Netty权威指南-NIO实现TimeClient客户端源代码

package com.jianweigang.NIO;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

public class TimeClient {
private static int DEFAULT_PORT = 8080;
public static void main(String[] args) throws IOException {
int port = 8080;
if(args != null && args.length > 0 ) {
try {
port = Integer.valueOf(args[0]);
}catch(NumberFormatException e){
//如果没有传，那我们就使用默认的端口
port = DEFAULT_PORT;
}
}
//单独启动一个线程
new Thread(new TimeClientHandle("127.0.0.1", port), "TimeClient-001").start();
}
}

class TimeClientHandle implements Runnable{
private String host;
private int port;
private Selector selector;
private SocketChannel socketChannel;
private volatile boolean stop;

public TimeClientHandle(String host, int port) {
this.host = host == null ? "127.0.0.1" : host;
this.port = port;
try {
selector = Selector.open();
socketChannel = SocketChannel.open();
socketChannel.configureBlocking(false);
//          socketChannel.register(selector, SelectionKey.OP_READ);
} catch (IOException e) {
e.printStackTrace();
System.exit(1);
}
}

public void run() {
// TODO Auto-generated method stub
try {
doConnect();
} catch (IOException e) {
e.printStackTrace();
System.exit(1);
}
while(!stop) {
try {
selector.select(1000);
Set<SelectionKey> selectedKeys = selector.selectedKeys();
Iterator<SelectionKey> it = selectedKeys.iterator();
SelectionKey key = null;
while(it.hasNext()) {
key = it.next();
it.remove();
try {
handleInput(key);
}catch(Exception e) {
if (key != null) {
key.cancel();
if (key.channel() != null)
key.channel().close();
}
}
}
}catch(Exception e){

}
}
// 多路复用器关闭后，所有注册在上面的Channel和Pipe等资源都会被自动去注册并关闭，所以不需要重复释放资源
if (selector != null)
try {
selector.close();
} catch (IOException e) {
e.printStackTrace();
}
}

private void handleInput(SelectionKey key) throws IOException {
if (key.isValid()) {
// 判断是否连接成功
SocketChannel sc = (SocketChannel) key.channel();
if (key.isConnectable()) {
if (sc.finishConnect()) {
sc.register(selector, SelectionKey.OP_READ);
doWrite(sc);
} else
System.exit(1);// 连接失败，进程退出
}
if (key.isReadable()) {
ByteBuffer readBuffer = ByteBuffer.allocate(1024);
int readBytes = sc.read(readBuffer);
if (readBytes > 0) {
readBuffer.flip();
byte[] bytes = new byte[readBuffer.remaining()];
readBuffer.get(bytes);
String body = new String(bytes, "UTF-8");
System.out.println("Now is : " + body);
this.stop = true;
} else if (readBytes < 0) {
// 对端链路关闭
key.cancel();
sc.close();
} else
; // 读到0字节，忽略
}
}
}
private void doConnect() throws IOException {
// 如果直接连接成功，则注册到多路复用器上，发送请求消息，读应答
if (socketChannel.connect(new InetSocketAddress(host, port))) {
socketChannel.register(selector, SelectionKey.OP_READ);
doWrite(socketChannel);
} else
socketChannel.register(selector, SelectionKey.OP_CONNECT);
}

private void doWrite(SocketChannel sc) throws IOException {
byte[] req = "QUERY TIME ORDER".getBytes();
ByteBuffer writeBuffer = ByteBuffer.allocate(req.length);
writeBuffer.put(req);
writeBuffer.flip();
sc.write(writeBuffer);
if (!writeBuffer.hasRemaining())
System.out.println("Send order 2 server succeed.");
}
}