javaNIO-实现群聊功能

服务端

public class GroupChatServer {

    //定义属性
    private Selector selector;
    private ServerSocketChannel listenChannel;
    private static final int PORT = 6667;

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

    //监听
    public void listen(){
        try {
            //循环处理
            while (true){
                int count = selector.select(2000);
                if (count > 0){//有事件处理
                    //遍历selectionKey
                    Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                    while (iterator.hasNext()){
                        SelectionKey key = iterator.next();
                        //监听到accept
                        if (key.isAcceptable()){
                            SocketChannel sc = listenChannel.accept();
                            sc.configureBlocking(false);
                            //将该sc注册到seletor上
                            sc.register(selector,SelectionKey.OP_READ);
                            System.out.println(sc.getRemoteAddress()+" 上线");
                        }
                        //监听read（通道可读）
                        if (key.isReadable()){
                            //处理读
                            readData(key);
                        }
                        //当前的key删除，防止重复处理
                        iterator.remove();
                    }
                }else {
                    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 {
            //取到关联的channel
            channel = (SocketChannel) key.channel();
            //创建buffer
            ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
            int count = channel.read(byteBuffer);
            if (count >0){//是否读到数据
                String msg = new String(byteBuffer.array());
                System.out.println("客户端消息："+msg);
                //向其他客户端转发消息
                sendInfoToOtherClients(msg,channel);
            }
        }catch (IOException e){
            try {
                System.out.println(channel.getRemoteAddress()+" 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），排除自己
    private void sendInfoToOtherClients(String msg,SocketChannel self) throws IOException {
        System.out.println("服务器转发消息");
        //遍历所有注册到selector上的Channel
        for (SelectionKey key : selector.keys()) {
            //通过key取出对应的SocketChannel
            Channel channel = key.channel();
            //排除自己
            if (channel instanceof SocketChannel && channel != self){
                SocketChannel dest = (SocketChannel) channel;
                //将msg存储到buffer
                ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
                //将buffer的数据写入通道
                dest.write(buffer);
            }
        }
    }
}

启动服务端

        GroupChatServer server = new GroupChatServer();
        server.listen();

客户端

public class GroupChatClient {
    //定义属性
    private final String HOST = "127.0.0.1";
    private final int PORT = 6667;
    private Selector selector;
    private SocketChannel socketChannel;
    private String username;

    //初始化
    @SneakyThrows
    public GroupChatClient(){
        selector = Selector.open();
        //连接服务器
        socketChannel = SocketChannel.open(new InetSocketAddress(HOST,PORT));
        //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 + " ok");
    }

    //向服务器发送消息
    public void sendInfo(String msg){
        msg = username+":"+msg;
        try {
            //发送
            socketChannel.write(ByteBuffer.wrap(msg.getBytes()));
        }catch (IOException e){
            e.printStackTrace();
        }
    }

    //读取从服务器回复的消息
    public void readInfo(){
        try {
            int read = selector.select();
            if (read > 0){//有可用的通道
                Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                while (iterator.hasNext()){
                    SelectionKey key = iterator.next();
                    if (key.isReadable()){
                        //得到相关通道
                        SocketChannel sc = (SocketChannel) key.channel();
                        //得到一个buffer
                        ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
                        sc.read(byteBuffer);
                        System.out.println(new String(byteBuffer.array()));
                    }
                    iterator.remove();//删除当前SelectionKey防止重复
                }
            }
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

启动客户端

        GroupChatClient client = new GroupChatClient();

        //启动一个线程，每三秒从服务器发送的数据
        new Thread(){
            @Override
            public void run() {
                while (true){
                    client.readInfo();
                    try {
                        Thread.currentThread().sleep(3000);
                    }catch (InterruptedException e){
                        e.printStackTrace();
                    }
                }
            }
        }.start();

        //发送数据
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextLine()){
            String s = scanner.nextLine();
            client.sendInfo(s);
        }