ch24 实验十二 Canvas(三)随机数字

实验 Canvas(三)
一．实验目的：
1．掌握JDK的安装和环境变量的配置
2．掌握WTK的安装
3．能够使用JDK和WTK完成基本的实验内容
二．实验内容
编写下列程序
【案例1】点OK键，图像会旋转
public class MIDletRot extends MIDlet {
private MyCanvas mc = new MyCanvas();
private Display dis;
protected void startApp() throws MIDletStateChangeException {
dis = Display.getDisplay(this);
mc.setTitle("按键画布");
dis.setCurrent(mc);
}
class MyCanvas extends Canvas{
private Image img;
private int x;
private int y;
private int TRANS = Sprite.TRANS_NONE;
public MyCanvas(){
try{
img = Image.createImage("/img.png");
x = 0;
y = 0;
}catch(Exception ex){}
}
public void paint(Graphics g){
//画布清空
g.setColor(0,0,255);
g.fillRect(0,0,this.getWidth(),this.getHeight());
g.drawRegion(img,0,0,img.getWidth(),img.getHeight(),TRANS,x,y,Graphics.LE FT|Graphics.TOP);
}
protected void keyRepeated(int keyCode) {
int action = this.getGameAction(keyCode);
switch(action){
case Canvas.UP: y -= 5; break;
case Canvas.DOWN: y += 5; b reak;
case Canvas.LEFT: x -= 5; break;
case Canvas.RIGHT: x += 5; b reak;
}
repaint();//调用paint函数重画
}
protected void keyPressed(int keyCode) {
int action = this.getGameAction(keyCode);
if (action==Canvas.FIRE){
switch(TRANS){
case Sprite.TRANS_NONE: TRANS = Sprite.TRANS_ROT90;
break;
case Sprite.TRANS_ROT90: TRANS = Sprite.TRANS_ROT180;
break;
case Sprite.TRANS_ROT180: T RANS = Sprite.TRANS_ROT270;
break;
case Sprite.TRANS_ROT270: T RANS = Sprite.TRANS_NONE;
break;
}
}
repaint();//调用paint函数重画
}
}
}
【案例2】界面上每秒钟在随机位置出现随机颜色的数字0-9
public class MIDletNum extends MIDlet {
private NumberCanvas nc = new NumberCanvas();
private Display dis;
protected void startApp() throws MIDletStateChangeException {
dis = Display.getDisplay(this);
dis.setCurrent(nc);
}
class NumberCanvas extends Canvas implements Runnable{
private char rndChar;
private Random rnd = new Random();
public NumberCanvas(){
new Thread(this).start();
}
public void paint(Graphics g){
Font font =
Font.getFont(Font.FACE_SYSTEM,Font.STYLE_BOLD,Font.SIZE_LARGE);
g.setFont(font);
g.setColor(rnd.nextInt(256),rnd.nextInt(256),rnd.nextInt(256));
int x = rnd.nextInt(this.getWidth());
int y = rnd.nextInt(this.getHeight());
g.drawChar(rndChar, x, y, Graphics.TOP|Graphics.LEFT);
System.out.println(rndChar);
}
public void run(){
while(true){
int number = '0' + rnd.nextInt(10);
//0-9之间的数字，转成字符不是0-9
rndChar = (char)number;
repaint();
try{
Thread.sleep(1000);
}catch(Exception ex){}
}
}
public void keyPressed(int keyCode){
//将keyCode和rndChar表示的数字比较，评分}
}
}
三、试验体会。