Giving a try to MIDP - Simple example : POP3 connection

Every application that you will be creating must be extending the MIDLet class :

// Handling the screen
import javax.microedition.lcdui.*;
// include MIDlet class libraries
import javax.microedition.midlet.*;
// include networking class libraries
import javax.microedition.io.*;
import java.io.*;

public class testMD extends MIDlet implements CommandListener
{
   // the screen of the device
    private Display mDisplay;
    // the exit button
    private Command exitCmd;
    // Every thing is displayed in a form
    private Form mForm;

    // starting our program
    public void startApp()
    {
                // Creating our form
		if ( mForm == null )
		{
                        // Setting the title
			mForm = new Form( "Welcome to POP3 Sample!" );
			// Creating the button 'EXIT'
			exitCmd = new Command( "Exit", Command.EXIT, 0 );
			// Adding a button command to the form
			mForm.addCommand( exitCmd );
			// This class is responsible for handling the button
			mForm.setCommandListener( this );
			// retrieve the display
			mDisplay = Display.getDisplay( this );
			// Creating our POP3 socket
			SocketExample se = new SocketExample(mDisplay,mForm);
			// Start getting informations from the POP server
			se.start();		
		}
	}

    // Nothing to be done here
    public void pauseApp()
    {
    }
	
    // Nothing to be done here
    public void destroyApp( boolean unconditional )
    {
    }

    // Hnalding the exit button
    public void commandAction( Command c, Displayable s )
    {   
        if ( c == exitCmd )
        {
            // Destroying the app and notification of the destrcution for a clean exit
            destroyApp( true );
            notifyDestroyed();
        }
    }
}

Now let’s have a look to our SocketExample class :

class SocketExample{
	// StreamConnection allows bidirectional communication
	private StreamConnection streamConnection = null;
	
	// use OutputStream to send requests
	private OutputStream outputStream = null;
	private DataOutputStream dataOutputStream = null;
	
	// use InputStream to receive responses from a POP server
	private InputStream inputStream = null;
	private DataInputStream dataInputStream = null;
	
	// specify the connect string
	//private String connectString = "http://213.186.33.19:80";
	
	private String connectString = "socket://213.36.80.100:110";
        // use a StrignBuffer to store the retrieved page contents
	private StringBuffer results;
	
	// define GUI components
	private Display myDisplay = null;
	private Form resultScreen;
	private StringItem resultField;
	
	public SocketExample(Display d,Form f) {
		// initializing GUI display
		results = new StringBuffer();
		myDisplay = d;
		resultScreen = f;
	}
	
	public void start() {
		try {
			// establish a socket connection with remote server
			resultScreen.append(new StringItem(null, "Opening connection"));
			myDisplay.setCurrent(resultScreen);
			streamConnection = (StreamConnection) Connector.open(connectString);
			
			
			// create DataOuputStream on top of the socket connection
			outputStream = streamConnection.openOutputStream();
			dataOutputStream = new DataOutputStream(outputStream);
			
			// create DataInputStream on top of the socket connection
			inputStream = streamConnection.openInputStream();
			dataInputStream = new DataInputStream(inputStream);
			
			resultScreen.append(new StringItem(null, "Read header"));
			myDisplay.setCurrent(resultScreen);
			results = waitHeader();
			
			/* Envoi du HELLO */
			
			results = sendAndWaitReply("USER XXXXXXXXXX\n");
			resultField = new StringItem(null, results.toString());
			resultScreen.append(resultField);
			
			results = sendAndWaitReply("PASS XXXXXXXXXX\n");
			resultField = new StringItem(null, results.toString());
			resultScreen.append(resultField);
	
	
			

			
		} catch (IOException e) {
			resultScreen.append(new StringItem(null, "Erreur!"));
			resultScreen.append(new StringItem(null, e.toString()));
			System.err.println("Exception caught:" + e);
		} finally {
			// free up I/O streams and close the socket connection
			try {
				if (dataInputStream != null)
					dataInputStream.close();
			} catch (Exception ignored) {}
			try {
				if (dataOutputStream != null)
					dataOutputStream.close();
			} catch (Exception ignored) {}
			try {
				if (outputStream != null)
					outputStream.close();
			} catch (Exception ignored) {}
			try {
				if (inputStream != null)
					inputStream.close();
			} catch (Exception ignored) {}
			try {
				if (streamConnection != null)
					streamConnection.close();
			} catch (Exception ignored) {}
		}
	}
	
	public StringBuffer waitHeader(){
		return sendAndWaitReply(null);
	}
	public StringBuffer sendAndWaitReply(String cmd){
		int inputChar;
		try{
			if (cmd != null){
				for (int i = 0 ; i < cmd.length() ; i++){
					dataOutputStream.writeByte(cmd.charAt(i));
				}
				dataOutputStream.flush();
			}
			boolean eol,eos;
			results = new StringBuffer();
			eol = false;eos = false;
			while ( !eol && ! eos){
				inputChar = dataInputStream.read();
				if (inputChar == 10) eol = true;
				if (inputChar == -1) eos = true;
				results.append((char) inputChar);
			}
			return results;
		} catch (Exception ignored) {
			return  null;
		}
	}
}

After compilation here is the result :

Giving a try to MIDP - Simple example : POP3 connection

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