menu.java

J2ME做的打砖块游戏,是学校的课程项目

import javax.microedition.lcdui.Canvas;
import javax.microedition.midlet.MIDlet;

public class Menu {
    private Main midlet;
    private Engine engine;
    private EngineState state;
    private AbstractMenu menu;
    private MainMenu mainMenu;
    private LevelMenu levelMenu;
    private boolean stepEnabled = true;

    
    public Menu() {
        mainMenu = new MainMenu();
        levelMenu = new LevelMenu();
        menu = mainMenu;
        state = new EngineState();
    }

    public int getSelected() {
        return menu.getSelected();
    }

    public void keyPressed(int keycode) {
        menu.keyPressed(keycode);
    }

    public MenuItem[] getItems() {
        return menu.getItems();
    }

    public void setMIDlet(MIDlet midlet) {
        this.midlet = (Main) midlet;
    }

    public void setEngine(Engine engine) {
        this.engine = engine;
        engine.getState(state);
    }

    public void showResumeItem(boolean show) {
        mainMenu.showResumeItem(show);
    }

    public void resetSelected() {
        menu.resetSelected();
    }

    private abstract class AbstractMenu {
        protected MenuItem back = new MenuItem("Back", true);
        protected MenuItem[] items;
        private int selected = 0;

        public void keyPressed(int keycode) {
            if (stepEnabled) {
                if ((keycode == Canvas.UP) && (selected > 0)) {
                    setSelected(-1);
                    return;
                }

                if ((keycode == Canvas.DOWN) && 
                        (selected < (items.length -1))) {
                    setSelected(1);
                    return;
                }
            }

            if (keycode == Canvas.FIRE) {
                executeCommand(selected);
            }            
        }

        public MenuItem[] getItems() {
            return items;
        }

        public int getSelected() {
            return selected;
        }

        private void setSelected(int step) {        
            if (step > 0) {
                selected++;
            } else {
                selected--;
            }
            if (!items[selected].isEnabled()) {
                setSelected(step);
            }        
        }

        protected void resetSelected() {
            selected = 0;
        }

        protected abstract void executeCommand(int selected);
    }

    static class MenuItem {
        private String text;
        private boolean enabled;

        public MenuItem(String text, boolean enabled) {
            this.text = text;
            this.enabled = enabled;
        }

        public String getText() {
            return text;
        }

        public boolean isEnabled() {
            return enabled;
        }

        public void setText(String text) {
            this.text = text;
        }

        public void setEnabled(boolean enabled) {
            this.enabled = enabled;
        }
    }

    private class MainMenu extends AbstractMenu {
        protected static final int ITEM_RESUME = 0;
        protected static final int ITEM_START = 1;
		protected static final int ITEM_DOWNLOADLEVELS = 2;
		protected static final int ITEM_HELP = 3;

        protected static final int ITEM_EXIT = 4;

        protected MenuItem[] mainItems1 = {
            new MenuItem("Start Game", true),
			new MenuItem("Download Levels", true),
			new MenuItem("Game Help", true),
            new MenuItem("Exit", true),
        };

        protected MenuItem[] mainItems2 = {
            new MenuItem("Resume Game", true),
            new MenuItem("Start Game", true),
            new MenuItem("Download Levels", true),
			new MenuItem("Game Help", true),        
            new MenuItem("Exit", true),
        };        

        public MainMenu() {
            items = mainItems1;
        }

        protected void executeCommand(int selected) {
            if ((items == mainItems1)) {
                selected++;
            }

            switch (selected) {
                case ITEM_START:
                    levelMenu.setItems(engine.getAvailableLevels());
                    menu = levelMenu;
                    break;

				case ITEM_DOWNLOADLEVELS:
					engine.currentNum = 0;
					engine.totalNum = 10;
					engine.downloadLevel = true;
					engine.setState(Engine.PROGRESS);
					break;
				case ITEM_HELP:
					engine.setState(Engine.HELP);
					break;
                
                case ITEM_EXIT:
                    engine.stop();
                    midlet.destroyApp(true);
                    break;
                case ITEM_RESUME:
                    engine.setState(Engine.PLAY);
                    engine.resumeGame();
                    midlet.showCommandExit(true);
            }            
        }

        protected void showResumeItem(boolean show) {
            if (show) {
                items = mainItems2;
            } else {
                items = mainItems1;
            }
        }
    }

    private class LevelMenu extends AbstractMenu {
        protected MenuItem[] levelItems;
        protected int levels = 0;

        protected void executeCommand(int selected) {
            if (selected < levels) {
                engine.startGame(selected);
                midlet.showCommandExit(true);
                mainMenu.showResumeItem(true);
            }
            menu = mainMenu;
            resetSelected();
        }

        public void setItems(int levels) {
            this.levels = levels;
            levelItems = new MenuItem[levels + 1];

            for (int i = 0; i < levels; i++) {
                levelItems[i] = new MenuItem("Level " + (i + 1), true);
            }

            levelItems[levels] = back;
            items = levelItems;
        }
    }
	
}