基于AIO的CS聊天室

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所谓AIO，即是异步IO，它的IO操作交由操作系统完成。设置监听器（类似于一个信号处理函数），当系统IO操作完成时，会被监听器监听到，并执行相应的后续操作，然后返回。

监听器一般使用CompletionHandler。

服务器端代码： 

package com.nanhao.AIOTest;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.*;
import java.nio.channels.AsynchronousChannelGroup;
import java.nio.channels.AsynchronousServerSocketChannel;
import java.nio.channels.AsynchronousSocketChannel;
import java.nio.channels.CompletionHandler;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Server {

    static final int PORT = 3000;
    final static String UTF_8 = "utf-8";
    static List<AsynchronousSocketChannel>channelList = new ArrayList<>();

    public void startListen()throws IOException,Exception{

        //创建一个线程池
        ExecutorService executorService = Executors.newFixedThreadPool(20);
        //以指定的线程池来创建一个AsynchronousChannelGroup
        AsynchronousChannelGroup channelGroup = AsynchronousChannelGroup.withThreadPool(executorService);
        //通过channelGroup来创建一个AsynchronousServerSocketChannel
        AsynchronousServerSocketChannel serverSocketChannel = AsynchronousServerSocketChannel.open(channelGroup)
                //指定监听本机的端口
                .bind(new InetSocketAddress("127.0.0.1",PORT));
        //使用监听器来接收来自客户端的链接请求
        serverSocketChannel.accept(null,new AcceptHandler(serverSocketChannel));
    }
    public static void main(String[]args)throws Exception{
        Server server = new Server();
        server.startListen();

    }
     class AcceptHandler implements CompletionHandler<AsynchronousSocketChannel,Object>{

        private AsynchronousServerSocketChannel serverSocketChannel;


        public AcceptHandler(AsynchronousServerSocketChannel serverSocketChannel) {
            this.serverSocketChannel = serverSocketChannel;
        }

        //定义一个ByteBuffer准备读取数据
        ByteBuffer byteBuffer = ByteBuffer.allocate(1024);

        @Override
        public void completed(final AsynchronousSocketChannel result, Object attachment) {
            Server.channelList.add(result);
            serverSocketChannel.accept(null,this);
            result.read(byteBuffer, null, new CompletionHandler<Integer, Object>() {


                @Override
                public void completed(Integer result, Object attachment) {
                    byteBuffer.flip();
                    //将buffer中的字节转换为字符
                    String context = StandardCharsets.UTF_8.decode(byteBuffer).toString();
                    //由于是聊天室，所以将所有的channel里面写入这个消息
                    for(AsynchronousSocketChannel ass:Server.channelList){
                        try{

                            ass.write(ByteBuffer.wrap(context.getBytes(Server.UTF_8))).get();

                        }catch(Exception e){
                            e.printStackTrace();
                        }
                    }
                    byteBuffer.clear();
                    result.read(byteBuffer,null,this);
                }

                @Override
                public void failed(Throwable exc, Object attachment) {


                    System.out.println("读取数据失败： "+exc);
                    Server.channelList.remove(result);


                }
            });

        }

         @Override
         public void failed(Throwable exc, Object attachment) {
            System.out.println("连接失败 ："+exc);

         }
     }


}