keycodemidlet.java

Java ME手机应用开发大全一书的配套光盘上的源码

import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
import javax.microedition.midlet.MIDletStateChangeException;
public class KeyCodeMIDlet extends MIDlet
{
    private Display display;
    private KeyCanvas keyCanvas;

    protected void startApp() throws MIDletStateChangeException
    {
		//获取MIDlet的Display对象实例
        display = Display.getDisplay(this);
        keyCanvas = new KeyCanvas();
        display.setCurrent(keyCanvas);

    }

    protected void pauseApp()
    {
    }

    protected void destroyApp(boolean arg0) throws MIDletStateChangeException
    {
    }
	public class KeyCanvas extends Canvas implements CommandListener
{   
    //声明初始化显示的字符串
    private String key = "Press any key";
    protected void paint(Graphics g)
    {
		//填充整个屏幕区域
        g.setColor(255, 255, 255);
        g.fillRect(0, 0, getWidth(), getHeight());
		//更换画笔颜色为黑色
		g.setColor(0, 0, 0);
		//将按键信息在屏幕中绘制出来
        g.drawString(key, getWidth()/2, getHeight()/2, Graphics.TOP|Graphics.HCENTER);

    }
    //当按键按下时调用
    public void keyPressed(int keyCode)
    {
        key = keyCode + " is pressed";
        repaint();
    }
    //当按键释放时调用
    public void keyReleased(int keyCode)
    {
        key = keyCode + " is released";
        repaint();
    }

  
    public void commandAction(Command arg0, Displayable arg1)
    {

    }

 }
}