Demonstrates the functionality of DatagramConnection framework.
/*** 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()); } } } } } }