Friday, September 12, 2003

J2SE: A nice tool to learn API differences

JDiff is a Javadoc doclet which generates an HTML report of all the packages, classes, constructors, methods, and fields which have been removed, added or changed in any way, including their documentation, when two APIs are compared. This is very useful for describing exactly what has changed between two releases of a product. Only the API (Application Programming Interface) of each version is compared. It does not compare what the source code does when executed.

Sample Reports:
Comparing J2SE1.4.0 and J2SE1.4.1
Comparing J2SE1.3.1 and J2SE1.4

Posted by Kumar at 11:22 AM 0 comments

Tuesday, September 09, 2003

J2ME: Turning your phone into web Server.

I wrote a simple midlet which turns my Phone into simple web server. To keep the code simple, I removed the additional GPS capabilities. Currently the web server listens to port 8000 and repsonds "Hello, I am Kumar Mettu's Phone. Thanks for Visiting" for all requests that are sent to this tiny web server. Note that this code is tested only on Motorola i88s with Nextel Total Connect Service.

Here is the code for the tiny web server:




001 import java.io.IOException;
002 import java.io.InputStream;
003 import java.io.PrintStream;
004 
005 import javax.microedition.io.Connector;
006 import javax.microedition.io.StreamConnection;
007 import javax.microedition.io.StreamConnectionNotifier;
008 import javax.microedition.lcdui.Display;
009 import javax.microedition.midlet.MIDlet;
010 
011 /**
012  * MIDlet working as simple personal WebServer.
013  * Currently this serves simple HTTP GET operation.
014  *
015  * @author Kumar Mettu
016  * @version 0.61
017  */
018 
019 public class WebServer extends MIDlet {
020 
021     private Display display;
022 
023     StreamConnectionNotifier scn = null;
024 
025     /**
026      * Default constructor.
027      */
028     public WebServer() {
029        display = Display.getDisplay(this);
030     }
031 
032     /**
033      * This will be invoked when we start the MIDlet
034      */
035     public void startApp() {
036         try {
037             scn =(StreamConnectionNotifier)Connector.open("serversocket://:8000");
038             while (true) {
039                 StreamConnection sc = (StreamConnection)scn.acceptAndOpen();
040 
041                 // service the connection in a separate thread
042                 Connection c = new Connection(sc);
043                 c.start();
044             }
045 
046 
047         } catch (IOException e) {
048             //Handle Exceptions any other way you like.
049             //No-op
050         }
051     }
052 
053     /**
054      * Pause, discontinue ....
055      */
056     public void pauseApp() {
057         try {
058             if (scn != null)
059                 scn.close();
060         } catch(Exception e) {
061         }
062 
063     }
064 
065     /**
066      * Destroy. Cleanup everything.
067      */
068     public void destroyApp(boolean unconditional) {
069         try {
070             if (scn != null)
071                 scn.close();
072         } catch(Exception e) {
073         }
074     }
075 
076     /**
077      * Thread to handle client request.
078      */
079     class Connection extends Thread
080     {
081 
082         public Connection(StreamConnection c) {
083             client = c;
084         }
085 
086         /**
087          * Handles client request.
088          */
089         public void run() {
090             InputStream s = null;
091             PrintStream out = null;
092             StringBuffer b = new StringBuffer();
093             try {
094 
095                 s = client.openInputStream();
096 
097                  //Ignore reading request to reduce the amount of data
098                  //transfered to Phone.
099                 /*int ch;
100                 while((ch = s.read()) != -1) {
101                     b.append((char) ch);
102                 }
103                 System.out.println(b.toString());*/
104 
105                 out = new PrintStream(client.openOutputStream());
106                 String response =
107                              "<HTML>"+
108                              "<HEAD>"+
109                                 "<TITLE>Kumar's Location</TITLE>"+
110                              "</HEAD>"+
111                              "<BODY>Hello, I am Kumar Mettu's Phone. "+
112                                      "Thanks for Visiting.</BODY>"+
113                              "</HTML>";
114                 out.println("HTTP/1.0 200 OK\n");
115                 out.println(response);
116 
117             }
118             catch (Throwable ioe) {
119                 //Handle Exceptions any other way you like.
120                 //No-op
121             }
122             finally {
123                 try {
124                     if (s != null)
125                         s.close();
126                     if (out != null)
127                         out.close();
128                     if (client != null)
129                         client.close();
130                 }
131                 catch (IOException ioee) {
132           //Handle Exceptions any other way you like.
133           //No-op
134                 }
135             }
136         }
137 
138         private StreamConnection client;
139     }
140 
141 }
142   


I know there is no business value for this web server. But hey turning phone into a web server and viewing it serve web pages to browser is fun :-)

Posted by Kumar at 11:47 PM 8 comments

J2ME: My new J2ME-GPS phone

Since my old phone is more than 2 years old, I bought a new Motorola i88s phone which has J2ME and GPS support.
I added some cool J2ME applications which will probably be blogging about in coming days.

Posted by Kumar at 11:31 PM 0 comments

Monday, September 08, 2003

Molecular Expressions: Science, Optics and You - Powers Of 10: Interactive Java Tutorial

Molecular Expressions: Science, Optics and You - Powers Of 10: Interactive Java Tutorial: "View the Milky Way at 10 million light years from the Earth. Then move through space towards the Earth in successive orders of magnitude until you reach a tall oak tree just outside the buildings of the National High Magnetic Field Laboratory in Tallahassee, Florida. After that, begin to move from the actual size of a leaf into a microscopic world that reveals leaf cell walls, the cell nucleus, chromatin, DNA and finally, into the subatomic universe of electrons and protons."

Posted by Kumar at 8:21 AM 0 comments

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