//服务端通道
    private ServerSocketChannel channel;
    // 多路复用选择器
    private Selector selector;
    public chatServer() {
        try {
            channel = ServerSocketChannel.open();
            selector = Selector.open();
            SocketAddress address = new InetSocketAddress(6666);
            channel.socket().bind(address);
            channel.configureBlocking(false);
            channel.register(selector, SelectionKey.OP_ACCEPT);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    //    监听客户端变化
    public void listenClient() throws Exception {
        System.out.println("服务端开始监听客户端变化");
        while (true) {
        //获取需要处理的事件
            int num = selector.select();
            if (num == 0) {
                continue;
            }
            Set<SelectionKey> set = selector.selectedKeys();
            Iterator<SelectionKey> iterator = set.iterator();
            while (iterator.hasNext()) {
                SelectionKey key = iterator.next();
                iterator.remove();
                if (key.isAcceptable()) {
                  //获取连接
                    SocketChannel Clientchannel = channel.accept();
                    //设置非阻塞
                    Clientchannel.configureBlocking(false);
                    //注册任务
                    Clientchannel.register(selector, SelectionKey.OP_READ);
                    //打印用户上线日志
                    System.out.println("用户：" + Clientchannel.socket().getRemoteSocketAddress() + "上线了");
                    continue;
                } else if (key.isReadable()) {
                    readData(key);
                }
            }
        }
    }
//读取信息
    public void readData(SelectionKey key) {
        SocketChannel channel = null;
        try {
            //获取当前的信道
            channel = (SocketChannel) key.channel();
            //创建缓冲区
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            int read = channel.read(buffer);
            //>0代表有可读取的内容
            if (read > 0) {
                String msg = "用户" + channel.socket().getRemoteSocketAddress() + ":" + new String(buffer.array());
                //打印信息
                System.out.println(msg);
                sendToOther(msg, channel);
            }
        } catch (Exception e) {
            System.out.println("用户：" + channel.socket().getRemoteSocketAddress() + "下线了");
            key.cancel();
            try {
                channel.close();
            } catch (Exception e1) {
                e1.printStackTrace();
            }
        }
    }
//信息分发
    public void sendToOther(String msg, SocketChannel selfSocketChannel) throws Exception {
        //获得所有的信道，可以理解为获取所有的用户
        Set<SelectionKey> set = selector.keys();
        for (SelectionKey key : set) {
            Channel channel = key.channel();
            //判断这是一个用户，并且不是发信息的那个人
            //这个是一个 socketchannel 并且不等价与我们发信息的 selfsocketchannel
            if (channel instanceof SocketChannel && channel != selfSocketChannel) {
                SocketChannel socketChannel = (SocketChannel) channel;
                ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
                socketChannel.write(buffer);
            }
        }
    }
//启动客户端，等待连接
    public static void main(String[] args) throws Exception {
        chatServer chatServer = new chatServer();
        chatServer.listenClient();
    }

   //服务端通道
    private SocketChannel channel;
    // 多路复用选择器
    private Selector selector;
    public chatClient() throws Exception {
        channel = SocketChannel.open();
        selector = Selector.open();
        SocketAddress address = new InetSocketAddress("127.0.0.1", 6666);
        channel.connect(address);
        channel.configureBlocking(false);
        channel.register(selector, SelectionKey.OP_READ);
        System.out.println("用户：" + channel.getLocalAddress() + "上线了");
    }
    public void sendData(String msg) {
        try {
            ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
            channel.write(buffer);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public void readData() throws Exception {
        SocketChannel channel = null;
        while (true) {
            int num = selector.select();
            if (num == 0) {
                continue;
            }
            Set<SelectionKey> set = selector.selectedKeys();
            Iterator<SelectionKey> iterator = set.iterator();
            while (iterator.hasNext()) {
                SelectionKey key = iterator.next();
                iterator.remove();
                if (key.isReadable()) {
                    try {
                        //获取当前的信道
                        channel = (SocketChannel) key.channel();
                        //创建缓冲区
                        ByteBuffer buffer = ByteBuffer.allocate(1024);
                        int read = channel.read(buffer);
                        //>0代表有可读取的内容
                        if (read > 0) {
                            String msg = new String(buffer.array());
                            System.out.println(msg);
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }
    public static void main(String[] args) throws Exception {
        final chatClient client = new chatClient();
        new Thread() {
            @Override
            public void run() {
                while (true) {
                    try {
                        //一直阅读是否有信息
                        client.readData();
                        //每一秒阅读一次
                        sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }
        }.start();
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextLine()) {
            String str = scanner.nextLine();
            client.sendData(str);
        }
    }