Tag: DatagramConnection

/*** Chapter 5 Sample Code for Datagram functionality ***/

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.io.*;
import java.util.*;

public class DatagramTest extends MIDlet {

  // Port 9001 is used for datagram communication
    static final int receiveport  = 9001;
  Receive receiveThread = new Receive();

    public DatagramTest() {
  }

    public void startApp() {
        // Start the listening thread
        receiveThread.start();
        // Send message Hello World!
        sendMessage(“Hello World!”);
    }

    public void pauseApp() {
    }

    public void destroyApp(boolean unconditional)  {
    }

  // This function sends a datagram message on port 9001.
    void sendMessage(String msg)  {
    String destAddr = “datagram://localhost:” + receiveport;
        DatagramConnection dc = null;
    Datagram dgram;
    byte[] bMsg = msg.getBytes();

    try {
           dc = (DatagramConnection)Connector.open(destAddr);
      // Create a datagram socket and send
            dgram= dc.newDatagram(bMsg,bMsg.length,destAddr);
            dc.send(dgram);
      System.out.println(“Sending Packet:” +  msg);
            dc.close();
        }
        catch (Exception e)  {
            System.out.println(“Exception Connecting: ” + e.getMessage());
    }
    finally {
            if (dc != null) {
                try {
                    dc.close();
                }
                catch (Exception e) {
                   System.out.println(“Exception Closing: ” + e.getMessage());
                }
            }
        }
    }

  // This function is a listener. It waits to receive datagram packets on 9001 port
    class Receive extends Thread  {
        public void run() {
        doReceive();
        }

        void doReceive() {
            DatagramConnection dc = null;
            Datagram dgram;
      try {
        // Open Server side datagram connection
                dc = (DatagramConnection)Connector.open(“datagram://:”+receiveport);
          String receivedMsg;
          while (true) {
                    dgram = dc.newDatagram(dc.getMaximumLength());
                try {
             dc.receive(dgram);
          } catch (Exception e) {
            System.out.println(“Exception in receiving message:” + e.getMessage());
          }
                    receivedMsg = new String(dgram.getData(), 0,dgram.getLength());
                    System.out.println(“Received Message: ” + receivedMsg);
                    try {
                       Thread.sleep(500);
                    }
                    catch (Exception e) {
                      System.out.println(“Exception doReceive(): ” + e.getMessage());
                    }
                }

            }
          catch (Exception e) {
          System.out.println(“Exception doReceive(): ” + e.getMessage());
       }
       finally {
          if (dc != null) {
          try {
                       dc.close();
                   }
                   catch (Exception e) {
                      System.out.println(“Exception Closing: ” + e.getMessage());
                   }
               }
          }

        }
     }
 }