cannon.java

一些JAVA的小程序

import java.awt.*;

public class Cannon {
  public Cannon(Point location) {
    loc = location;
    setAngle(45);
  }

  private final Point loc;
  private int angle;
  private double radianAngle;

  public void setAngle(int a){
    angle = a;
    radianAngle = angle * Math.PI / 180.0;
  }

  public Ball fire(){
    Ball cannonBall = new CannonBall(new Point(loc),10,
      15 * Math.cos(radianAngle),
      -12 * Math.sin(radianAngle));
    return cannonBall;
  }

  public void paint(Graphics g){
    int barrelLength = 40;
    int barrelWidth = 8;
    int wheelRadius = 12;
      //draw wheel
    g.drawOval(loc.x - wheelRadius, loc.y - wheelRadius, 2 * wheelRadius, 2 * wheelRadius);

    int lv = (int) (barrelLength * Math.sin(radianAngle));
    int lh = (int) (barrelLength * Math.cos(radianAngle));
    int sh = (int) (barrelWidth * Math.sin(radianAngle));
    int sv = (int) (barrelWidth * Math.cos(radianAngle));
      //draw barrel
    g.drawLine(loc.x-sh, loc.y-sv, loc.x+sh, loc.y+sv);
    g.drawLine(loc.x-sh, loc.y-sv, loc.x+lh-sh, loc.y-lv-sv);
    g.drawLine(loc.x+sh, loc.y+sv, loc.x+lh+sh, loc.y-lv+sv);
    g.drawLine(loc.x+lh-sh, loc.y-lv-sv, loc.x+lh+sh, loc.y-lv+sv);
  }
}