gamescreeninputenable.java

《j2me开发精解〉（詹健飞）CD-rom附带源码。用netbeans

package com.j2medev.chapter5.example;

import javax.microedition.lcdui.Font;
import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.game.*;

import java.util.Random;

final class GameScreenInputEnable extends GameCanvas implements Runnable {
    
    private Graphics graphics; //保存图形环境实例
    
    private boolean runningFlag = false; //线程运行标志
    
    private static final long TIME_PER_FRAME = 100;// 每一帧的周期
    
    private int width;//屏幕宽度
    
    private int height;//屏幕高度
    
    InputManager inputManager = new InputManager();
    
    ///////////////////////自定义部分开始/////////////////////////////////
    InputAction upAction = new InputAction(InputAction.MODE_INITAL_ONLY);
    
    InputAction downAction = new InputAction();
    
    private Random random = new Random(); //设置一个随机数;
    
    public static final int BLUE = 0x000000ff;
    
    private int x, y, vx, vy;
    
    String str = "J2ME Game World!";
    
    ///////////////////////自定义部分结束/////////////////////////////////
    
    GameScreenInputEnable(boolean flag) { //构造方法;
        super(flag);
        graphics = getGraphics();//取得图形环境实例
        width = getWidth();
        height = getHeight();
        init();
    }
    
    void init() { //初始化游戏数据；
        ///////////////////////自定义部分开始/////////////////////////////////
        x = width / 2;
        y = height / 2;
        vx = random.nextInt(2) + 1;
        vy = random.nextInt(2) + 1;
        inputManager.mapkeyCodeToInputAction(KEY_NUM2, upAction);
        inputManager.mapkeyCodeToInputAction(KEY_NUM8, downAction);
        inputManager.mapkeyCodeToInputAction(-1,upAction);
        inputManager.mapkeyCodeToInputAction(-2,downAction);
        
        ///////////////////////自定义部分结束/////////////////////////////////
    }
    
    //	private long leftLastPressdTime = 0;
    //	private long limit = 100;//定100ms的阈值
    //
    //	private boolean leftFlag=false;//标记
    private void input() { //处理输入
        ///////////////////////自定义部分开始/////////////////////////////////
        if(upAction.isPressed()){
            y-=5;
        }
        if(downAction.isPressed()){
            y+=3;
        }
        ///////////////////////自定义部分结束/////////////////////////////////
    }
    
    private void logic() { //更新逻辑
        ///////////////////////自定义部分开始/////////////////////////////////
        x += vx;
        y += vy;
        Font font = graphics.getFont();
        if (x <= 0 || x + font.stringWidth(str) >= width) {
            vx = -vx;
        }
        if (y <= 0 || y + 20 >= height) {
            vy = -vy;
        }
        ///////////////////////自定义部分结束/////////////////////////////////
    }
    
    private void render(Graphics g) { //渲染画面
        ///////////////////////自定义部分开始/////////////////////////////////
        g.setColor(BLUE);
        g.fillRect(0, 0, width, height);
        g.setColor(0x00ffffff);
        g.drawString(str, x, y, Graphics.LEFT | Graphics.TOP);
        //System.out.println(width+","+height);
        ///////////////////////自定义部分结束/////////////////////////////////
    }
    
    synchronized public void start() {
        if (!runningFlag) {
            runningFlag = true;
            Thread th = new Thread(this);//启动线程
            th.start();
        }
    }
    
    synchronized public void stop() {
        runningFlag = false;
    }
    
    public void run() {
        System.out.println("Game main loop start");
        while (runningFlag) {
            long startTime = System.currentTimeMillis();
            input();
            logic();
            render(graphics);
            flushGraphics();//更新显示屏幕
            long elapsedTime = System.currentTimeMillis() - startTime;
            if (elapsedTime < TIME_PER_FRAME) {
                try {
                    Thread.sleep(TIME_PER_FRAME - elapsedTime);
                } catch (InterruptedException ex) {
                }
            }
        }
        System.out.println("Game main loop stop");
    }
    
    protected void keyPressed(int keyCode) {
        inputManager.keyPressed(keyCode);
    }
    
    protected void keyReleased(int keyCode) {
        inputManager.keyReleased(keyCode);
    }
    
    protected void keyRepeated(int keyCode) {
        inputManager.keyRepeated(keyCode);
    }
}