import java.awt.*;
import java.applet.*;
import java.awt.event.*;
import java.awt.image.*;
import java.awt.geom.*;
import java.util.*;
class Car{
Image img;
int x, y;
Dimension dim;
Car(Image img){
this.img=img;
}
Car(Image img, int x, int y){
this.img=img; this.x=x; this.y=y;
}
Car(Image img, int x, int y, Dimension dim){
this(img, x, y);
this.dim=dim;
}
void draw(Graphics g, ImageObserver observer){
g.drawImage(img, x, y, observer);
}
int getX(){ return x;}
int getY(){ return y;}
void setX(int x){this.x=x;}
void setY(int y){this.y=y;}
void setLocation(int x, int y){
this.x=x; this.y=y;
}
int getWidth(){ return img.getWidth(null);}
int getHeight(){ return img.getHeight(null);}
Rectangle2D getRectangle(){
return new Rectangle2D.Float(x, y, getWidth(), getHeight());
}
void move(int dx, int dy){
x+=dx;
y+=dy;
if(dim!=null){
if(x<0)x=0;
if(x+getWidth()>dim.getWidth())
x=(int)dim.getWidth()-getWidth();
}
}
boolean intersects(Car car){
return getRectangle().intersects(car.getRectangle());
}
boolean intersects(int x, int y){
return getRectangle().intersects(x, y, getWidth(), getHeight());
}
}
public class CarRace extends Applet implements KeyListener, Runnable{
Image buff;
Canvas screen;
Graphics2D gs, gb;
Car redCar;
Car[] enemy=new Car[20];
Button bStart;
Thread game;
boolean loop=true;
Dimension dim=new Dimension(200, 300);
int road;
Random rnd=new Random();
public void init(){
prepareResource();
setBackground(Color.blue);
initScreen();
add(screen);
bStart=new Button("game start");
add(bStart);
bStart.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent ae){
screen.requestFocus();
if(!game.isAlive())
game.start();
}
});
}
void prepareResource(){
Image imgRed=getImage(getCodeBase(),"images/red_car.gif");
Image imgBlue=getImage(getCodeBase(),"images/blue_car.gif");
Image imgGreen=getImage(getCodeBase(),"images/green_car.gif");
MediaTracker mt=new MediaTracker(this);
try{
mt.addImage(imgRed, 0);
mt.addImage(imgBlue, 1);
mt.addImage(imgGreen, 2);
mt.waitForAll();
}catch(Exception e){}
buff=createImage((int)dim.getWidth(), (int)dim.getHeight());
gb=(Graphics2D)buff.getGraphics();
redCar=new Car(imgRed, 80,250, dim);
for(int i=0;i<10;i++){
enemy[i]=new Car(imgBlue, 0, 0);
}
for(int i=10;i<enemy.length;i++){
enemy[i]=new Car(imgGreen, 0, 0);
}
for(int i=0;i<enemy.length;i++){
setEnemy(i);
}
game=new Thread(this);
}
public void stop(){
loop=false;
}
public void run(){
while(loop){
drawScreen();
try{ Thread.sleep(50);}catch(Exception e){}
}
}
void initScreen(){
screen=new Canvas(){
public void paint(Graphics g){
if(gs==null){
gs=(Graphics2D)screen.getGraphics();
}
drawScreen();
}
};
screen.setSize(dim);
screen.addKeyListener(this);
}
void setEnemy(int en){
int x, y;
next:while(true){
x=rnd.nextInt((int)dim.getWidth()-enemy[en].getWidth());
y=-rnd.nextInt(5000)-200;
for(int j=0;j<enemy.length;j++){
if(j!=en && enemy[j].intersects(x, y))continue next;
}
enemy[en].setLocation(x, y);
break;
}
}
void check(Car en){
if(redCar.intersects(en)){
if(redCar.getX()>en.getX()){
en.move(-20, 0);
redCar.move(20, 0);
}
else{
en.move(20,0);
redCar.move(-20, 0);
}
}
}
synchronized void drawScreen(){
gb.clearRect(0, 0, (int)dim.getWidth(), (int)dim.getHeight());
gb.setPaint(new Color(100, 100, 100));
gb.fillRect(0, 0, (int)dim.getWidth(), (int)dim.getHeight());
drawRoad();
for(int i=0;i<enemy.length;i++){
enemy[i].move(0, 15);
enemy[i].draw(gb, screen);
if(enemy[i].getY()>dim.getHeight())
setEnemy(i);
check(enemy[i]);
}
redCar.draw(gb, screen);
gs.drawImage(buff, 0,0, screen);
}
void drawRoad(){
road+=80;
gb.setPaint(Color.yellow);
gb.fillRect((int)dim.getWidth()/2, road,10,150);
if(road>=dim.getHeight())road=-150;
}
public void keyPressed(KeyEvent ke){
if(ke.getKeyCode()==KeyEvent.VK_LEFT){
redCar.move(-10,0);
}
else if(ke.getKeyCode()==KeyEvent.VK_RIGHT){
redCar.move(10,0);
}
}
public void keyReleased(KeyEvent ke){}
public void keyTyped(KeyEvent ke){}
}
嵌入到html：
<Applet code="CarRace.class" width=250 height=350 >
</Applet>