nioeventreader.java

利用java实现的多人游戏的服务器系统

package com.hypefiend.javagamebook.client;

import com.hypefiend.javagamebook.common.*;

import java.nio.*;
import java.nio.channels.*;
import java.util.*;
import java.net.*;
import java.io.*;

import org.apache.log4j.*;

/**
 * NIOEventReader.java
 *
 * Reads GameEvents from the server.
 * 
 * @author <a href="mailto:[e-mail]">bret barker</a>
 * @version 1.0
 */
public class NIOEventReader extends Thread {
    /** log4j logger */
    private Logger log = Logger.getLogger(NIOEventReader.class);

    /** reference to the game client */
    GameClient gameClient;

    /** connection to server */
    private SocketChannel channel;
    
    /** queue for incoming events */
    private EventQueue queue;

    /** selector to manage server connection */
    private Selector selector;
    
    /** still running? */
    private  boolean running;
 
    /** 
     * constructor.
     */
    public NIOEventReader(GameClient gc, SocketChannel channel, EventQueue queue) {
	super("NIOEventReader");
	this.gameClient = gc;
	this.queue = queue;
	this.channel = channel;
    }

    /** 
     * this is nearly identical to the SelectAndRead.select() method
     */ 
    public void run() {
	try {
	    selector = Selector.open();
	    channel.register(selector, SelectionKey.OP_READ, new Attachment());
	}
	catch (ClosedChannelException cce) {
	    log.error("closedchannelexception while registering channel with selector", cce);
	    return;
	}
	catch (IOException ioe) {
	    log.error("ioexception while registering channel with selector", ioe);
	    return;
	}

	running = true;
	while (running) {
	    try {
		selector.select();
		Set readyKeys = selector.selectedKeys();
		
		Iterator i = readyKeys.iterator();
		while (i.hasNext()) {
		    SelectionKey key = (SelectionKey) i.next();
		    i.remove();
		    
		    SocketChannel channel = (SocketChannel) key.channel();
		    Attachment attachment = (Attachment) key.attachment();

		    try {
			long nbytes = channel.read(attachment.readBuff);
			if (nbytes == -1) {
			    channel.close();
			    
			    GameEvent event = gameClient.createDisconnectEvent("end-of-stream");
			    queue.enQueue(event);
			}
			
			try {
			    if (attachment.readBuff.position() >= attachment.HEADER_SIZE) {
				attachment.readBuff.flip();
				
				while(attachment.eventReady()) {
				GameEvent event = getEvent(attachment);
				queue.enQueue(event);
				attachment.reset();
				}
				attachment.readBuff.compact();
			    }
			}
			catch (IllegalArgumentException e) {
			    log.error("illegalargument while parsing incoming event", e);
			}
		    }
		    catch (IOException ioe) {
			log.warn("IOException during read(), closing channel:" + channel.socket().getInetAddress());
			channel.close();
		    }
		}
	    }
	    catch (IOException ioe2) {
		log.warn("error during select(): " + ioe2.getMessage());
	    }
	    catch (Exception e) {
		log.error("exception during select()", e);
	    }
	}
    }

   private GameEvent getEvent(Attachment attachment) {
	GameEvent event = null;
	ByteBuffer bb = ByteBuffer.wrap(attachment.payload);

	// tell the game client to instantiate the event for us
	event = gameClient.createGameEvent();
	event.read(bb);

	return event;
    }  

    public void shutdown() {
	running = false;
	// force the selector to unblock
	selector.wakeup();
    }
}