浅谈 Web框架

一、Web框架本质

• 所有的Web应用本质上就是一个socket服务端，而用户的浏览器就是一个socket客户端

二、Web框架功能

• socket收发消息 —— wsgiref（测试）、uwsgi（线上）

• 根据不同的路径返回不同的字符串

• 返回动态页面（字符串的替换）—— jinja2

三、Web框架种类

• django

  • 根据不同的路径返回不同的字符串

  • 返回动态页面（字符串的替换）

• flask

  • 根据不同的路径返回不同的字符串

• tornado

  • socket收发消息

  • 根据不同的路径返回不同的字符串

  • 返回动态页面（字符串的替换）

四、自定义web框架

• 简单示例：socket服务端

  import socket
  # 创建一个socket对象
  sk = socket.socket()
  # 绑定IP和端口
  sk.bind(('127.0.0.1', 8000))
  # 监听
  sk.listen(5)
  # 等待连接
  while True:
      conn, addr = sk.accept()
      # 接收数据
      data= conn.recv(1024)
      print(data)
      # 返回数据
      conn.send(b'HTTP/1.1 200 OK
  
  <h1>ok!</h1>')
      # 断开连接
      conn.close()

• 根据不同路径返回不同的内容（普通版）

  import socket
  # 创建一个socket对象
  sk = socket.socket()
  # 绑定IP和端口
  sk.bind(('127.0.0.1', 8000))
  # 监听
  sk.listen(5)
  # 等待连接
  while True:
      conn, addr = sk.accept()
      # 接收数据
      data = conn.recv(1024)
      data = data.decode('utf-8')
      url = data.split()[1]
      conn.send(b'HTTP/1.1 200 OK
  
  ')
      if url == '/index/':
          # 返回数据
          conn.send(b'<h1>index!</h1>')
      elif url == '/home/':
          conn.send(b'<h1>home!</h1>')
      else:
          conn.send(b'<h1>404 not found!</h1>')
      # 断开连接
      conn.close()

  import socket
  # 创建一个socket对象
  sk = socket.socket()
  # 绑定IP和端口
  sk.bind(('127.0.0.1', 8000))
  # 监听
  sk.listen(5)
  # 函数
  def index(url):
      ret = '<h1>index!</h1>({})'.format(url)
      return ret.encode('utf-8')
  def home(url):
      ret = '<h1>home!</h1>({})'.format(url)
      return ret.encode('utf-8')
  # 等待连接
  while True:
      conn, addr = sk.accept()
      # 接收数据
      data = conn.recv(1024)
      data = data.decode('utf-8')
      url = data.split()[1]
      conn.send(b'HTTP/1.1 200 OK
  
  ')
      if url == '/index/':
          # 返回数据
          ret = index(url)
      elif url == '/home/':
          ret = home(url)
      else:
          ret = b'<h1>404 not found!</h1>'
      conn.send(ret)
      # 断开连接
      conn.close()

  import socket
  # 创建一个socket对象
  sk = socket.socket()
  # 绑定IP和端口
  sk.bind(('127.0.0.1', 8000))
  # 监听
  sk.listen(5)
  # 函数
  def index(url):
      ret = '<h1>index!</h1>({})'.format(url)
      return ret.encode('utf-8')
  def home(url):
      ret = '<h1>home!</h1>({})'.format(url)
      return ret.encode('utf-8')
  # 定义一个list1和实际要执行的函数的对应关系 
  list1 = [
      ('/index/', index),
      ('/home/', home),
  ]
  # 等待连接
  while True:
      conn, addr = sk.accept()
      # 接收数据
      data = conn.recv(1024)
      data = data.decode('utf-8')
      url = data.split()[1]
      conn.send(b'HTTP/1.1 200 OK
  
  ')
      func = None
      for i in list1:
          if url == i[0]:
              func = i[1]
              break
      if func:
          ret = func(url)
      else:
          ret = b'<h1>404 not found!</h1>'
      conn.send(ret)
      # 断开连接
      conn.close()

  import socket
  # 创建一个socket对象
  sk = socket.socket()
  # 绑定IP和端口
  sk.bind(('127.0.0.1', 8000))
  # 监听
  sk.listen(5)
  # 函数
  def index(url):
      with open('index.html','rb') as f:
          ret = f.read()
      return ret
  def home(url):
      ret = '<h1>home!</h1>({})'.format(url)
      return ret.encode('utf-8')
  # 定义一个list1和实际要执行的函数的对应关系
  list1 = [
      ('/index/', index),
      ('/home/', home),
  ]
  # 等待连接
  while True:
      conn, addr = sk.accept()
      # 接收数据
      data = conn.recv(1024)
      data = data.decode('utf-8')
      url = data.split()[1]
      conn.send(b'HTTP/1.1 200 OK
  
  ')
      func = None
      for i in list1:
          if url == i[0]:
              func = i[1]
              break
      if func:
          ret = func(url)
      else:
          ret = b'<h1>404 not found!</h1>'
      conn.send(ret)
      # 断开连接
      conn.close()

  import socket
  import time
  # 创建一个socket对象
  sk = socket.socket()
  # 绑定IP和端口
  sk.bind(('127.0.0.1', 8000))
  # 监听
  sk.listen(5)
  # 函数
  def index(url):
      with open('index.html', 'rb') as f:
          ret = f.read()
      return ret
  def home(url):
      ret = '<h1>home!</h1>({})'.format(url)
      return ret.encode('utf-8')
  def timer(url):
      now = time.strftime('%H:%M:%S')
      with open('time.html','r',encoding='utf-8') as f:
          data = f.read()
      data = data.replace('xxtimexx',now)
  ​
      return data.encode('utf-8')
  # 定义一个list1和实际要执行的函数的对应关系
  list1 = [
      ('/index/', index),
      ('/home/', home),
      ('/time/', timer),
  ]
  # 等待连接
  while True:
      conn, addr = sk.accept()
      # 接收数据
      data = conn.recv(1024)
      data = data.decode('utf-8')
      url = data.split()[1]
      conn.send(b'HTTP/1.1 200 OK
  
  ')
      func = None
      for i in list1:
          if url == i[0]:
              func = i[1]
              break
      if func:
          ret = func(url)
      else:
          ret = b'<h1>404 not found!</h1>'
      conn.send(ret)
      # 断开连接
      conn.close()
  补充：time.html
  
  <!DOCTYPE html>
  <html lang="en">
  <head>
      <meta charset="UTF-8">
      <title>Title</title>
  </head>
  <body>
      <h1>当前时间是：@@time@@</h1>
  </body>
  </html>

五、wsgiref

• 常用的WSGI服务器有uWSGI、Gunicorn

  • Python标准库提供的独立WSGI服务器叫wsgiref，Django开发环境用的就是这个模块来做服务器

• 简单示例：

  """  
  根据URL中不同的路径返回不同的内容--函数进阶版  
  返回HTML页面  
  让网页动态起来  
  wsgiref模块版  
  """       
  from wsgiref.simple_server import make_server     
      
  # 将返回不同的内容部分封装成函数   
  def index(url):   
      # 读取index.html页面的内容   
      with open("index.html", "r", encoding="utf8") as f:   
          s = f.read()   
      # 返回字节数据   
      return bytes(s, encoding="utf8")       
       
  def home(url):   
      with open("home.html", "r", encoding="utf8") as f:   
          s = f.read()   
      return bytes(s, encoding="utf8")       
       
  def timer(url):   
      import time   
      with open("time.html", "r", encoding="utf8") as f:   
          s = f.read()   
          s = s.replace('@@time@@', time.strftime("%Y-%m-%d %H:%M:%S"))   
      return bytes(s, encoding="utf8")        
       
  # 定义一个url和实际要执行的函数的对应关系   
  list1 = [   
      ("/index/", index),   
      ("/home/", home),   
      ("/time/", timer),   
  ]        
       
  def run_server(environ, start_response):   
      start_response('200 OK', [('Content-Type', 'text/html;charset=utf8'), ])  # 设置HTTP响应的状态码和头信息   
      url = environ['PATH_INFO']  # 取到用户输入的url   
      func = None   
      for i in list1:   
          if i[0] == url:   
              func = i[1]   
              break   
      if func:   
          response = func(url)   
      else:   
          response = b"404 not found!"   
      return [response, ]      
       
  if __name__ == '__main__':   
      httpd = make_server('127.0.0.1', 8090, run_server)   
      print("我在8090等你哦...")   
      httpd.serve_forever()  

六、jinja2

1. 模板渲染现成的工具：jinja2

   • 下载jinja2：pip install jinja2

2. 示例：

   from wsgiref.simple_server import make_server  
   from jinja2 import Template    
     
   def index(url):  
       # 读取HTML文件内容  
       with open("index2.html", "r", encoding="utf8") as f:  
           data = f.read()  
           template = Template(data)   # 生成模板文件 
           ret = template.render({'name': 'alex', 'hobby_list': ['抽烟', '喝酒', '烫头']})   # 把数据填充到模板中  
       return bytes(ret, encoding="utf8")  
     
   def home(url):  
       with open("home.html", "r", encoding="utf8") as f:  
           s = f.read()  
       return bytes(s, encoding="utf8")  
     
   # 定义一个url和实际要执行的函数的对应关系  
   list1 = [  
       ("/index/", index),  
       ("/home/", home),  
   ]   
     
   def run_server(environ, start_response):  
       start_response('200 OK', [('Content-Type', 'text/html;charset=utf8'), ])  # 设置HTTP响应的状态码和头信息  
       url = environ['PATH_INFO']  # 取到用户输入的url  
       func = None  
       for i in list1:  
           if i[0] == url:  
               func = i[1]  
               break  
       if func:  
           response = func(url)  
       else:  
           response = b"404 not found!"  
       return [response, ]  
     
   if __name__ == '__main__':  
       httpd = make_server('127.0.0.1', 8090, run_server)  
       print("我在8090等你哦...")  
       httpd.serve_forever() 

   <!DOCTYPE html>
   <html lang="zh-CN">
   <head>
       <meta charset="UTF-8">
       <meta http-equiv="x-ua-compatible" content="IE=edge">
       <meta name="viewport" content="width=device-width, initial-scale=1">
       <title>Title</title>
   </head>
   <body>
       <h1>姓名：{{name}}</h1>
       <h1>爱好：</h1>
       <ul>
           {% for hobby in hobby_list %}
               <li>{{hobby}}</li>
           {% endfor %}
       </ul>
   </body>
   </html>