nserver.java

疯狂Java讲义_源码(含Java设计模式CHM

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

/**
 * Description:
 * <br/>Copyright (C), 2008-2010, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee [e-mail]
 * @version  1.0
 */
public class NServer
{
	//用于检测所有Channel状态的Selector
	private Selector selector = null;
	//定义实现编码、解码的字符集对象
	private Charset charset = Charset.forName("UTF-8");
    public void init()throws IOException
    {
		selector = Selector.open();
		//通过open方法来打开一个未绑定的ServerSocketChannel实例
		ServerSocketChannel server = ServerSocketChannel.open();
		InetSocketAddress isa = new InetSocketAddress(
			"127.0.0.1", 30000); 
		//将该ServerSocketChannel绑定到指定IP地址
		server.socket().bind(isa);
		//设置ServerSocket以非阻塞方式工作
		server.configureBlocking(false);
		//将server注册到指定Selector对象
		server.register(selector, SelectionKey.OP_ACCEPT);
		while (selector.select() > 0) 
		{
			//依次处理selector上的每个已选择的SelectionKey
			for (SelectionKey sk : selector.selectedKeys())
			{
				//从selector上的已选择Key集中删除正在处理的SelectionKey
				selector.selectedKeys().remove(sk);
				//如果sk对应的通道包含客户端的连接请求
				if (sk.isAcceptable())
				{
					//调用accept方法接受连接，产生服务器端对应的SocketChannel
					SocketChannel sc = server.accept();
					//设置采用非阻塞模式
					sc.configureBlocking(false);
					//将该SocketChannel也注册到selector
					sc.register(selector, SelectionKey.OP_READ);
					//将sk对应的Channel设置成准备接受其他请求
					sk.interestOps(SelectionKey.OP_ACCEPT);
				}
				//如果sk对应的通道有数据需要读取
				if (sk.isReadable())
				{
					//获取该SelectionKey对应的Channel，该Channel中有可读的数据
					SocketChannel sc = (SocketChannel)sk.channel();
					//定义准备执行读取数据的ByteBuffer
					ByteBuffer buff = ByteBuffer.allocate(1024);
					String content = "";
					//开始读取数据
					try
					{
						while(sc.read(buff) > 0)
						{
							buff.flip();
							content += charset.decode(buff);
						}
						//打印从该sk对应的Channel里读取到的数据
						System.out.println("=====" + content);
						//将sk对应的Channel设置成准备下一次读取
						sk.interestOps(SelectionKey.OP_READ);
					}
					//如果捕捉到该sk对应的Channel出现了异常，即表明该Channel
					//对应的Client出现了问题，所以从Selector中取消sk的注册
					catch (IOException ex)
					{
						//从Selector中删除指定的SelectionKey
						sk.cancel();
						if (sk.channel() != null)
						{
							sk.channel().close();
						}
					}
					//如果content的长度大于0，即聊天信息不为空
					if (content.length() > 0)
					{
						//遍历该selector里注册的所有SelectKey
						for (SelectionKey key : selector.keys())
						{
							//获取该key对应的Channel
							Channel targetChannel = key.channel();
							//如果该channel是SocketChannel对象
							if (targetChannel instanceof SocketChannel)
							{
								//将读到的内容写入该Channel中
								SocketChannel dest = (SocketChannel)targetChannel;
								dest.write(charset.encode(content));
							}
						}
					}
				}
			}
		}
    }
	
	public static void main(String[] args)
		throws IOException
	{
		new NServer().init();
	}
}