MIDP图形设计4

　　3、TicTacToeMIDlet.java

　　TicTacToeMIDlet非常简单：它处理MIDlet的生命周期事件。它根据需要创建屏幕对象并且处理来自屏幕的回调。ChoosePieceScreenDone回调被用来创建GameScreen。quit方法则被GameScreen用来结束游戏。

package example.tictactoe;
import java.io.IOException;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.io.*;
public class TicTacToeMIDlet extends MIDlet {
private ChoosePieceScreen choosePieceScreen;
private GameScreen gameScreen;
public TicTacToeMIDlet()
{
}
public void startApp() {
Displayable current = Display.getDisplay(this).getCurrent();
if (current == null) {
// first time we've been called
// Get the logo image
Image logo = null;
try
{
logo = Image.createImage("/tictactoe.png");
}
catch (IOException e) {
// just use null image
}
Alert splashScreen = new Alert(null, "Tic-Tac-Toe\nForum Nokia", logo, AlertType.INFO);


splashScreen.setTimeout(4000);
// 4 seconds
choosePieceScreen = new ChoosePieceScreen(this);
Display.getDisplay(this).setCurrent(splashScreen, choosePieceScreen);
}
else
{
Display.getDisplay(this).setCurrent(current);
}
}
public void pauseApp() {
}
public void destroyApp(boolean unconditional) {
}
public void quit()
{
destroyApp(false);
notifyDestroyed();
}
public void choosePieceScreenDone(boolean isPlayerCircle)
{
gameScreen = new GameScreen(this, isPlayerCircle);
Display.getDisplay(this).setCurrent(gameScreen);
}
}

　　4、ChoosePieceScreen.java

　　ChoosePieceScreen是一个基于高级应用编程接口窗体的屏幕，允许游戏者选择圆或叉作为棋子。当游戏者按下OK键时，它使用MIDlet的回调方法choosePieceScreenDone来处理游戏者的选择。

package example.tictactoe;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.io.*;
public class ChoosePieceScreen extends List implements CommandListener
{
private static final String CIRCLE_TEXT = "Circle";
private static final String CROSS_TEXT = "Cross";
private final TicTacToeMIDlet midlet;
private final Command quitCommand;
public ChoosePieceScreen(TicTacToeMIDlet midlet) {
super("Choose your piece", List.IMPLICIT);
this.midlet = midlet;
append(CIRCLE_TEXT, loadImage("/circle.png"));
append(CROSS_TEXT, loadImage("/cross.png"));
quitCommand = new Command("Quit", Command.EXIT, 2);
addCommand(quitCommand);
setCommandListener(this);
}
public void commandAction(Command c, Displayable d) {
boolean isPlayerCircle = getString(getSelectedIndex()).equals(CIRCLE_TEXT);
if (c == List.SELECT_COMMAND) {
midlet.choosePieceScreenDone(isPlayerCircle);
}
else
// quit Command
{
midlet.quit();
}
}
private Image loadImage(String imageFile)
{
Image image = null;
try

{
image = Image.createImage(imageFile);
}
catch (Exception e)
{
// Use a 'null' image in the choice list (i.e. text only choices).
}
return image;
}
}

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