哪位大哥给一下书中UDPClient类的实现代码？

在这里：

package com.jdon.jserver.connector.udp;

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

import com.jdon.util.Debug;

import com.jdon.jserver.connector.SocketDataHandler;
import com.jdon.jserver.connector.queue.QueueFactory;

public class UDPClient extends Thread {
private final static String module = UDPClient.class.getName();

private SocketDataHandler socketDataHandler;

private Selector selector;
private InetSocketAddress socketAddress ;
private DatagramChannel channel;

public UDPClient() {
try {
socketDataHandler = new SocketDataHandler(QueueFactory.UDP_QUEUE);
selector = Selector.open();
} catch (Exception e) {
Debug.logError("init error:" + e, module);
}
}

public void openDatagramChannel(String url, int port) {
if (channel != null) return ;
try {
channel = DatagramChannel.open();
channel.configureBlocking(false);

socketAddress = new InetSocketAddress(url, port);
channel.connect(socketAddress); //绑定socketAddress
//向selector注册该channel
SelectionKey key = channel.register(selector,
SelectionKey.OP_READ |
SelectionKey.OP_WRITE);

Debug.logVerbose("connected the Server:"+url+":"+port, module);

} catch (Exception e) {
Debug.logError(e, module);
}
}

public void run() {
try {
while (!Thread.interrupted()) {
if (selector.select(30) > 0) {
doSelector(selector);
}
}
} catch (Exception e) {
Debug.logError("run error:" + e, module);
close(channel);
}
}

private void doSelector(Selector selector) throws Exception {
Set readyKeys = selector.selectedKeys();
Iterator readyItor = readyKeys.iterator();
while (readyItor.hasNext()) {
SelectionKey key = (SelectionKey) readyItor.next();
readyItor.remove();

doKey(key);
readyKeys.clear();
}
}

private void doKey(SelectionKey key) {
DatagramChannel keyChannel = null;
try {
keyChannel = (DatagramChannel) key.channel();
if (key.isReadable()) { //如果可以从服务器读取response数据

byte[] array = socketDataHandler.getByte();
ByteBuffer buffer = ByteBuffer.wrap(array);
keyChannel.receive(buffer);

socketDataHandler.receiveResponse(array);

key.interestOps(SelectionKey.OP_WRITE);
selector.wakeup();
} else if (key.isWritable()) { //如果可以向服务器发送request数据

byte[] request = socketDataHandler.sendRequest();
ByteBuffer buffer = ByteBuffer.wrap(request);
keyChannel.write(buffer);

key.interestOps(SelectionKey.OP_READ);
selector.wakeup();
}
} catch (Exception e) {
Debug.logError("run error:" + e, module);
}
}

public void close(DatagramChannel datagramChannel) {
if (datagramChannel != null) {
try {
datagramChannel.disconnect();
datagramChannel.close();
SelectionKey key = datagramChannel.keyFor(selector);
key.cancel();
datagramChannel = null;
} catch (Exception ignored) {
}
}
}

}