cannonworld.java

一些JAVA的小程序

//
//	CannonWorld application, second version of Cannon Game
//	Described in Chapter 6 of
//	Understanding Object-Oriented Programming with Java
//	by Timothy A Budd
//	Published by Addison-Wesley
//
//	see ftp://ftp.cs.orst.edu/pub/budd/java/ReadMe.html
//	for further information
//
//

import java.awt.*;
import java.awt.event.*;

class CannonWorld extends Frame {

	public static void main (String [ ] args)
	{
		CannonWorld world = new CannonWorld ();
		world.show ();
	}

	public static final int FrameWidth = 600;
	public static final int FrameHeight = 400;

	private int angle = 45;
	private String message = "Angle: " + angle;
	private CannonBall cannonBall = null;
	private Scrollbar slider;

	private class FireButtonListener implements ActionListener {
		public void actionPerformed (ActionEvent e) {
			double radianAngle = angle * Math.PI / 180.0;
			double sinAngle = Math.sin(radianAngle);
			double cosAngle = Math.cos(radianAngle);
			// create the cannon ball
			cannonBall = new CannonBall (
				20 + (int) (30 * cosAngle), dy(5+(int) (30 * sinAngle)),
				5, 12 * cosAngle, -12 * sinAngle);
			repaint();
			}
	}

	private class ScrollBarListener implements AdjustmentListener {
		public void adjustmentValueChanged (AdjustmentEvent e) {
			angle = slider.getValue();
			message = "Angle: " + angle;
			repaint();
			}
	}

	public CannonWorld () {
		setSize (FrameWidth, FrameHeight);
		setTitle ("Cannon Game");

			// add the scroll bar
		Button fire = new Button("fire");
		fire.addActionListener(new FireButtonListener());
		add ("North", fire);
		slider = new Scrollbar(Scrollbar.VERTICAL, angle, 5, 0, 90);
		slider.addAdjustmentListener(new ScrollBarListener());
		add ("East", slider);
	}

	public static int dy (int y) {	return FrameHeight - y; }

	public void paint (Graphics g)
	{
		int x = 20;	// location of cannon
		int y = 15;
		double radianAngle = angle * Math.PI / 180.0;
		int lv = (int) (30 * Math.sin(radianAngle));
		int lh = (int) (30 * Math.cos(radianAngle));
		int sv = (int) (10 * Math.sin(radianAngle + Math.PI/2));
		int sh = (int) (10 * Math.cos(radianAngle + Math.PI/2));
			// draw cannon
		g.setColor(Color.green);
		g.drawLine(x, dy(y), x+lh, dy(y+lv));
		g.drawLine(x+lh, dy(y+lv), x+lh+sh, dy(y+lv+sv));
		g.drawLine(x+lh+sh, dy(y+lv+sv), x+sh, dy(y+sv));
		g.drawLine(x+sh, dy(y+sv), x, dy(y));
		g.drawOval(x-8, dy(y+10), 12, 12);
			// draw target
		g.setColor(Color.red);
		g.fillRoundRect(FrameWidth-100, dy(12), 50, 10, 6, 6);
			// draw cannonball
		if (cannonBall != null) { 
			cannonBall.move();
			cannonBall.paint(g);
			//try {
				//Thread.sleep(20);
				//} catch(InterruptedException e) { }
			if (dy(cannonBall.y()) > 0) 
				repaint();
			else {
				int targetX = FrameWidth - 100;
				if ((cannonBall.x() > targetX) && (cannonBall.x() < (targetX + 50)))
					message = "You Hit It!";
				else
					message = "Missed!";
				cannonBall = null;
				}
			}
		g.drawString(message, FrameWidth/2, FrameHeight/2);
	}
}