Java 网络编程（六）UDP

UDP

发短信：不用连接，需要知道对方的地址

客户端：

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//不需要连接服务器 public class UdpClientDemo01 {     public static void main(String[] args) throws Exception{         //1.建立一个Socket         DatagramSocket socket = new DatagramSocket();         //2.建个包         String msg = "你好啊！";         //发送给谁         InetAddress localhost = InetAddress.getByName("localhost");         int port = 9090;         DatagramPacket datagramPacket = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,localhost,port);         //3.发送包         socket.send(datagramPacket);         //4.关闭流         socket.close();     } }

 

接收端：

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//还要等待客户端的连接 public class UdpServerDemo01 {     public static void main(String[] args) throws Exception{         //开放端口         DatagramSocket socket = new DatagramSocket(9090);         //接收数据         byte[] buffer = new byte[1024];         DatagramPacket datagramPacket = new DatagramPacket(buffer, 0, buffer.length);         socket.receive(datagramPacket);//阻塞接受         System.out.println(datagramPacket.getAddress().getHostAddress());         //关闭连接         socket.close();     } }

　　

循环接收消息：

发送方：

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public class UdpSenderDemo01 {     public static void main(String[] args) throws Exception{         DatagramSocket socket = new DatagramSocket(8888);         //准备数据；控制台读取System.in         BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));         while (true) {             String data = reader.readLine();             byte[] datas = data.getBytes();             DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress("localhost", 6666));             socket.send(packet);             if (data.equals("bye")){                 break;             }         }         socket.close();     } }

　

接收方：

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public class UdpReceiveDemo01 {     public static void main(String[] args) throws Exception {         DatagramSocket socket = new DatagramSocket(6666);           while (true){             //准备接收包裹             byte[] container = new byte[1024];             DatagramPacket packet = new DatagramPacket(container,0,container.length);             //断开连接             byte[] data = packet.getData();             String receiveData = new String(data,0,data.length);             System.out.println(receiveData);             if (receiveData.equals("bye")){                 break;             }         }         socket.close();     } }