一个简单的Java UDP协议通信的例子server：
import java.net.*;public class UDPServer { private static final int PORT = 5000; private DatagramSocket dataSocket; private DatagramPacket dataPacket; private byte receiveByte[]; private String receiveStr; public UDPServer() { Init(); } public void Init() { try { dataSocket = new DatagramSocket(PORT); receiveByte = new byte[1024]; dataPacket = new DatagramPacket(receiveByte, receiveByte.length); receiveStr = ""; int i = 0; while (i == 0)// 无数据，则循环 { dataSocket.receive(dataPacket); i = dataPacket.getLength(); // 接收数据 if (i > 0) { // 指定接收到数据的长度,可使接收数据正常显示,开始时很容易忽略这一点 receiveStr = new String(receiveByte, 0, dataPacket.getLength()); System.out.println(receiveStr); i = 0;// 循环接收 } } } catch (Exception e) { e.printStackTrace(); } } public static void main(String args[]) { new UDPServer(); }}
client：
import java.io.*;import java.net.*;public class UDPClient { private static final int PORT = 4561; private DatagramSocket dataSocket; private DatagramPacket dataPacket; private byte sendDataByte[]; private String sendStr; public UDPClient() { Init(); } public void Init() { try { // 指定端口号，避免与其他应用程序发生冲突 dataSocket = new DatagramSocket(PORT+1); sendDataByte = new byte[1024]; sendStr = "UDP方式发送数据"; sendDataByte = sendStr.getBytes(); dataPacket = new DatagramPacket(sendDataByte, sendDataByte.length, InetAddress.getByName("localhost"), PORT); dataSocket.send(dataPacket); } catch (SocketException se) { se.printStackTrace(); } catch (IOException ie) { ie.printStackTrace(); } } public static void main(String args[]) { new UDPClient(); }}
