Nio实现简单的群聊系统

首先是服务端代码

public class GroupChatServer {
    private Selector selector;
    private ServerSocketChannel listenChannel;
    private static final  int PORT = 6666;
    public GroupChatServer(){
        try{
            selector=Selector.open();
            listenChannel = ServerSocketChannel.open();
            listenChannel.socket().bind(new InetSocketAddress(PORT));
            listenChannel.configureBlocking(false);
            listenChannel.register(selector, SelectionKey.OP_ACCEPT);
        }catch (IOException e){
            e.printStackTrace();
        }
    }
    //监听
    public void listen(){
        try {
            while(true){
                int count = selector.select(2000);
                if (count>0){
                    //修相关的事件处理
                    Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                    while(iterator.hasNext()){
                        SelectionKey key = iterator.next();
                        if(key.isAcceptable()){
                            SocketChannel socketChannel = listenChannel.accept();
                            socketChannel.configureBlocking(false);
                            socketChannel.register(selector,SelectionKey.OP_READ);
                            System.out.println(socketChannel.getRemoteAddress()+"上线了");
                        }
                        if(key.isReadable()){//通道发生read事件，通道可读状态
                            readData(key);
                        }

                        iterator.remove();
                    }

                }else {
                    continue;
                   // System.out.println("服务器等待中");
                }
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {

        }
    }
    //读取客户端消息
    private void readData(SelectionKey selectionKey){
        //定义一个
        SocketChannel socketChannel = null;
        try {
            socketChannel = (SocketChannel)selectionKey.channel();
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            int count = socketChannel.read(buffer);
            if(count>0){
                //把缓冲区的数据转会字符串
                String msg = new String(buffer.array());
                System.out.println("from client"+msg.trim());
                //向其他客户端转发消息
                sendInfo(msg,socketChannel);
            }
        }catch (IOException e){
            try {
                System.out.println(socketChannel.getRemoteAddress()+"离线了");
                selectionKey.cancel();
                socketChannel.close();
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
    }
    //转发消息给其他客户
    private void sendInfo(String msg,SocketChannel self) throws IOException {
        System.out.println("服务器转发消息");
        //遍历所有注册到selector的SocketChannel
        for(SelectionKey key : selector.keys()){
            Channel tagetChannel = key.channel();

            if(tagetChannel instanceof SocketChannel && tagetChannel!=self){
                SocketChannel dest =(SocketChannel)tagetChannel;
                ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
                dest.write(buffer);
            }
        }
    }
    public static void main(String[] args) throws IOException {
        GroupChatServer groupChatServer = new GroupChatServer();
        groupChatServer.listen();
    }
}


下来是客户端代码

public class GroupChatClient {
    private final String HOST ="127.0.0.1";
    private final int PORT = 6666;
    private Selector selector;
    private SocketChannel socketChannel;
    private String username;
    //初始化
    public GroupChatClient() throws IOException {
        selector = Selector.open();
        socketChannel=socketChannel.open(new InetSocketAddress(HOST,PORT));
        socketChannel.configureBlocking(false);
        socketChannel.register(selector, SelectionKey.OP_READ);
        username = socketChannel.getLocalAddress().toString().substring(1);
        System.out.println(username+"is ok...");
    }
    public void sendInfo(String info){
        info = username +"："+info;
        try{
            socketChannel.write(ByteBuffer.wrap(info.trim().getBytes(StandardCharsets.UTF_8)));
        }catch (IOException e){
            e.printStackTrace();
        }
    }
    public void readInfo(){
        try{
            int select = selector.select(2000);
            if(select>0){
                Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                while(iterator.hasNext()){
                    SelectionKey key = iterator.next();
                    if(key.isReadable()){
                        //获取相关通道
                        SocketChannel channel = (SocketChannel) key.channel();

                        ByteBuffer buffer = ByteBuffer.allocate(1024);
                        channel.read(buffer);
                        String msg = new String(buffer.array());
                        System.out.println(msg.trim());
                    }else {
                        continue;
                    }
                    iterator.remove();
                }
            }
        }catch (IOException e){
            e.printStackTrace();
        }
    }
    public static void main(String[] args) throws IOException {
        GroupChatClient chatClient = new GroupChatClient();

        new Thread(){
            public void run(){
                while(true){
                    chatClient.readInfo();

                    try {
                        Thread.currentThread().sleep(3000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }.start();
        Scanner scanner = new Scanner(System.in);
        while(scanner.hasNextLine()){
            String s = scanner.nextLine();
            chatClient.sendInfo(s);
        }
    }
}