refjxtaloader.java

jxme的一些相关程序,主要是手机上程序开发以及手机和计算机通信的一些程序资料,程序编译需要Ant支持

/*
 * Copyright (c) 2001 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:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *       Sun Microsystems, Inc. for Project JXTA."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact Project JXTA at http://www.jxta.org.
 *
 * 5. Products derived from this software may not be called "JXTA",
 *    nor may "JXTA" appear in their name, without prior written
 *    permission of Sun.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 SUN MICROSYSTEMS OR
 * ITS 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Project JXTA.  For more
 * information on Project JXTA, please see
 * <http://www.jxta.org/>.
 *
 * This license is based on the BSD license adopted by the Apache Foundation.
 *
 * $Id: RefJxtaLoader.java,v 1.5 2002/04/05 00:08:38 hamada Exp $
 */

package net.jxta.impl.loader;

import java.io.*;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Hashtable;
import net.jxta.platform.JxtaLoader;

/*
 * This class is the reference implementation of the JxtaLoader.
 */
public class RefJxtaLoader extends JxtaLoader {

  private String dir;
  private Hashtable Classes = new Hashtable();

  public RefJxtaLoader(String dir) {
    this( dir, RefJxtaLoader.class.getClassLoader() );
  }

  public RefJxtaLoader(String dir, ClassLoader loader) {
    super( loader );
    this.dir = dir;
  }
    // Make a stub for a version that uses URL, so that code that load
    // services can be written properly, even if it works only for classes
    // that do not need download.
  public Class loadClass(String name, String url, boolean resolve)
	  throws ClassNotFoundException {
    try {
        return loadClass(name, resolve);
    } catch (ClassNotFoundException e) {
		  if (url != null && url.length() > 0) try {
			  Class clazz = URLClassLoader.newInstance(new URL[]{new URL(url)}).loadClass(name);
			  if (resolve) resolveClass(clazz);
			  return clazz;
		  } catch (MalformedURLException ex) {
			  throw new ClassNotFoundException("Malformed URL \"" + url + "\"");
		  }
        throw new ClassNotFoundException(name);
    }
    }

  public Class loadClass(String name, boolean resolve)
     throws ClassNotFoundException
    {
      try {
        // first try the cache, then the parent class loader, then the system class loader
        Class newClass = (Class)Classes.get(name);
        if (newClass == null ) { // I'd rather say parent.loadClass() but it is private
          try {
            newClass = super.loadClass(name, false);
            if (newClass != null)
              return newClass;
          } catch (ClassNotFoundException e) {
          }
        }
        if (newClass == null) {
          try {
            newClass = findSystemClass(name);
            if (newClass != null)
              return newClass;
          } catch (ClassNotFoundException e) {
          }
	  
	  // We need to also check if the Context ClassLoader associated to the
	  // the current thread can load the class.
	  if (newClass == null) {
	      try {
		  newClass = Thread.currentThread().getContextClassLoader().loadClass (name);
		  if (newClass != null) {
		      return newClass;
		  }
	      } catch (ClassNotFoundException ez1) {
	      }
	  }

          byte[] buf = bytesForClass(name);
          newClass = defineClass(name, buf, 0, buf.length);
          Classes.put(name, newClass);
        }
        if (resolve)
          resolveClass(newClass);
        return newClass;
      } catch (IOException e) {
        throw new ClassNotFoundException(e.toString());
      }
    }

  /**
   * load a class file from the load class directory
   */

  protected byte[] bytesForClass(String name)
    throws IOException, ClassNotFoundException {

      File file = new File(dir + name.replace('.', File.separatorChar) + ".java");
      FileInputStream in = new FileInputStream(file);
      int length = (int) file.length();
      if (length == 0)
        throw new ClassNotFoundException(name);
      byte[] buf = new byte[length];
      in.read(buf);
      return buf;
  }
}