根据主战坦克的方向和位置，打出子弹

[java]代码库

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

public class TankClient extends Frame {
	public static final int GAME_WIDTH = 800;
	public static final int GAME_HEIGHT = 600;
	
	Tank myTank = new Tank(50, 50, this);
	Missile m = null;
	
	Image offScreenImage = null;
	
	public void paint(Graphics g) {
		if(m!=null) m.draw(g);
		myTank.draw(g);
	}
	
	public void update(Graphics g) {
		if(offScreenImage == null) {
			offScreenImage = this.createImage(GAME_WIDTH, GAME_HEIGHT);
		}
		Graphics gOffScreen = offScreenImage.getGraphics();
		Color c = gOffScreen.getColor();
		gOffScreen.setColor(Color.GREEN);
		gOffScreen.fillRect(0, 0, GAME_WIDTH, GAME_HEIGHT);
		gOffScreen.setColor(c);
		paint(gOffScreen);
		g.drawImage(offScreenImage, 0, 0, null);
	}

	public void lauchFrame() {
		this.setLocation(400, 300);
		this.setSize(GAME_WIDTH, GAME_HEIGHT);
		this.setTitle("TankWar");
		this.addWindowListener(new WindowAdapter() {
			public void windowClosing(WindowEvent e) {
				System.exit(0);
			}
		});
		this.setResizable(false);
		this.setBackground(Color.GREEN);
		
		this.addKeyListener(new KeyMonitor());
		
		setVisible(true);
		
		new Thread(new PaintThread()).start();
	}

	public static void main(String[] args) {
		TankClient tc = new TankClient();
		tc.lauchFrame();
	}
	
	private class PaintThread implements Runnable {

		public void run() {
			while(true) {
				repaint();
				try {
					Thread.sleep(50);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		}
	}
	
	private class KeyMonitor extends KeyAdapter {

		public void keyReleased(KeyEvent e) {
			myTank.keyReleased(e);
		}

		public void keyPressed(KeyEvent e) {
			myTank.keyPressed(e);
		}
		
	}
}




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

public class Tank {
	public static final int XSPEED = 5;
	public static final int YSPEED = 5;
	
	public static final int WIDTH = 30;
	public static final int HEIGHT = 30;
	
	TankClient tc;
	
	private int x, y;
	
	private boolean bL=false, bU=false, bR=false, bD = false;
	enum Direction {L, LU, U, RU, R, RD, D, LD, STOP};
	
	private Direction dir = Direction.STOP;

	public Tank(int x, int y) {
		this.x = x;
		this.y = y;
	}
	
	public Tank(int x, int y, TankClient tc) {
		this(x, y);
		this.tc = tc;
	}
	
	public void draw(Graphics g) {
		Color c = g.getColor();
		g.setColor(Color.RED);
		g.fillOval(x, y, WIDTH, HEIGHT);
		g.setColor(c);
		
		move();
	}
	
	void move() {
		switch(dir) {
		case L:
			x -= XSPEED;
			break;
		case LU:
			x -= XSPEED;
			y -= YSPEED;
			break;
		case U:
			y -= YSPEED;
			break;
		case RU:
			x += XSPEED;
			y -= YSPEED;
			break;
		case R:
			x += XSPEED;
			break;
		case RD:
			x += XSPEED;
			y += YSPEED;
			break;
		case D:
			y += YSPEED;
			break;
		case LD:
			x -= XSPEED;
			y += YSPEED;
			break;
		case STOP:
			break;
		}
	}
	
	public void keyPressed(KeyEvent e) {
		int key = e.getKeyCode();
		switch(key) {
		case KeyEvent.VK_CONTROL:
			tc.m = fire();
			break;
		case KeyEvent.VK_LEFT :
			bL = true;
			break;
		case KeyEvent.VK_UP :
			bU = true;
			break;
		case KeyEvent.VK_RIGHT :
			bR = true;
			break;
		case KeyEvent.VK_DOWN :
			bD = true;
			break;
		}
		locateDirection();
	}
	
	void locateDirection() {
		if(bL && !bU && !bR && !bD) dir = Direction.L;
		else if(bL && bU && !bR && !bD) dir = Direction.LU;
		else if(!bL && bU && !bR && !bD) dir = Direction.U;
		else if(!bL && bU && bR && !bD) dir = Direction.RU;
		else if(!bL && !bU && bR && !bD) dir = Direction.R;
		else if(!bL && !bU && bR && bD) dir = Direction.RD;
		else if(!bL && !bU && !bR && bD) dir = Direction.D;
		else if(bL && !bU && !bR && bD) dir = Direction.LD;
		else if(!bL && !bU && !bR && !bD) dir = Direction.STOP;
	}

	public void keyReleased(KeyEvent e) {
		int key = e.getKeyCode();
		switch(key) {
		case KeyEvent.VK_LEFT :
			bL = false;
			break;
		case KeyEvent.VK_UP :
			bU = false;
			break;
		case KeyEvent.VK_RIGHT :
			bR = false;
			break;
		case KeyEvent.VK_DOWN :
			bD = false;
			break;
		}
		locateDirection();		
	}
	
	public Missile fire() {
		int x = this.x + Tank.WIDTH/2 - Missile.WIDTH/2;
		int y = this.y + Tank.HEIGHT/2 - Missile.HEIGHT/2;
		Missile m = new Missile(x, y, dir);
		return m;
	}
}


import java.awt.*;

public class Missile {
	public static final int XSPEED = 10;
	public static final int YSPEED = 10;
	
	public static final int WIDTH = 10;
	public static final int HEIGHT = 10;
	
	
	int x, y;
	Tank.Direction dir;
	
	public Missile(int x, int y, Tank.Direction dir) {
		this.x = x;
		this.y = y;
		this.dir = dir;
	}
	
	public void draw(Graphics g) {
		Color c = g.getColor();
		g.setColor(Color.BLACK);
		g.fillOval(x, y, WIDTH, HEIGHT);
		g.setColor(c);
		
		move();
	}

	private void move() {
		switch(dir) {
		case L:
			x -= XSPEED;
			break;
		case LU:
			x -= XSPEED;
			y -= YSPEED;
			break;
		case U:
			y -= YSPEED;
			break;
		case RU:
			x += XSPEED;
			y -= YSPEED;
			break;
		case R:
			x += XSPEED;
			break;
		case RD:
			x += XSPEED;
			y += YSPEED;
			break;
		case D:
			y += YSPEED;
			break;
		case LD:
			x -= XSPEED;
			y += YSPEED;
			break;
		}
		
	}
	
}