北教學習執行個體一 自由滾動的小球

      今天無意看到以前在“北教”學習J2ME遊戲時做的作品，都是些很基礎的入門的東西，而且當初全是在模擬器上跑，都沒拿真機測過，想想也蠻汗的。看了下代碼，覺得其中好些當初在實現時的想法卻也有些巧妙的，於是打算花點時間，把以前的這些作品一一整理出來。

      由於當初學習時間只有半年，而且大多都只是課後老師布置的練習，故所寫的這些比較簡單且粗糙，所以大夥別抱太大期望。當然，我會儘可能重新最佳化完善，並給出詳細注釋。希望對J2ME有興趣，卻還未入門的朋友看了後能有收穫。

      這個是當初剛學Canvas介面時寫的，主要是圓的繪製、設定顏色、控制物體座標的改變。

 

      最終：

     

      

 

 

 

      下邊貼出代碼

 

GameMIDlet類：

package rollBall;</p><p>import javax.microedition.midlet.MIDlet;<br />import javax.microedition.lcdui.*;<br />/**<br /> *<br /> * @author kf156(亞日)<br /> *<br /> */<br />public class GameMIDlet extends MIDlet {<br />private static GameMIDlet instance;</p><p>private GameCanvas game;</p><p>public GameMIDlet() {<br />instance = this;<br />}</p><p>protected void destroyApp(boolean arg0) {<br />}</p><p>protected void pauseApp() {<br />}</p><p>protected void startApp() {<br />if (game == null) {<br />game = new GameCanvas();<br />}<br />Display.getDisplay(this).setCurrent(game);<br />}</p><p>public static void quitApp() {<br />instance.destroyApp(true);<br />instance.notifyDestroyed();<br />instance = null;<br />}<br />}<br />

 

GameCanvas類

 package rollBall;</p><p>import javax.microedition.lcdui.Canvas;<br />import javax.microedition.lcdui.Graphics;</p><p>/**<br /> * 自由滾動的小球<br /> *<br /> * @author kf156(亞日)<br /> *<br /> */<br />public class GameCanvas extends Canvas implements Runnable {<br />public Thread thread;</p><p>public boolean running = true;</p><p>public int width, height, ballX = 0, ballY = 0, ballAngle = 0;</p><p>private final int DIAMETER = 40;// 小球直徑</p><p>public int[] key = new int[4];</p><p>private final int DISTANCE = 5;// 每次移動的距離</p><p>private final int ANGLE = 12;// 每次轉動的角度</p><p>public final static int KEY_UP = -1;// 上</p><p>public final static int KEY_DOWN = -2;// 下</p><p>public final static int KEY_LEFT = -3;// 左</p><p>public final static int KEY_RIGHT = -4;// 右</p><p>public GameCanvas() {<br />setFullScreenMode(true);<br />startThread();<br />init();<br />}</p><p>public void free() {<br />}</p><p>public void init() {<br />width = getWidth();<br />height = getHeight();<br />}</p><p>public void input() { // 判斷<br />key[0] = key[2];<br />key[1] = key[3];<br />key[2] = 0;<br />}</p><p>public void update() {</p><p>switch (key[1]) {</p><p>case KEY_UP:<br />ballY -= DISTANCE;<br />ballAngle += ANGLE;<br />if (ballY < -DIAMETER)<br />ballY = height;<br />break;<br />case KEY_DOWN:<br />ballY += DISTANCE;<br />ballAngle -= ANGLE;<br />if (ballY > height)<br />ballY = -DIAMETER;<br />break;<br />case KEY_LEFT:<br />ballX -= DISTANCE;<br />ballAngle += ANGLE;<br />if (ballX < -DIAMETER)<br />ballX = width;<br />break;<br />case KEY_RIGHT:<br />ballX += DISTANCE;<br />ballAngle -= ANGLE;<br />if (ballX > width)<br />ballX = -DIAMETER;<br />break;</p><p>}</p><p>}</p><p>protected void paint(Graphics g) {</p><p>g.setColor(0x000000);<br />g.fillRect(0, 0, width, height);</p><p>// 正轉的小球<br />g.setColor(0x00ff00);<br />g.fillArc(ballX, ballY, DIAMETER, DIAMETER, 0, 360);</p><p>g.setColor(0x0000ff);<br />g.fillArc(ballX, ballY, DIAMETER, DIAMETER, ballAngle + 60, 60);<br />g.fillArc(ballX, ballY, DIAMETER, DIAMETER, ballAngle + 180, 60);<br />g.fillArc(ballX, ballY, DIAMETER, DIAMETER, ballAngle + 300, 60);</p><p>}</p><p>public void startThread() {<br />if (thread == null) {<br />thread = new Thread(this);<br />thread.start();<br />}<br />}</p><p>public void run() {<br />int debug = 0;<br />try {<br />while (running) {<br />long start = System.currentTimeMillis();<br />input();<br />debug = 1;<br />update();<br />debug = 2;<br />repaint();<br />serviceRepaints();<br />Thread.yield();<br />long end = System.currentTimeMillis() - start;<br />if (end < 50)<br />Thread.sleep(50 - end);<br />}<br />GameMIDlet.quitApp();<br />} catch (Exception e) {<br />System.err.println("run error:" + e + "debug:" + debug);<br />}<br />}</p><p>// 當按鍵按下時<br />protected void keyPressed(int keyCode) {<br />key[2] = key[3] = keyCode;<br />}</p><p>// 當按鍵釋放時<br />public void keyReleased(int keyCode) {<br />key[3] = 0;<br />}<br />}<br />

 

 

  

 工程已經上傳，覺得網頁上看不方便的朋友也可直接下載：http://download.csdn.net/source/1569954