fallingcow.java

书籍"Java_面向事件编程"的附带光盘代码

import objectdraw.*;
import java.applet.*;
import java.awt.*;

// creates a falling cow image

public class FallingCow extends FallingObject {
    
    private static final int COW_HEIGHT = 70;
    private static final int COW_WIDTH = 100;
    private static final int COW_PAUSE = 30;
    private static final int COW_WALK_SPEED = -3;
    private static final int COW_FALL_SPEED = 4;
    
    
    private DrawingCanvas canvas;
    
    // image for walking cow
    private Image cow;
    
    // be sure to import java.applet.awt
    private AudioClip moo;
    
    // Creates a falling purple cow
    public FallingCow(DrawingCanvas aCanvas,
                      Image upsideDownCow,
                      Image aCow,
                      AudioClip aMoo,
                      double x, int groundHeight) {
        // Create a generic falling object
        super (groundHeight - COW_HEIGHT, COW_FALL_SPEED);
        
        canvas = aCanvas;
        cow = aCow;
        moo = aMoo;
        
        // Specialize it to be an upside down cow.
        object = new VisibleImage(upsideDownCow, x,
                                  -COW_HEIGHT, canvas);
        
        // Start it falling
        start();
    }
    
    protected void hitBottom() {
        // play moooing noise
        moo.play();
        
        // let superclass do what it wants to
        super.hitBottom();
        
        // make cow walk back to the left
        VisibleImage walkingCow =
            new VisibleImage(cow, object.getLocation(), canvas);
        
        while (walkingCow.getX() + COW_WIDTH > 0) {
            pause(COW_PAUSE);
            walkingCow.move(COW_WALK_SPEED, 0);
        }
        
        walkingCow.removeFromCanvas();
    }
}