将MIDlet和界面别离[Java编程]

固然利用面向对象的思惟举行J2ME的编程,会增添代码量(增添公布文件的大小)和提高代码的复杂性.但是为了代码的可保护性和可扩大性,目前绝大大都的程序还是将界面和逻辑别脱离来,下面先阐明一下若何将MIDlet主类和界面别离.

在界面和MIDlet中,需求交换的系统内容主要有两部份:1、Display对象;2、MIDlet中的退出处理.

示例代码以下:

package testmidlet;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
public class TestMIDlet extends MIDlet {
private static TestMIDlet instance;
private LoginForm displayable ;
private Display display;
/** Constructor */
public TestMIDlet() {
instance = this;
display = Display.getDisplay(this);
displayable= new LoginForm(display);
}
/** Main method */
public void startApp() {
display .setCurrent(displayable);
}
/** Handle pausing the MIDlet */
public void pauseApp() {
}
/** Handle destroying the MIDlet */
public void destroyApp(boolean unconditional) {
}
/** Quit the MIDlet */
public static void quitApp() {
instance.destroyApp(true);
instance.notifyDestroyed();
instance = null;
}
}
package testmidlet;
import javax.microedition.lcdui.*;
public class LoginForm extends Form implements CommandListener {　　private Display display;
/** Constructor */
public LoginForm(Display display) {
super("Test");　　this.display = display;
setCommandListener(this);
// add the Exit command
addCommand(new Command("Exit", Command.EXIT, 1));
}
/**Handle command events*/
public void commandAction(Command command, Displayable displayable) {
/** @todo Add command handling code */
if (command.getCommandType() == Command.EXIT) {
// stop the MIDlet
TestMIDlet.quitApp();
}
}
}

此中display对象可以通过构造办法举行传送,退出办法可以通过办法调用来履行.这样,你的代码就可以实现MIDlet类和界面别离了.