loadimage.java

用java开发的一个实施策略游戏源码 值得学习一下

/*
	Netwar
	Copyright (C) 2002  Daniel Grund, Kyle Kakligian, Jason Komutrattananon, & Brian Hibler.

	This file is part of Netwar.

	Netwar is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	Netwar is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with Netwar; if not, write to the Free Software
	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

package netwar.utils;

import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Toolkit;
import java.awt.Component;

import java.io.*;

/** A utility class to load images from the JAR file. All images must be located in the /media/ folder.
 * @author Kyle Kakligian
 */
public class LoadImage {
	private static final Component componenet = new Component() {};
	private static final MediaTracker tracker = new MediaTracker(componenet);
	private static int ID = 0;

        /** Constructor.
         */        
	public LoadImage() {
	}

        /** Loads an image and does not return until it is finished loading. (or until an exception)
         * @param filename A string file name reletive to the /media/ directory in the JAR file.
         * @return An Image or null.
         */        
	public static Image LoadWaitForImage(String filename) {
		//Start Daniel's URL hack (to make JARs work)
		//Code based on michael.grimm's contribution to a forum on java.sun.com
		java.net.URL jar[] = new java.net.URL[1];
		jar[0] = null;
		try{jar[0] = ClassLoader.getSystemResource("netwar/media/");}
		catch(Exception e) {}
		java.net.URLClassLoader cl = new java.net.URLClassLoader(jar);
		java.net.URL fileURL = cl.findResource(filename);
		Image ret = Toolkit.getDefaultToolkit().getImage(fileURL);
		//End Daniel's URL hack. Next line is Kyle's original version
		//Image ret = Toolkit.getDefaultToolkit().getImage(filename);

		int id;
		synchronized(componenet) {id = ID++;}
		tracker.addImage(ret, id);

		try { tracker.waitForID(id);}
		catch(InterruptedException ie) {return null;}

		if(tracker.isErrorID(id)) return null;

		return ret;
	}
}