Java-NIO（八）：DatagramChannel

Java NIO中的DatagramChannel是一个能收发UDP包的通道。
操作步骤：
　　1）打开 DatagramChannel
　　2）接收/发送数据

同样它也支持NIO的非阻塞模式操作,例如：

 @Test

     public void send() throws IOException {

         DatagramChannel channel = DatagramChannel.open();

         channel.configureBlocking(false);

         ByteBuffer byteBuffer = ByteBuffer.allocate(1024);

         Scanner scanner = new Scanner(System.in);

         SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

         while (scanner.hasNext()) {

             String line = scanner.next();

             byteBuffer.put((format.format(new Date()) + ":" + line).getBytes());

             byteBuffer.flip();

             channel.send(byteBuffer, new InetSocketAddress("127.0.0.1", 9899));

             byteBuffer.clear();

         }

         channel.close();

     }

     @Test

     public void receive() throws IOException {

         DatagramChannel channel = DatagramChannel.open();

         channel.configureBlocking(false);

         channel.bind(new InetSocketAddress(9899));

         Selector selector = Selector.open();

         channel.register(selector, SelectionKey.OP_READ);

         while (selector.select() > 0) {

             Iterator<SelectionKey> selectionKeys = selector.selectedKeys().iterator();

             while (selectionKeys.hasNext()) {

                 SelectionKey selectionKey = selectionKeys.next();

                 if (selectionKey.isReadable()) {

                     ByteBuffer buffer = ByteBuffer.allocate(1024);

                     channel.receive(buffer);

                     buffer.flip();

                     System.out.println(new String(buffer.array(), 0, buffer.limit()));

                     buffer.clear();

                 }

                 selectionKeys.remove();

             }

         }

     }