按照书上写的武装飞船，写到能够左右移动了，但到了射击（装子弹）时候，按照书上的代码照搬了，运行时没显示代码有问题，但就是按了空格键，不见有子弹，其他都正常。

代码：

alien_invasion.py

import sys
import pygame
from pygame.sprite import Group

from settings import Settings
from ship import Ship
import game_functions as gf

def run_game():
    #初始化pygame、设置和屏幕对象
    pygame.init()
    ai_settings = Settings()
    screen = pygame.display.set_mode(
        (ai_settings.screen_width,ai_settings.screen_height))
    pygame.display.set_caption("Alien Invasion")

    #创建一艘飞船
    ship = Ship(ai_settings,screen)
    #创建一个用于存储子弹的编组
    bullets = Group()
            
    #开始游戏主循环
    while True:
        gf.check_events(ai_settings,screen,ship,bullets)
        ship.update()
        bullets.update()
        gf.update_screen(ai_settings,screen,ship,bullets)

run_game()


**game_functions.py**

import sys
import pygame

from bullet import Bullet

def check_keydown_events(event,ai_settings,screen,ship,bullets):
    """响应按键"""
    if event.key == pygame.K_RIGHT:
        ship.moving_right = True
    elif event.key == pygame.K_LEFT:
        ship.moving_left = True
    elif event.key == pygame.K_SPACE:
        #创建一颗子弹，并将其加入到编组bullets中
        new_bullet = Bullet(ai_settings,screen,ship)
        bullets.add(new_bullet)

def check_keyup_events(event,ship):
    """响应松开"""
    if event.key == pygame.K_RIGHT:
        ship.moving_right = False
    elif event.key == pygame.K_LEFT:
        ship.moving_left = False

def check_events(ai_settings,screen,ship,bullets):
    """响应按键和鼠标事件"""
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()

        elif event.type == pygame.KEYDOWN:
            check_keydown_events(event,ai_settings,screen,ship,bullets)

        elif event.type == pygame.KEYUP:
            check_keyup_events(event,ship)

def update_screen(ai_settings,screen,ship,bullets):
    """更新屏幕上的图像，并切换到新屏幕"""
    #每次循环时都重绘屏幕
    screen.fill(ai_settings.bg_color)
    ship.blitme()
    
    #让最近绘制的屏幕可见
    pygame.display.flip()

    #在飞船和外星人后面重绘所有子弹
    for bullet in bullets.sprites():
        bullet.draw_bullet()


**bullet.py**

import pygame
from pygame.sprite import Sprite

class Bullet(Sprite):
    """一个对飞船发射的子弹进行管理的类"""

    def __init__(self,ai_settings,screen,ship):
        """在飞船所处的位置创建一个子弹对象"""
        super(Bullet,self). __init__()
        self.screen = screen

        #在(0,0)处创建一个表示子弹的举行，再设置正确的位置
        self.rect = pygame.Rect(0,0,ai_settings.bullet_width,
            ai_settings.bullet_height)
        self.rect.centerx = ship.rect.centerx
        self.rect.top = ship.rect.top

        #存储用小数表示的子弹位置
        self.y = float(self.rect.y)

        self.color = ai_settings.bullet_color
        self.speed_factor = ai_settings.bullet_speed_factor


    def update(self):
        """向上移动子弹"""
        #更新表示子弹位置的小数值
        self.y -= self.speed_factor
        #更新表示子弹的rect的位置
        self.rect.y = self.y

    def draw_bullet(self):
        """在屏幕上绘制子弹"""
        pygame.draw.rect(self.screen,self.color,self.rect)

settings.py

class Settings():
    """存储《外星人入侵》的所有设置的类"""

    def __init__(self):
        """初始化游戏的设置"""
        #屏幕设置
        self.screen_width = 1200
        self.screen_height = 800
        self.bg_color = (230,230,230)

        #飞船的设置
        self.ship_speed_factor = 1.5

        #子弹设置
        self.bullet_speed_factor = 1
        self.bullet_width = 3
        self.bullet_height = 15
        self.bullet_color = 60,60,60
        

ship.py

import pygame

class Ship():

    def __init__(self,ai_settings,screen):
        """初始化飞船并设置其初始位置"""
        self.screen = screen
        self.ai_settings = ai_settings

        #加载飞船图像并获取其外接矩形
        self.image = pygame.image.load('images/ship.bmp')
        self.rect = self.image.get_rect()
        self.screen_rect = screen.get_rect()

        #将每艘新飞船放在屏幕底部中央
        self.rect.centerx = self.screen_rect.centerx
        self.rect.bottom = self.screen_rect.bottom

        #在飞船的属性center中存储小数值
        self.center = float(self.rect.centerx)

        #移动标志
        self.moving_right = False
        self.moving_left = False

    def update(self):
        """根据移动标志调整飞船的位置"""
        #更新飞船的center值，而不是rect
        if self.moving_right and self.rect.right < self.screen_rect.right:
            self.center += self.ai_settings.ship_speed_factor
        if self.moving_left and self.rect.left > 0:
            self.center -= self.ai_settings.ship_speed_factor

        #根据self.center更新rect对象
        self.rect.centerx = self.center

    def blitme(self):
        """在指定位置绘制飞船"""
        self.screen.blit(self.image,self.rect)