群聊服务端代码

package com.mytest.netty.nio.groupChat;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;
import java.util.Set;

public class GroupChatServer {

    //定义相关属性
    private Selector selector;
    private ServerSocketChannel listenChannel;
    private static final int PORT = 6666;

    //初始化工作
    public GroupChatServer() {
        try{
            //得到选择器
            selector = Selector.open();
            //得到ServerSocketChannel
            listenChannel = ServerSocketChannel.open();
            //绑定端口
            listenChannel.socket().bind(new InetSocketAddress(PORT));
            //设置非阻塞模式
            listenChannel.configureBlocking(false);
            //将listenChannel注册到selector上
            listenChannel.register(selector, SelectionKey.OP_ACCEPT);
        }catch (IOException e) {
            e.printStackTrace();
        }
    }

    //监听的代码
    public void listen(){
        try{
            while (true) {

                int count = selector.select();
                if (count > 0) {//有事件处理
                    Set<SelectionKey> selectionKeys = selector.selectedKeys();
                    Iterator<SelectionKey> iterator = selectionKeys.iterator();
                    while (iterator.hasNext()) {
                        //取出selectionKey
                        SelectionKey key = iterator.next();

                        //监听到accpet
                        if (key.isAcceptable()) {
                            SocketChannel sc = listenChannel.accept();

                            //设置非阻塞
                            sc.configureBlocking(false);

                            //将该sc注册到selector
                            sc.register(selector, SelectionKey.OP_READ);
                            //给出上线提示
                            System.out.println(sc.getRemoteAddress() + "上线 ");
                        }

                        if (key.isReadable()) {//通道发生read事件
                            //处理读事件
                            readData(key);
                        }

                        //删除当前key，防止重复处理
                        iterator.remove();
                    }
                } else {//等待
                    System.out.println("等待中。。。。。");
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {

        }
    }

    //读取客户端消息
    private void readData(SelectionKey key) {
        //定义一个socketChannel
        SocketChannel channel = null;
        try{
            //得到channel
            channel = (SocketChannel) key.channel();
            //创建Buffer
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            int count = channel.read(buffer);

            //根据count的值做处理
            if (count > 0) {
                //将缓冲区的数据转为字符串并输出
                String msg = new String(buffer.array());
                //输出该消息
                System.out.println(channel.getRemoteAddress() + "：" + msg);

                //向其他客户端转发消息(去掉自己)
                sendInfoToOtherClients(msg, channel);
            }

        } catch (IOException e) {
            try{
                //处理发送过程中断开链接的情况
                System.out.println(channel.getRemoteAddress() + "已离线。。。");
                //取消注册
                key.cancel();
                //关闭通道
                channel.close();
            }catch (IOException e1) {
                e1.printStackTrace();
            }
        }
    }

    //转发消息给其他客户（通道）
    private void sendInfoToOtherClients(String msg, SocketChannel self) throws IOException{

        System.out.println("服务器消息发送中。。。");
        for (SelectionKey key : selector.keys()) {
            //通过key， 去除对应的SocketChannel
            Channel targetChannel = key.channel();  //使用Channel也可以接受，因为SocketChannel实现了Channel

            //排除自己的Channel
            if (targetChannel instanceof SocketChannel && !self.equals(targetChannel)) {
                SocketChannel dest = (SocketChannel) targetChannel;
                //将msg 存储到Buffer
                ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
                //将buffer的数据写入到通道中
                dest.write(buffer);
            }
        }
    }

    public static void main(String[] args) {

        //创建一个服务器对象
        GroupChatServer chatServer = new GroupChatServer();

        //监听
        chatServer.listen();
    }
}

客户端代码

package com.mytest.netty.nio.groupChat;

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

public class GroupChatClient {

    //定义相关属性
    private final String HOST = "127.0.0.1";
    private static final int PORT = 6666;
    private Selector selector;
    private SocketChannel socketChannel;
    private String userName;

    //构造器
    public GroupChatClient() throws IOException {
        selector = Selector.open();
        //链接服务器
        socketChannel = socketChannel.open(new InetSocketAddress(HOST, PORT));

        //设置非阻塞
        socketChannel.configureBlocking(false);

        //将channel注册到selector
        socketChannel.register(selector, SelectionKey.OP_READ);

        //得到userName
        userName = socketChannel.getLocalAddress().toString().substring(1);
        System.out.println(userName + "is ok ....");
    }

    //向服务器发送消息
    public void sendInfo(String info){
        info = userName + "说：" + info;

        try{
            socketChannel.write(ByteBuffer.wrap(info.getBytes()));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //读取从服务端回复的数据
    public void readInfo() {
        try {
            int readChannels = selector.select(2000);
            if (readChannels > 0) {//有可以使用的通道
                Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                while (iterator.hasNext()) {

                    SelectionKey key = iterator.next();
                    if (key.isReadable()) {
                        //得到相关的通道
                        SocketChannel sc = (SocketChannel) key.channel();

                        //得到一个Buffer
                        ByteBuffer buffer = ByteBuffer.allocate(1024);
                        //读取
                        sc.read(buffer);
                        System.out.println(new String(buffer.array()));
                    }
                }
                iterator.remove();
            }else {
//                System.out.println("没有可用的通道");
            }
        }catch (IOException e) {
            e.printStackTrace();
        }
    }

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

        //启动客户端
        GroupChatClient chatClient = new GroupChatClient();

        //启动一个线程，每隔3S读取从服务器端发送的数据
        new Thread() {
            public void run() {

                while (true) {
                    chatClient.readInfo();
                    try {
                        Thread.currentThread().sleep(3000);
                    }catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }.start();

        //客户端发送数据给服务端
        Scanner scanner = new Scanner(System.in);

        while (scanner.hasNextLine()) {
            String s = scanner.nextLine();
            chatClient.sendInfo(s);
        }
    }
}