Sprite的主要构造方法有：
Sprite(Image)：构造一个单幅图案的Sprite；
Sprite(Image, int width, int height)：构造一个动画Sprite，图片将按照指定大小被分为N个Frame，通过setFrame(int index)就可以让Sprite动起来。我们用了一个有透明背景的png图片创建坦克的Sprite：
（注重这个图是放大的JPG格式，你需要用Photoshop之类的软件处理成有透明背景的png格式，大小为64x16）
我们在Eclipse中建立如下工程和目录：
以下是画出Sprite的TankGameCanvas.java：
package tank.midp.core;import javax.microedition.lcdui.*;import javax.microedition.lcdui.game.*;public class TankGameCanvas extends GameCanvas implements Runnable { // 控制方向： private static int INDEX_OF_UP = 0; private static int INDEX_OF_DOWN = 1; private static int INDEX_OF_LEFT = 3; private static int INDEX_OF_RIGHT = 2; private boolean isPlay; // Game Loop runs when isPlay is true private long delay; // To give thread consistency private int currentX, currentY; // To hold current position of the 'X' private int width; // To hold screen width private int height; // To hold screen height private Sprite spriteTank; // our sprite! // Constructor and initialization public TankGameCanvas() { super(true); width = getWidth(); height = getHeight(); currentX = width / 2; currentY = height / 2; delay = 20; // init sprite: try { Image image = Image.createImage("/res/img/player1.png"); // 注重路径 spriteTank = new Sprite(image, 16, 16); // 大小是16x16 } catch(Exception e) { e.printStackTrace(); } } // Automatically start thread for game loop public void start() { isPlay = true; new Thread(this).start(); } public void stop() { isPlay = false; } // Main Game Loop public void run() { Graphics g = getGraphics(); while (isPlay) { input(); drawScreen(g); try { Thread.sleep(delay); } catch (InterruptedException ie) {} } } // Method to Handle User Inputs private void input() { int keyStates = getKeyStates(); // Left if ((keyStates & LEFT_PRESSED) != 0) { currentX = Math.max(0, currentX - 1); spriteTank.setFrame(INDEX_OF_LEFT); } // Right if ((keyStates & RIGHT_PRESSED) !=0 ) { if ( currentX + 5 width) currentX = Math.min(width, currentX + 1); spriteTank.setFrame(INDEX_OF_RIGHT); } // Up if ((keyStates & UP_PRESSED) != 0) { currentY = Math.max(0, currentY - 1); spriteTank.setFrame(INDEX_OF_UP); } // Down if ((keyStates & DOWN_PRESSED) !=0) { if ( currentY + 10 height) currentY = Math.min(height, currentY + 1); spriteTank.setFrame(INDEX_OF_DOWN); } } // Method to Display Graphics private void drawScreen(Graphics g) { g.setColor(0); // black g.fillRect(0, 0, getWidth(), getHeight()); // 画一个Sprite非常简单： spriteTank.setPosition(currentX, currentY); spriteTank.paint(g); flushGraphics(); }}
运行后的画面如下，可以用上下左右控制坦克：
