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你可以将多个MIDIet程序存储在一个JAR文件中。设备会自动显示一个MIDIet的菜单，又用户选择运行哪个MIDIet程序。
以下的例子中包含所有你所需要的： 两个简单MIDIet程序的源代码，一个存储在JAR文件中的表单文件（MANIFEST），一个JAVA文件描述符文件（.jad），MIDIet的图象文件（.png），还有一个用于运行MIDIet程序和编译，预检，创建JAR文件的DOS批处理文件。
源代码1：
/*----------------------------------------------------
* www.CoreJ2ME.com
*
* Simple MIDlet1
*---------------------------------------------------*/
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
public class MIDlet1 extends MIDlet implements CommandListener
{
private Display display; // Reference to Display object
private TextBox tbxMain; // A Textbox to display a message
private Command cmdExit; // A Command to exit the MIDlet
// The constructor
public MIDlet1()
{
display = Display.getDisplay(this);
cmdExit = new Command("Exit", Command.SCREEN, 1);
tbxMain = new TextBox("Welcome", "Core J2ME", 50, 0);
tbxMain.addCommand(cmdExit);
tbxMain.setCommandListener(this);
}
// Called by application manager to start the MIDlet.
public void startApp()
{
display.setCurrent(tbxMain);
}
// A required method
public void pauseApp()
{ }
// A required method
public void destroyApp(boolean unconditional)
{ }
// Check to see if our Exit command was selected
public void commandAction(Command c, Displayable s)
{
if (c == cmdExit)
{
destroyApp(false);
notifyDestroyed();
}
}
}
源代码2：
/*----------------------------------------------------
* www.CoreJ2ME.com
*
* Simple MIDlet2
*---------------------------------------------------*/
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
public class MIDlet2 extends MIDlet implements CommandListener
{
private Display display; // Reference to Display object
private Form frmMain; // The main form
private TextField txfName; // A text field to prompt for name
private Command cmdExit; // A Command to exit the MIDlet
// The constructor
public MIDlet2()
{
display = Display.getDisplay(this);
cmdExit = new Command("Exit", Command.SCREEN, 1);
txfName = new TextField("Name:", "", 10, TextField.ANY);
frmMain = new Form("Sample Form");
frmMain.addCommand(cmdExit);
frmMain.append(txfName);
frmMain.setCommandListener(this);
}
// Called by application manager to start the MIDlet.
public void startApp()
{
display.setCurrent(frmMain);
}
// A required method
public void pauseApp()
{ }
// A required method
public void destroyApp(boolean unconditional)
{ }
// Check to see if our Exit command was selected
public void commandAction(Command c, Displayable s)
{
if (c == cmdExit)
{
destroyApp(false);
notifyDestroyed();
}
}
}
-----------------------------------------------------------------------------------------------------------------------
mainfest.mf 文件（要存到JAR文件里）：
MIDlet-Name: TwoMIDlets
MIDlet-Version: 1.0
MIDlet-Vendor: Core J2ME Technology
MIDlet-1: MIDlet1,/image1.png, MIDlet1
MIDlet-2: MIDlet2,/image2.png, MIDlet2
MicroEdition-Configuration: CLDC-1.0
MicroEdition-Profile: MIDP-1.0
----------------------------------------------------------------------------------------------------------------------
MIDlet.jad 文件
MIDlet-Name: TwoMIDlets
MIDlet-Version: 1.0
MIDlet-Vendor: Core J2ME Technology
MIDlet-Description: Packaging multiple MIDlets
MIDlet-Jar-URL: MIDlet.jar
MIDlet-Jar-Size: 3144
MIDlet-1: MIDlet1,/image1.png, MIDlet1
MIDlet-2: MIDlet2,/image2.png, MIDlet2
----------------------------------------------------------------------------------------------------------------------
Emulator的显示结果：
从左向右：
1。显示MIDIet程序的菜单。
2。运行MIDIet 1
3。运行MIDIet 2
文章要点：
1． 入口：
MIDlet-1: MIDlet1,/image1.png, MIDlet1
MIDlet-2: MIDlet2,/image2.png, MIDlet2
以上在mainfest和 jad文件中必须是同样的！
2． 你可以省略对图像文件的引用，如下所示：
MIDlet-1: MIDlet1,, MIDlet1
MIDlet-2: MIDlet2,, MIDlet2
3． 下面的属性在jad文件中是可选的：
MIDlet-Description: Packaging multiple MIDlets
4． 以上的例程基于MIDP与 CLDC的1.0.3版本。
-----------------------------------------------------------------------------------------------------------------------------
源代码下载：
下载
关于翻译作者:
bruceyuki,JAVA C#技术爱好者，现就读于新西兰奥克兰大学，正参与大学的一个AI项目,可以点击http://www.matrix.org.cn/user_view.asp?username=bruceyuki查看他的个人信息
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