Java网络编程之UDP

图一：

示例代码：

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;

import org.junit.Test;

public class TestUDP {
	// 发送端
	@Test
	public void send() {
		DatagramSocket ds = null;
		try {
			ds = new DatagramSocket();

			byte[] b = "我是要发送的信息!".getBytes();
			//创建一个数据报：每一个数据报不能大于64k，都记录着数据信息，发送端的IP、端口号,以及要发送到
			//的接收端的IP、端口号。
			DatagramPacket dp = new DatagramPacket(b, 0, b.length, InetAddress.getByName("127.0.0.1"), 9898);
			ds.send(dp);
		} catch (SocketException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if(ds != null) {
				ds.close();
			}
		}
	}

	// 接收端
	@Test
	public void receive() {
		DatagramSocket ds = null;
		try {
			ds = new DatagramSocket(9898);

			byte[] b = new byte[1024];

			DatagramPacket dp = new DatagramPacket(b, 0, b.length);
			ds.receive(dp);

			//String str = new String(b, 0, b.length);
			String str = new String(dp.getData(), 0, dp.getLength());
			System.out.println(str);
		} catch (SocketException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if(ds != null) {
				ds.close();
			}
		}
	}
}