maze.java

一个基于j2me MIDP的迷宫游戏

/*
 * Maze.java
 *
 * Created on 2005年12月2日, 下午1:04
 */

package com.j2medev.maze;

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

/**
 * This is the main class of the maze game.
 *
 * @author Carol Hamer
 */
public class Maze extends MIDlet implements CommandListener {
    
    //----------------------------------------------------------------
    //  game object fields
    
    /**
     * The canvas that the maze is drawn on.
     */
    private MazeCanvas myCanvas;
    
    /**
     * The screen that allows the user to alter the size parameters
     * of the maze.
     */
    private SelectScreen mySelectScreen;
    
    //----------------------------------------------------------------
    //  command fields
    
    /**
     * The button to exit the game.
     */
    private Command myExitCommand = new Command("Exit", Command.EXIT, 99);
    
    /**
     * The command to create a new maze.  (This command may appear in a menu)
     */
    private Command myNewCommand = new Command("New Maze", Command.SCREEN, 1);
    
    /**
     * The command to dismiss an alert error message.  In MIDP 2.0
     * an Alert set to Alert.FOREVER automatically has a default
     * dismiss command.  This program does not use it in order to
     * allow backwards com
     */
    private Command myAlertDoneCommand = new Command("完成", Command.EXIT, 1);
    
    /**
     * The command to go to the screen that allows the user
     * to alter the size parameters.  (This command may appear in a menu)
     */
    private Command myPrefsCommand
            = new Command("迷宫规模设置", Command.SCREEN, 1);
    
    //----------------------------------------------------------------
    //  initialization
    
    /**
     * Initialize the canvas and the commands.
     */
    public Maze() {
        try {     myCanvas = new MazeCanvas(Display.getDisplay(this));
        myCanvas.addCommand(myExitCommand);
        myCanvas.addCommand(myNewCommand);
        myCanvas.addCommand(myPrefsCommand);
        myCanvas.setCommandListener(this);
        } catch(Exception e) {
            // if there's an error during creation, display it as an alert.
            Alert errorAlert = new Alert("error",
                    e.getMessage(), null, AlertType.ERROR);
            errorAlert.setCommandListener(this);
            errorAlert.setTimeout(Alert.FOREVER);
            errorAlert.addCommand(myAlertDoneCommand);
            Display.getDisplay(this).setCurrent(errorAlert);
        }
    }
    
    //----------------------------------------------------------------
    //  implementation of MIDlet
    
    /**
     * Start the application.
     */
    public void startApp() throws MIDletStateChangeException {
        if(myCanvas != null) {
            myCanvas.start();
        }
    }
    /**
     * Clean up.
     */
    public void destroyApp(boolean unconditional)
    throws MIDletStateChangeException {
        myCanvas = null;
        System.gc();
    }
    
    /**
     * Does nothing since this program occupies no shared resources
     * and little memory.
     */
    public void pauseApp() {
    }
    
    //----------------------------------------------------------------
    //  implementation of CommandListener
    
  /*
   * Respond to a command issued on the Canvas.
   * (reset, exit, or change size prefs).
   */
    public void commandAction(Command c, Displayable s) {
        if(c == myNewCommand) {
            myCanvas.newMaze();
        } else if(c == myAlertDoneCommand) {
            try {
                destroyApp(false);
                notifyDestroyed();
            } catch (MIDletStateChangeException ex) {
            }
        } else if(c == myPrefsCommand) {
            if(mySelectScreen == null) {
                mySelectScreen = new SelectScreen(myCanvas);
            }
            Display.getDisplay(this).setCurrent(mySelectScreen);
        } else if(c == myExitCommand) {
            try {
                destroyApp(false);
                notifyDestroyed();
            } catch (MIDletStateChangeException ex) {
            }
        }
    }
}