JDBC comes to J2ME finally?

Content
Step 1:Install Java Step 2:Install J2ME Toolkit Step 3:Testing

Installing JDK ...

Firstly, goto "http://java.sun.com" and grab a copy of the latest JDK (notice: only J2RE will only allow you to run java apps, if you are going to developement MUST use a JDK).
Unzip it and put it in a folder, here we use "c:/java/j2sdk" as a default directory!
Then you have to setup an environment variable in order to make work.

Setting up environment variable for Java ...

Right click on "My Computer", select "properties"->"Advanced"->"Environment Variables", and you will see stuff like below:JAVA_HOME=C:\java\jdk1.2.4_01 (refer to path where you install the Java sdk)

PATH= ... ;C:\java\jdk1.2.4_01\bin

Installing J2ME Toolkit ...

This may be as simple as it seems, just goto j2me download site, pick a copy of " Sun Java Wireless Toolkit" ... install it and start coding. Note that you may have a few choice either using an IDE like NetBean, JBuilder, and so on; to the build-in code writing module with the WirelessToolkit that you just downloaded or even start off with a Notepad!

Well my personal favor, a Notepad will do, try compiling with command prompt also, had a better feel of the whole development process.

Testing ...

Kick Start

Six simple Steps for writing a J2ME:

1. Code a Java file.
2. Compile with CLDC and MIDP library.
3. Preverify it with "preverify.exe".
4. Write a manifest file, then package it with every classes and resources in a JAR file.
5. Write a JAD file for deploying purposes.
6. Test it on emulator or real device, do some performance tweaking and fine tuning for portability.

Some assumption:
• %J2ME_HOME%=C:\WTK22\
• %JAVA_HOME%=C:\Program Files\Java\jdk1.5.0_04

Writing a simple CLDC app...

import java.io.*; import javax.microedition.io.*; public class TestInputOutput { public static void main( String[] args ){ try { String uri ="socket://www.ericgiguere.com:80"; StreamConnection conn = (StreamConnection) Connector.open( uri ); // Send HTTP request... PrintStream out = new PrintStream(conn.openOutputStream() ); out.println( "GET /index.html HTTP/0.9\r\n" ); out.flush(); // Get raw HTTP reply... InputStream in = conn.openInputStream(); int ch; while( ( ch = in.read() ) != -1 ){ System.out.print( (char) ch ); } in.close(); out.close(); conn.close(); } catch( ConnectionNotFoundException e ){ System.out.println( "Socket could not be opened" ); } catch( IOException e ){ System.out.println( e.toString() ); } System.exit( 0 ); } }

Writing a simple MIDP app...

import javax.microedition.lcdui.*; import javax.microedition.midlet.*; public class HelloMIDlet extends MIDlet implements CommandListener { private Form mMainForm; public HelloMIDlet() { mMainForm = new Form("HelloMIDlet"); mMainForm.append(new StringItem(null, "Hello, MIDP!")); mMainForm.addCommand(new Command("Exit", Command.EXIT, 0)); mMainForm.setCommandListener(this); } public void startApp() { Display.getDisplay(this).setCurrent(mMainForm); } public void pauseApp() {} public void destroyApp(boolean unconditional) {} public void commandAction(Command c, Displayable s) { notifyDestroyed(); } }

To Compile your codes:

%JAVA_HOME%\bin\javac -bootclasspath %J2ME_HOME%\lib\midpapi20.jar;%J2ME_HOME%\lib\cldcapi.jar MyJ2MEApp.java

To Preverify your class:

%J2ME_HOME%\bin\preverify.exe -classpath %J2ME_HOME%\lib\midpapi20.jar;%J2ME_HOME%\lib\cldcapi.jar MyJ2MEApp

Writing a Menifest file:

MIDlet-Name: MyJ2MEApp MIDlet-Version: 1.0.0 MIDlet-Vendor: Avatar

To Package everything:

%JAVA_HOME%\bin\jar cvfm MyJ2MEApp.jar Manifest.mf MyJ2MEApp.class

Writing a Java Application Describtion (JAD) file:

MIDlet-1: MyJ2MEApp, , MyJ2MEApp MIDlet-Name: MyJ2MEApp MIDlet-Version: 1.0.0 MIDlet-Vendor: Avatar MIDlet-Jar-URL: MyJ2MEApp.jar MIDlet-Jar-Size: MicroEdition-Profile: MIDP-2.0 MicroEdition-Configuration: CLDC-1.1

*Important notes - remember to fill in the MIDlet-Jar-Size with a correct file size of your jar (e.g.:MIDlet-Jar-Size: 1469)*
To Test your application:

%J2ME_HOME%\bin\emulator.exe -Xdescriptor MyJ2MEApp.jad

Hooray, it is working!!!

Resources:

1. Tutorial from java.net.
2. Sample code from sun developer.