package chapter5;

import java.io.IOException;

import java.net.InetSocketAddress;

import java.nio.channels.SelectionKey;

import java.nio.channels.Selector;

import java.nio.channels.ServerSocketChannel;

import java.util.Iterator;

public class TCPServerSelector {

	private static final int BUFSIZE = 256;  //Buffer,EchoSelectorProtocol

	private static final int TIMEOUT = 3000; //Selector.select(long timeout) 

	public static void main(String[] args) throws IOException {

		if(args.length<1){

			throw new IllegalArgumentException("Parameter(s): <Port> ...");

		}

		Selector selector =Selector.open(); //创建Selector实例

		for(String arg:args){

			ServerSocketChannel listnChannel =ServerSocketChannel.open();

			listnChannel.socket().bind(new InetSocketAddress(Integer.parseInt(arg)));

			listnChannel.configureBlocking(false); //nonblocking

			listnChannel.register(selector, SelectionKey.OP_ACCEPT); //Channel注册selector,并告知channel感兴趣的操作

		}

		TCPProtocol protocol =new EchoSelectorProtocol(BUFSIZE);

		while(true){ //循环

			if(selector.select(TIMEOUT)==0){ //返回准备就绪I/O的SelectionKey数

				System.out.println("."); //to do others

				continue;

			}

			Iterator<SelectionKey> keyIter =selector.selectedKeys().iterator();//获取已选的SelectionKey集合

			while(keyIter.hasNext()){ //遍历key,根据key的类型做相应处理

				SelectionKey key =keyIter.next();

				if(key.isAcceptable())

					protocol.handleAccept(key);

				if(key.isReadable())

					protocol.handleRead(key);

				//SelectionKey is invalid if it is cancelled, its channel is closed, or its selector is closed.

				if(key.isValid() && key.isWritable())

					protocol.handleWrite(key);

				keyIter.remove(); //手动清空,因为Selector只会在已选的SelectionKey集中添加

			}

		}

	}

}

package chapter5;

import java.io.IOException;

import java.nio.channels.SelectionKey;

public interface TCPProtocol {

	void handleAccept(SelectionKey key) throws IOException;

	void handleRead(SelectionKey key) throws IOException;

	void handleWrite(SelectionKey key) throws IOException;

}

package chapter5;

import java.io.IOException;

import java.nio.ByteBuffer;

import java.nio.channels.SelectionKey;

import java.nio.channels.ServerSocketChannel;

import java.nio.channels.SocketChannel;

public class EchoSelectorProtocol implements TCPProtocol {

	private int bufSize;

	public EchoSelectorProtocol(int bufSize){

		this.bufSize =bufSize;

	}

	@Override

	public void handleAccept(SelectionKey key) throws IOException {

		SocketChannel clntChan = ((ServerSocketChannel)key.channel()).accept();

		clntChan.configureBlocking(false);

		//对于已注册Selector的Channel,再次调用就更新注册信息,这里更新了SelectionKey的类型和附件,附件是需要操作的buffer.

		clntChan.register(key.selector(), SelectionKey.OP_READ,ByteBuffer.allocate(bufSize));

	}

	@Override

	public void handleRead(SelectionKey key) throws IOException {

		SocketChannel clntChan =(SocketChannel)key.channel();

		ByteBuffer buf =(ByteBuffer) key.attachment(); //获取附件

		long bytesRead = clntChan.read(buf);

		if(bytesRead==-1) //channel已读到结束位置

			clntChan.close();

		else if(bytesRead > 0)

			key.interestOps(SelectionKey.OP_READ|SelectionKey.OP_WRITE);

	}

	@Override

	public void handleWrite(SelectionKey key) throws IOException {

		ByteBuffer buf =(ByteBuffer) key.attachment();

		buf.flip();

		SocketChannel clntChan =(SocketChannel) key.channel();

		clntChan.write(buf);

		if(!buf.hasRemaining()){

			key.interestOps(SelectionKey.OP_READ); //设置Key的兴趣集

		}

		buf.compact();

	}

}