Java 非阻塞式NIO 案例（实现多人聊天功能）

 1     public static void main(String[] args) throws Exception {
 2         SocketChannel sChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 8989));
 3 
 4         //2. 切换非阻塞模式
 5         sChannel.configureBlocking(false);
 6 
 7         //3. 分配指定大小的缓冲区
 8         ByteBuffer buf = ByteBuffer.allocate(1024);
 9 
10         //4. 发送数据给服务端
11         Scanner scan = new Scanner(System.in);
12 
13         while (scan.hasNext()) {
14             String str = scan.next();
15             buf.put((new Date().toString() + "\n" + str).getBytes());
16             buf.flip();
17             sChannel.write(buf);
18             buf.clear();
19         }
20 
21         //5. 关闭通道
22         sChannel.close();
23     }

    @Test
    public void server() {
        ServerSocketChannel ssChannel = null;
        try {
            ssChannel = ServerSocketChannel.open();
            //配置非阻塞
            ssChannel.configureBlocking(false);
            //绑定连接
            ssChannel.bind(new InetSocketAddress(8989));

            Selector selector = Selector.open();

            //将通道注册到监听器中，并且制定监听器的监听模式为“接受”
            ssChannel.register(selector, SelectionKey.OP_ACCEPT);

            //轮询的选择已经就绪的事件
            while (selector.select() > 0) {
                //获取当前监听
                Iterator<SelectionKey> it = selector.selectedKeys().iterator();

                while (it.hasNext()) {
                    //获取准备就绪的事件
                    SelectionKey sk = it.next();
                    if (sk.isAcceptable()) {
                        //如果接受就绪，则获取客户端的连接
                        SocketChannel clientChannel = ssChannel.accept();

                        //同样配置成非阻塞式
                        clientChannel.configureBlocking(false);

                        //把客户端的连接注册到选择器上
                        clientChannel.register(selector, SelectionKey.OP_READ);
                    } else if (sk.isReadable()) {
                        //如果读取就绪，则获取读取的通道
                        SocketChannel socketChannel = (SocketChannel) sk.channel();

                        //配置成非阻塞模式
                        socketChannel.configureBlocking(false);

                        //读取数据

                        ByteBuffer byteBuffer = ByteBuffer.allocate(1024);

                        int len = 0;
                        while ((len = socketChannel.read(byteBuffer)) > 0) {
                            byteBuffer.flip();
                            System.out.println(new String(byteBuffer.array(), 0, len));
                            byteBuffer.clear();
                        }
                    }
                    it.remove();
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if(ssChannel!=null){
                try {
                    ssChannel.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }