public class UDPRunnable extends Thread{

DatagramPacket packet;;

//初始化DatagramPacket, DatagramSocket

public UDPRunnable(DatagramPacket packet){

this.packet=packet;

}

public void run() {

byte[] data=packet.getData();//!!!這里應(yīng)該使用packet的getData方法來創(chuàng)建data字節(jié)，不然data字節(jié)中為空值

String info=new String(data,0,packet.getLength());//

System.out.println("我是服務(wù)器，客戶端說："+info);

/*

* 服務(wù)器向客戶端發(fā)送響應(yīng)信息

*/

//需要知道客戶端的address，port，并且創(chuàng)建需要發(fā)送的消息

InetAddress address=packet.getAddress();

int port=packet.getPort();

byte[] data2="客戶端登陸成功，歡迎使用服務(wù)器".getBytes();

//創(chuàng)建DatagramPacket

DatagramPacket packet2=new DatagramPacket(data2,data2.length,address,port);

try {

DatagramSocket socket=new DatagramSocket();

socket.send(packet2);

} catch (SocketException e) {

// TODO Auto-generated catch block

e.printStackTrace();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}

public class UDPClient {

public static void main(String[] args) throws IOException {

/*

* 向服務(wù)器端發(fā)送消息

*/

//1.需要獲取服務(wù)器端的地址，端口號

InetAddress address=InetAddress.getByName("localhost");

int port=6605;

byte[] message="用戶名：admin 密碼:123".getBytes();

//創(chuàng)建數(shù)據(jù)報

DatagramPacket packet=new DatagramPacket(message,message.length,address,port);

//創(chuàng)建DatagramSocket

DatagramSocket socket=new DatagramSocket();

socket.send(packet);

/*

* 接收服務(wù)器端發(fā)送的響應(yīng)消息

*/

//創(chuàng)建DatagramPacket

byte[] data=new byte[10*1024];

DatagramPacket packet2=new DatagramPacket(data,data.length);

socket.receive(packet2);

String reply=new String(data,0,packet.getLength());

System.out.println("我是客戶端，服務(wù)器說："+reply);

}

}

客戶端輸出結(jié)果： ?客戶端啟動成功，歡迎使 ? ?