socketconnection.java

J2ME code to connect socket to remote server at port 80 and request HTTP service for viewing index.

// SocketConnection.java 
// Connect socket to remote server at port 80
// and request HTTP service for viewing index.html 

// initiate MIDlet Class
import javax.microedition.midlet.*;

// initiate GUI Class
import javax.microedition.lcdui.*;

// initiate Network Class
import javax.microedition.io.*;

// initiate IO Class
import java.io.*;

// create SocketConnection by inheritting MIDlet
public class SocketConnection extends MIDlet 
{
    // declare object variable sc for i/p stream
	// and o/p for send/receive socket connection
    private StreamConnection sc = null;
    
	// declare object variable os for o/p stream
	// use for service requesting
    private OutputStream os = null;

	// declare object variable dos for o/p stream data
	// use for service requesting
    private DataOutputStream dos = null;
    
	// declare object is for i/p stream
	// use for web server responding
    private InputStream is = null;

	// declare object dis for i/p stream data
	// use for web server responding
    private DataInputStream dis = null;
    
	// create connection string to host 216.21.156.11
	// at port 80 by socket connection
    private String url = "socket://216.21.156.11:80";
    
	// declare object variable buffer 
	// for containing web pag content
    private StringBuffer buffer;
    
    // declare variables for GUI components
    private Display display = null;
    private Form screen;
    private StringItem getString;
    
	// initiate SocketConnection() Constructor 
	// for the MIDlet 
    public SocketConnection() 
	{
        // create object buffer for carrying string
	// for service requsting
        buffer = new StringBuffer();

		// get object display 
		// for mobile device display
        display = Display.getDisplay(this);

		// create object screen 
		// for forming Page Content on the screen
        screen = new Form("Page Content");
    }
    
	// start MIDlet 
    public void startApp() 
	{
        try {
			// create object sc 
			// for socket connection
            sc = (StreamConnection) Connector.open(url);

			// create object os 
			// for o/p stream
            os = sc.openOutputStream();
		
			// create object dos
			// for o/p stream data
            dos = new DataOutputStream(os);
            
			// request HTTP service
            dos.writeChars("GET /toc.htm \n");

			// use method flush() 
			// to make sure that the request has 			// been sent to server	
            dos.flush();
            
			// create object is 
			// for i/p stream
            is = sc.openInputStream();

			// create object dis 
			// for o/p stream data
            dis = new DataInputStream(is);

            int inputChar;
			// read the web page content
			// until it ends
            while ( (inputChar = dis.read()) != -1) 
			{
			// use buffer 
                buffer.append((char) inputChar);
            }

			// convert web page content
			// to string by using getString
            getString = new StringItem(null, buffer.toString());

			// form string on mobile device
            screen.append(getString);

			// display string on screen
            display.setCurrent(screen);
            
        } 
		catch (IOException ioe) {
			// report error 
            System.out.println(ioe.getMessage());
        } 
		finally {
            try {
			// close I/O stream
                if (dis != null)
                    dis.close();
            } 
			catch (Exception ex) {}
            try {
			// close I/O stream
                if (dos != null)
                    dos.close();
            } 
			catch (Exception ex) {}
            try {
			// close o/p stream
                if (os != null)
                    os.close();
            } 
			catch (Exception ex) {}
            try {
			// close i/p stream
                if (is != null)
                    is.close();
            } 
			catch (Exception ex) {}
            try {
			// close stream connection
                if (sc != null)
                    sc.close();
            } 
			catch (Exception ex) {}
        }
    }
    
	// pause MIDlet
    public void pauseApp() 
	{ }
    
	// release all MIDlet resources 
    public void destroyApp(boolean unconditional) 
	{
        // clear objects value
        buffer = null;
        display = null;
        screen = null;
        getString = null;
    }
}