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封裝多MIDIet程序

編輯：J2ME

你可以將多個MIDIEt程序存儲在一個JAR文件中。設備會主動顯示一個MIDIet的菜單，又用戶選擇運行哪個MIDIEt程序。

　　以下的例子中包含所有你所需要的：兩個簡略MIDIEt程序的源代碼，一個存儲在JAR文件中的表單文件（MANIFEST），一個Java文件描寫符文件（.jad），MIDIet的圖象文件（.png），還有一個用於運行MIDIEt程序和編譯，預檢，創立JAR文件的DOS批處理文件。
　

源代碼1：

/*----------------------------------------------------
* 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();
  }
}
}

源代碼2：

/*----------------------------------------------------
* 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文件裡）：

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的顯示成果：

　　從左向右：

　　1、顯示MIDIEt程序的菜單。

　　2、運行MIDIEt 1

　　3、運行MIDIEt 2

　　文章要點：

　　1．進口：

MIDlet-1: MIDlet1,/image1.png, MIDlet1
MIDlet-2: MIDlet2,/image2.png, MIDlet2

　　以上在mainfest和 jad文件中必需是同樣的！

　　2．你可以省略對圖像文件的引用，如下所示：

MIDlet-1: MIDlet1,, MIDlet1
MIDlet-2: MIDlet2,, MIDlet2

　　3．下面的屬性在jad文件中是可選的：