClassLoader.java

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package com.quadcap.io.dir;

/* Copyright 1999 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
 *    Redistributions are made at no charge beyond the reasonable cost of
 *    materials and delivery.
 *
 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
 *    years at the cost of materials and delivery.  Such redistributions
 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
 *
 * Redistributions of source code must retain the copyright notices as they
 * appear in each source code file, these license terms, and the
 * disclaimer/limitation of liability set forth as paragraph 6 below.
 *
 * Redistributions in binary form must reproduce this Copyright Notice,
 * these license terms, and the disclaimer/limitation of liability set
 * forth as paragraph 6 below, in the documentation and/or other materials
 * provided with the distribution.
 *
 * The Software is provided on an "AS IS" basis.  No warranty is
 * provided that the Software is free of defects, or fit for a
 * particular purpose.  
 *
 * Limitation of Liability. Quadcap Software shall not be liable
 * for any damages suffered by the Licensee or any third party resulting
 * from use of the Software.
 */

import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Vector;

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.IOException;

import java.net.URL;

import com.quadcap.io.IO;


/**
 * This class implements a JSP class loader
 *
 * @author Stan Bailes
 */
public class ClassLoader extends java.lang.ClassLoader {
    Directory                           root;
    Vector                              jars    = new Vector();

    public ClassLoader(Directory root) {
        super();
        this.root = root;
        try {
            init();
        } catch (IOException ex) {
        }
    }
    

    public Class loadClass(String name) throws ClassNotFoundException {
        return loadClass(name, true);
    }

    // reverse the normal order....
    public synchronized Class loadClass(String name, boolean resolve)
        throws ClassNotFoundException
    {
        // First, check if the class has already been loaded
        Class c = findLoadedClass(name);
        if (c == null) {
            try {
                c = findClass(name);
            } catch (ClassNotFoundException e) {
                c = super.loadClass(name, resolve);
            }
        }
        if (resolve) {
            resolveClass(c);
        }
        return c;
    }

    public Class findClass(String name) throws ClassNotFoundException {
        byte[] b = loadClassData(name);
        return defineClass(name, b, 0, b.length,
                           this.getClass().getProtectionDomain());
    }

    public URL findResource(String name) {
        URL url = null;
        try {
            String fileName = "META-INF" + name;
            for (int i = 0; url == null && i < jars.size(); i++) {
                Directory d = (Directory)jars.elementAt(i);
                url = d.getURL(name);
            }
        } catch (Throwable t) {
            url = null;
        }
        return url;
    }

    private byte[] loadClassData(String name) throws ClassNotFoundException {
        try {
            Entry classFile = locateClassFile(name);
            byte[] b = new byte[(int)(classFile.getSize())];
            InputStream f = classFile.getInputStream();
            IO.readFully(f, b);
            f.close();
            return b;
        } catch (IOException e) {
            throw new ClassNotFoundException("error loading class: " + 
                                             e.toString());
        }
    }

    final Entry locateClassFile(String name) throws ClassNotFoundException {
        String className = name.replace('.', '/') + ".class";
        Entry classFile = null;
        for (int i = 0; classFile == null && i < jars.size(); i++) {
            Directory d = (Directory)jars.elementAt(i);
            classFile = d.getEntry(className);
        }
        if (classFile == null) {
            throw new ClassNotFoundException("not found: " + name);
        }
        return classFile;
    }

    static int tmpCount                 = 0;

    public String getClassPath() {
        StringBuffer sb = new StringBuffer();
        String delim = System.getProperty("path.separator");
        for (int i = 0; i < jars.size(); i++) {
            Directory d = (Directory)jars.elementAt(i);
            if (i > 0) sb.append(delim);
            sb.append(d.getRootPath());
        }
        return sb.toString();
    }
    
    final void init() throws IOException {
        Enumeration e = root.entries();
        Directory classes = null;
        File tmpClasses = null;
        while (e.hasMoreElements()) {
            String path = e.nextElement().toString();
            if (path.endsWith(".jar")) {
                Directory d = null;
                String realPath = root.getRealPath(path);
                if (realPath == null) {
                    throw new IOException("No Path: " + path);
                }
                d = Directory.getDirectory(new File(realPath));
                jars.addElement(d);
            }
        }
    }
}