datagramreceiver.java

Java ME手机应用开发大全一书的配套光盘上的源码

import java.io.IOException;
import javax.microedition.io.Connector;
import javax.microedition.io.Datagram;
import javax.microedition.io.DatagramConnection;
import javax.microedition.midlet.*;

public class DatagramReceiver extends MIDlet{
  // MIDlet构造程序
  public DatagramReceiver() {}

  // 被应用程序管理器调用来启动MIDlet。
  public void startApp() {
   try {
	         //建立并打开数据报连接
            DatagramConnection receiver = 
                    (DatagramConnection)Connector.open("datagram://:5555");
			//声明接收数据的数组
            byte[] buffer = new byte[256];
			//构造Datagram对象
            Datagram dgram = receiver.newDatagram(buffer, buffer.length);
			//等待服务器发送消息
            for (;;) {
				//设置接收的数据报长度
                dgram.setLength(buffer.length);
				//接收数据
                receiver.receive(dgram);
                int length = dgram.getLength();
                System.out.println("Datagram received. Length is " + length);

                // 显示接收到的数据报中的数据
                for (int i = 0; i < length; i++) {
                    System.out.print(buffer[i] + " ");
                }
                System.out.println();
                
                // 将接收到的数据报返回给服务器
                receiver.send(dgram);
            }
        } catch (IOException ex) {
            System.out.println("IOException: " + ex);
        }
  }
  public void pauseApp() {
  }
  public void destroyApp(boolean unconditional) {
  }  
}