Developing J2ME Applications.ppt

1、Developing J2ME Applications,Mobile and Wireless Networks,J2ME Architecture,Layers consisting of Profiles Configurations Virtual Machines Host Operating System,J2ME Architecture,Configurations They define the minimum Java platform for a set of common devices Support one or more profiles Horizontal i

2、n nature Defined through Java Community Process (JCP) Must go through compatibility tests Profiles Supplement the configuration to provide capabilities for a specific family of devices or specific industry segment Provide flexibility while optimizing portability Often provide UI, event handling, per

3、sistence mechanisms, etc. Defined through JCP Must go through compatibility tests,J2ME Architecture,J2ME Architecture,J2ME Configurations Connected Device Configuration (CDC) Connected Limited Device Configuration (CLD) Two design CDC = things you plug into the wall CLDC = things you hold in your ha

4、nd CLDC-Based Profiles Mobile Information Device Profile (MIDP) Support for cell phones and pagers,The J2ME Universe Today,Creating J2ME Applications,Identify the devices Identify the profiles supported by devices Develop the Application Using the MID profile, the application will target cell phones

5、 and pagers Write an application that displays the String “Hello, Small World!” Requires the environment; MIDP reference implementation http:/ Will run in the MIDP emulator,Tour of CLDC/MIDP,Packages Javax.microedition.io Javax.microedition.lcdui Javax.microedition.midlet Javax.microedtion.rms Conta

6、ins user interface widgets Form, TextField, TextBox, DateField, List, Image, Gauge, Alert, Canvas, Graphics, Display Event handling classes Command and CommandListener Two APIs, high and low High level for GUI widgets, scrolling, etc. Low level for graphics and fine-grained UI control,Developing J2M

7、E Wireless Applications,Use ktoolbar to create a project Configure the Midlet Build and Run the project MIDlet class, the application-level class Abstract, need to define methods startApp() pauseApp() destroyApp(boolean unconditional),Sample Code,import javax.microedition.lcdui.*; import javax.microedition.midlet.*;public class HiMIDlet extends MIDlet private TextBox textbox;public HiMIDlet() textbox = new TextBox (“, “Hello World!“, 20, 0);public void startApp() Display.getDisplay(this).setCurrent(textbox);public void pauseApp() public void destroyApp(boolean unconditional) ,