repeateventtest.java

在J2ME游戏中仿真Key Repeat事件, 但对于手机这种小设备来说,连续按键很吃力, 这里提供连续按键的一种方便机制

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

public class RepeatEventTest extends MIDlet implements CommandListener, ItemStateListener{

        Display display;
        MyCanvas myCanvas;
        Form form;
        ChoiceGroup setRepeat;
        Gauge timeInterval;
        Command exitCmd;
        Command okCmd;
        Command backCmd;
        Timer repeatTimer;
        RepeatTask task;
        boolean simRepeat, hasRepeat;

        public RepeatEventTest(){
                display = Display.getDisplay(this);
                exitCmd = new Command("退出", Command.EXIT, 1);
                okCmd = new Command("确定", Command.OK, 1);
                backCmd = new Command("返回", Command.BACK, 1);
                setRepeat = new ChoiceGroup("模拟repeat事件?",Choice.EXCLUSIVE);
                setRepeat.append("否", null);
                setRepeat.append("是", null);
                timeInterval = new Gauge("时间间隔：200ms", true, 10, 0);
                myCanvas = new MyCanvas(this);
                repeatTimer = new Timer();
                task = new RepeatTask();
                form = new Form("Repeat事件选择");
                form.append(setRepeat);
                form.append(timeInterval);
                form.addCommand(exitCmd);
                form.addCommand(okCmd);
                form.setCommandListener(this);
                form.setItemStateListener(this);
        }

        public void startApp(){
                display.setCurrent(form);
        }

        public void pauseApp(){
        }

        public void destroyApp(boolean unconditional){
        }

        public void commandAction(Command c, Displayable d){

                if(c == exitCmd){
                        destroyApp(true);
                        notifyDestroyed();
                }
                else if(c == okCmd){
                        if(setRepeat.getSelectedIndex() == 0)
                                simRepeat = false;
                        else
                                simRepeat = true;
                        display.setCurrent(myCanvas);
                }
                else if(c == backCmd){
                        display.setCurrent(form);
                }
        }

        public void itemStateChanged(Item item){
                if(item == timeInterval){
                        int value = timeInterval.getValue();
                        timeInterval.setLabel("时间间隔："+(200+100*value)+"ms");
                }
        }

        class MyCanvas extends Canvas{

                int gameAction;
                int x, y;

                public MyCanvas(RepeatEventTest parent){
                        x = getWidth()/2;
                        y = getHeight()/2;
                        addCommand(backCmd);
                        setCommandListener(parent);
                }

                public void paint(Graphics g){
                        g.setColor(0xFFFFFF);
                        g.fillRect(0, 0, getWidth(), getHeight());
                        g.setColor(0);
                        g.fillRect(x, y, 20, 20);
                }

                public void showNotify(){
                        repeatTimer.schedule(task, 0);
                }

                public void hideNotify(){
                        repeatTimer.cancel();
                }

                public void keyPressed(int keyCode){
                        if(simRepeat){
                                gameAction = getGameAction(keyCode);
                                hasRepeat = true;
                        }
                        else{
                                gameAction = getGameAction(keyCode);
                                performGameAction();
                        }
                }

                public void keyReleased(int keyCode){
                        if(simRepeat){
                                hasRepeat = false;
                        }
                }

                public void keyRepeated(int keyCode){
                        if(hasRepeatEvents()){
                                keyPressed(keyCode);
                        }
                }

                void performGameAction(){
                        switch(gameAction){
                        case Canvas.UP:
                                if(y < getHeight()) y-=2;
                        break;
                        case Canvas.DOWN:
                                if(y > 0) y+=2;
                        break;
                        case Canvas.LEFT:
                                if(x > 0) x-=2;
                        break;
                        case Canvas.RIGHT:
                                if(y < getWidth()) x+=2;
                        break;
                        case Canvas.FIRE:
                                if(y < getWidth()) x+=2;
                        break;
                        }
                        repaint();
                }
        }

        class RepeatTask extends TimerTask{

                public void run(){
                        while(true){
                                while(hasRepeat){
                                        int interval = 200+100*timeInterval.getValue();
                                        try{
                                                myCanvas.performGameAction();
                                                Thread.sleep(interval);
                                        }
                                        catch(Exception ex){}
                                }
                        }
                }
        }
}