J2ME自由滚动的小球

package rollBall; import javax.microedition.lcdui.Canvas; import javax.microedition.lcdui.Graphics; /** * 自由滚动的小球 * * @author kf156(亚日) * */ public class GameCanvas extends Canvas implements Runnable { public Thread thread; public boolean running = true; public int width, height, ballX = 0, ballY = 0, ballAngle = 0; private final int DIAMETER = 40;// 小球直径 public int[] key = new int[4]; private final int DISTANCE = 5;// 每次移动的距离 private final int ANGLE = 12;// 每次转动的角度 public final static int KEY_UP = -1;// 上 public final static int KEY_DOWN = -2;// 下 public final static int KEY_LEFT = -3;// 左 public final static int KEY_RIGHT = -4;// 右 public GameCanvas() { setFullScreenMode(true); startThread(); init(); } public void free() { } public void init() { width = getWidth(); height = getHeight(); } public void input() { // 判断 key[0] = key[2]; key[1] = key[3]; key[2] = 0; } public void update() { switch (key[1]) { case KEY_UP: ballY -= DISTANCE; ballAngle += ANGLE; if (ballY < -DIAMETER) ballY = height; break; case KEY_DOWN: ballY += DISTANCE; ballAngle -= ANGLE; if (ballY > height) ballY = -DIAMETER; break; case KEY_LEFT: ballX -= DISTANCE; ballAngle += ANGLE; if (ballX < -DIAMETER) ballX = width; break; case KEY_RIGHT: ballX += DISTANCE; ballAngle -= ANGLE; if (ballX > width) ballX = -DIAMETER; break; } } protected void paint(Graphics g) { g.setColor(0x000000); g.fillRect(0, 0, width, height); // 正转的小球 g.setColor(0x00ff00); g.fillArc(ballX, ballY, DIAMETER, DIAMETER, 0, 360); g.setColor(0x0000ff); g.fillArc(ballX, ballY, DIAMETER, DIAMETER, ballAngle + 60, 60); g.fillArc(ballX, ballY, DIAMETER, DIAMETER, ballAngle + 180, 60); g.fillArc(ballX, ballY, DIAMETER, DIAMETER, ballAngle + 300, 60); } public void startThread() { if (thread == null) { thread = new Thread(this); thread.start(); } } public void run() { int debug = 0; try { while (running) { long start = System.currentTimeMillis(); input(); debug = 1; update(); debug = 2; repaint(); serviceRepaints(); Thread.yield(); long end = System.currentTimeMillis() - start; if (end < 50) Thread.sleep(50 - end); } GameMIDlet.quitApp(); } catch (Exception e) { System.err.println("run error:" + e + "debug:" + debug); } } // 当按键按下时 protected void keyPressed(int keyCode) { key[2] = key[3] = keyCode; } // 当按键释放时 public void keyReleased(int keyCode) { key[3] = 0; } }