NIO之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：

public static void main(String[] args){
        new Thread(new Runnable() {
            @Override
            public void run() {
                server();
            }
        }).start();
        
        new Thread(new Runnable() {
            @Override
            public void run() {
                client();
            }
        }).start();
    }
    
    // udp,非阻塞io,客户端
    public static void client(){
        DatagramChannel datagramChannel = null;
        try {
            // 1.获取通道
            datagramChannel = DatagramChannel.open();
            // 2.置为非阻塞模式
            datagramChannel.configureBlocking(false);
            // 3.分配缓冲区
            ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
            
            while (true) {                
                Thread.sleep(3000);
                // 4.向缓冲区放数据
                byteBuffer.put(("时间："+CommonUtil.getDateTime()+"，编号："+UUID.randomUUID().toString()).getBytes());
                byteBuffer.flip();
                // 5.通道向服务端发送
                datagramChannel.send(byteBuffer, new InetSocketAddress("127.0.0.1", 2787));
                byteBuffer.clear();
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        } finally{
            if (datagramChannel!=null) {
                try {
                    datagramChannel.close();
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }
        }
    }
    // udp,非阻塞io,服务端
    public static void server(){
        DatagramChannel datagramChannel = null;
        try {
            // 1.获取通道
            datagramChannel = DatagramChannel.open();
            // 2.置为非阻塞模式
            datagramChannel.configureBlocking(false);
            // 3.绑定监听端口
            datagramChannel.bind(new InetSocketAddress(2787));
            // 4.获取选择器
            Selector selector = Selector.open();
            // 5.通道注册选择器
            datagramChannel.register(selector, SelectionKey.OP_READ);
            // 5.获取选择器上的已选择的键
            while (selector.select()>0) {
                Iterator<SelectionKey> it = selector.selectedKeys().iterator();
                while (it.hasNext()) {
                    SelectionKey skey = it.next();
                    // 7.判断当前键的监听事件
                    if (skey.isConnectable()) {
                        System.out.println("connectable");
                    }else if (skey.isAcceptable()) {
                        System.out.println("acceptable");
                    }else if (skey.isReadable()) {
                        System.out.println("readable");
                        ByteBuffer mBuffer = ByteBuffer.allocate(1024);
                        datagramChannel.receive(mBuffer);
                        mBuffer.flip();
                        System.out.println("receive:"+new String(mBuffer.array(), 0, mBuffer.array().length));
                        mBuffer.clear();
                    }
                }
                it.remove();
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        } finally{
            if (datagramChannel!=null) {
                try {
                    datagramChannel.close();
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }
        }
    }

结果

readable
receive:时间：2017-01-01 19:01:46，编号：63feeb8f-7ead-4e2f-a65b-8471ef3940e3
readable
receive:时间：2017-01-01 19:01:46，编号：63feeb8f-7ead-4e2f-a65b-8471ef3940e4
readable
receive:时间：2017-01-01 19:01:46，编号：63feeb8f-7ead-4e2f-a65b-8471ef3940e5
readable
receive:时间：2017-01-01 19:01:46，编号：63feeb8f-7ead-4e2f-a65b-8471ef3940e6