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标题: 利用MIDP API建立跨多种无线平台的应用02 [打印本页]

作者: samwalton 时间: 2014-3-25 20:28 标题: 利用MIDP API建立跨多种无线平台的应用02

一个简单的例子

　　以下是一个HellwoWorld类型的简单例子，它可让你看看一个midlet的生命周期，midlet是在你的移动设备上执行的代码名字。它与一个applet类似，它包含有用户界面、数据和控制能力。

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

public class HelloMidlet extends MIDlet implements CommandListener
{
　// Initialize the Midlet Display variable
　private Display midletDisplay;

　// Initialize a variable for the doneCommand
　private Command doneCommand;

　public HelloMidlet()
　{
　// Retrieve the display from the static display object
　midletDisplay = Display.getDisplay(this);

　// Initialize the doneCommand
　doneCommand = new Command("DONE", Command.SCREEN, 1);
}

/**
* Create the Hello Midlet World TextBox and associate
* the exit command and listener.
*/
public void startApp()
{
// Create the TextBox containing the "Hello Midlet World!!" message
TextBox textBox = new TextBox("Hello Midlet", "Hello Midlet World!!", 256, 0);

// Add the done Command to the TextBox
textBox.addCommand(doneCommand);

// Set the command listener for the textbox to the current midlet
textBox.setCommandListener( (CommandListener) this);

// Set the current display of the midlet to the textBox screen
midletDisplay.setCurrent(textBox);
}

/**
* PauseApp is used to suspend background activities and release
* resources on the device when the midlet is not active.
*/
public void pauseApp()
{
}

/**
* DestroyApp is used to stop background activities and release
* resources on the device when the midlet is at the end of its
* life cycle.
*/
public void destroyApp(boolean unconditional)
{
}

/*
* The commandAction method is implemented by this midlet to
* satisfy the CommandListener interface and handle the done action.
*/
public void commandAction(Command command, Displayable screen)
{
// If the command is the doneCommand
if (command == doneCommand)
{
// Call the destroyApp method
destroyApp(false);

// Notify the midlet platform that the midlet has completed
notifyDestroyed();
}
}
}

midlet的输出如图一所示，它其实是J2ME Windows Toolkit DefaultGrayPhone模拟器的一张抓图。

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