package udp; 
 
import java.net.*; 
 
/** 
 * @说明 UDP客户端程序，用于对服务端发送数据，并接收服务端的回应信息 
 * @author cuisuqiang 
 * @version 1.0 
 * @since <a href="mailto:cuisuqiang@163.com" rel="external nofollow" >cuisuqiang@163.com</a> 
 */ 
public class UdpClientSocket { 
  /** 
   * 连接对象 
   */ 
  private static DatagramSocket ds = null; 
  /** 
   * 地址对象 
   */ 
  private static SocketAddress address = null; 
   
  /** 
   * 测试客户端发包和接收回应信息的方法 
   */ 
  public static void main(String[] args) throws Exception { 
    init(); 
    while(true){ 
      UdpClientSocket.send(address,"你好，亲爱的!".getBytes()); 
      UdpClientSocket.receive(); 
      try { 
        Thread.sleep(3 * 1000); 
      } catch (Exception e) { 
        e.printStackTrace(); 
      } 
    } 
  } 
   
  /** 
   * 对连接和地址初始化 
   */ 
  public static void init(){ 
    try { 
      ds = new DatagramSocket(8899); // 邦定本地端口作为客户端 
      ds.setSoTimeout(2 * 1000); 
      address = new InetSocketAddress("127.0.0.1",3344); 
    } catch (Exception e) { 
      e.printStackTrace(); 
    } 
  } 
   
  /** 
   * 向指定的服务端发送数据信息 
   */ 
  public static void send(SocketAddress address,byte[] bytes){ 
    try { 
      DatagramPacket dp = new DatagramPacket(bytes, bytes.length, address); 
      ds.send(dp); 
    } catch (Exception e) { 
      e.printStackTrace(); 
    } 
  } 
 
  /** 
   * 接收从指定的服务端发回的数据 
   */ 
  public static void receive(){ 
    try { 
      byte[] buffer = new byte[1024]; 
      DatagramPacket dp = new DatagramPacket(buffer, buffer.length); 
      ds.receive(dp);    
      byte[] data = new byte[dp.getLength()]; 
      System.arraycopy(dp.getData(), 0, data, 0, dp.getLength());  
      System.out.println("服务端回应数据：" + new String(data)); 
    } catch (Exception e) { 
      e.printStackTrace(); 
    } 
  } 
} 

package udp;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketAddress;

/**
 * @说明 UDP服务类
 * @author cuisuqiang
 * @version 1.0
 * @since cuisuqiang@163.com
 */
public class UdpServerSocket {
	
	private static DatagramSocket ds = null;
	private static SocketAddress address = null;
	
	/**
	 * 测试方法
	 */
	public static void main(String[] args) throws Exception {
		init();
		System.out.println("---->服务开始监听！<----");
		while (true) {
			UdpServerSocket.receive();
			UdpServerSocket.response(address,"你好,吃了吗!");
		}		
	}
	
	public static void init(){
		try {
			ds = new DatagramSocket(3344);
			ds.setSoTimeout(0);
			address = new InetSocketAddress("127.0.0.1",8899);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	/**
	 * 接收数据包，该方法会造成线程阻塞
	 */
	public static void receive() {
		try {
			byte[] buffer = new byte[1024];
			DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
			ds.receive(packet);
			String info = new String(packet.getData(), 0, packet.getLength());
			System.out.println("接收信息：" + info);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	/**
	 * 将响应包发送给请求端
	 */
	public static void response(SocketAddress address,String info){
		try {
			DatagramPacket dp = new DatagramPacket(info.getBytes(), info.getBytes().length, address);
			dp.setData(info.getBytes());
			ds.send(dp);
		} catch (Exception e) {
			e.printStackTrace();
		}		
	}
}