Django之web框架的本质
前言
由上一篇HTTP协议，我们简单的知道HTTP那点事儿。但是我们的目的是在此基础上编写web程序。所以，接下来通过一个个示例了解，web框架的本质——通俗的说，web框架封装了socket、数据库操作、路由分发、模板配置等，留给我们现成的接口，让我们更专注业务逻辑本身。
一个简单的web示例
import socket
# 1. 创建socket对象
sk = socket.socket()
# 2. 绑定IP和端口
sk.bind((\'127.0.0.1\', 8888))
# 3. 监听
sk.listen(5)
# 4. 循环监听
while 1:
conn, addr = sk.accept() # 等待连接
received_data = conn.recv(8192) # 接收数据
print(received_data) # b\'GET / HTTP/1.1\r\nHost: 127.0.0.1:8888\r\nConnection: keep-alive\r\nUpgrade-Insecure-Requests: 1\r\nUser-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36\r\nAccept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3\r\nAccept-Encoding: gzip, deflate, br\r\nAccept-Language: zh-CN,zh;q=0.9,en;q=0.8\r\nCookie: csrftoken=FQW7H4SEVPRqdqIr4vSeiP3EdjX2C0JY7VwCdmXevoXcPjiAMBtNptkiZLHqXo4d\r\n\r\n\'
conn.send(b\'HTTP/1.1 200 OK\r\n\r\n\') # 接收数据
conn.send(b\'<h1>Successful</h1>\')
conn.close() # 关闭连接
现在，使用浏览器地址栏访问http://127.0.0.1:8888/，就会得到Successful。
根据不同路径返回不同内容
第一版·普通版
import socket
# 创建socket对象
sk = socket.socket()
# 绑定IP和端口
sk.bind((\'127.0.0.1\', 8888))
# 监听
sk.listen()
while True:
# 等待连接
conn, addr = sk.accept()
# 接收数据
data = conn.recv(8192)
data = data.decode(\'utf-8\')
url = data.split()[1]
print(url)
# 返回状态行
conn.send(b\'HTTP/1.1 200 OK\r\n\r\n\')
if url == \'/oumei\':
conn.send(b\'<h1>oumei</h1>\')
elif url == \'/rihan\':
conn.send(b\'<h1>rihan</h1>\')
else:
conn.send(b\'<h1>404</h1>\')
# 关闭连接
conn.close()
第二版·函数版
import socket
# 创建socket对象
sk = socket.socket()
# 绑定IP和端口
sk.bind((\'127.0.0.1\', 8888))
# 监听
sk.listen()
def oumei(url):
ret = \'oumei - {}\'.format(url)
return ret.encode(\'utf-8\')
def rihan(url):
ret = \'rihan//// - {}\'.format(url)
return ret.encode(\'utf-8\')
while True:
# 等待连接
conn, addr = sk.accept()
# 接收数据
data = conn.recv(8192)
data = data.decode(\'utf-8\')
url = data.split()[1]
print(url)
# 返回状态行
conn.send(b\'HTTP/1.1 200 OK\r\n\r\n\')
if url == \'/oumei\':
ret = oumei(url)
elif url == \'/rihan\':
ret = rihan(url)
else:
ret = b\'404 not found\'
conn.send(ret)
# 关闭连接
conn.close()
第三版·函数进阶版
import socket
# 创建socket对象
sk = socket.socket()
# 绑定IP和端口
sk.bind((\'127.0.0.1\', 8888))
# 监听
sk.listen()
def oumei(url):
ret = \'oumei - {}\'.format(url)
return ret.encode(\'utf-8\')
def rihan(url):
ret = \'rihan//// - {}\'.format(url)
return ret.encode(\'utf-8\')
def guochan(url):
ret = \'guochan - {}\'.format(url)
return ret.encode(\'utf-8\')
list = [
(\'/oumei\', oumei),
(\'/rihan\', rihan),
(\'/guochan\', guochan),
]
while True:
# 等待连接
conn, addr = sk.accept()
# 接收数据
data = conn.recv(8192)
data = data.decode(\'utf-8\')
url = data.split()[1]
print(url)
# 返回状态行
conn.send(b\'HTTP/1.1 200 OK\r\n\r\n\')
func = None
for i in list:
if i[0] == url:
func = i[1]
break
if func:
ret = func(url)
else:
ret = b\'404 not found\'
conn.send(ret)
# 关闭连接
conn.close()
第四版·反射版
ps：仅针对当前脚本使用的反射。
import socket
sk = socket.socket()
sk.bind(("127.0.0.1", 8888))
sk.listen()
class Server(object):
""" 模拟多个页面 """
def europe(self):
return "<h1>europe</h1>".encode(\'utf8\')
def kkc(self):
return "<h1>kkc</h1>".encode(\'utf8\')
def notfond(self):
return "<h1>404 not fond</h1>".encode(\'utf8\')
while 1:
# 等待请求
conn, address = sk.accept()
# 获取数据
data = conn.recv(8192).decode(\'utf8\')
# 处理请求拿到请求路径
# print(data)
url = data.split(\' \', 2)[1][1:]
# print(url, data)
# 返回数据
server_obj = Server()
if hasattr(server_obj, url):
res = getattr(server_obj, url)()
else:
res = server_obj.notfond()
conn.send(b\'HTTP/1.1 200 OK\r\n\r\n\')
conn.send(res)
conn.close()
返回HTML页面
首先在同级目录有个index.html页面：
<!DOCTYPE html>
<html lang="en">
<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>index page</h1>
</body>
</html>
然后写server端：
import socket
# 创建socket对象
sk = socket.socket()
# 绑定IP和端口
sk.bind((\'127.0.0.1\', 8888))
# 监听
sk.listen()
def oumei(url):
ret = \'oumei - {}\'.format(url)
return ret.encode(\'utf-8\')
def rihan(url):
ret = \'rihan//// - {}\'.format(url)
return ret.encode(\'utf-8\')
def guochan(url):
ret = \'guochan - {}\'.format(url)
return ret.encode(\'utf-8\')
def index(url):
with open(\'index.html\', \'rb\') as f:
ret = f.read()
return ret
list = [
(\'/oumei\', oumei),
(\'/rihan\', rihan),
(\'/guochan\', guochan),
(\'/index\', index),
]
while True:
# 等待连接
conn, addr = sk.accept()
# 接收数据
data = conn.recv(8192)
data = data.decode(\'utf-8\')
url = data.split()[1]
print(url)
# 返回状态行
conn.send(b\'HTTP/1.1 200 OK\r\n\r\n\')
func = None
for i in list:
if i[0] == url:
func = i[1]
break
if func:
ret = func(url)
else:
ret = b\'404 not found\'
conn.send(ret)
# 关闭连接
conn.close()
返回动态页面
在同级目录有个tiem.html页面：
<!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>
在来实现代码：
import socket
import time
# 创建socket对象
sk = socket.socket()
# 绑定IP和端口
sk.bind((\'0.0.0.0\', 8000))
# 监听
sk.listen()
def oumei(url):
ret = \'oumei - {}\'.format(url)
return ret.encode(\'utf-8\')
def rihan(url):
ret = \'rihan//// - {}\'.format(url)
return ret.encode(\'utf-8\')
def guochan(url):
ret = \'guochan - {}\'.format(url)
return ret.encode(\'utf-8\')
def index(url):
with open(\'index.html\', \'rb\') as f:
ret = f.read()
return ret
def timer(url):
now = time.strftime(\'%Y-%m-%d %H:%M:%S\')
with open(\'time.html\', \'r\', encoding=\'utf-8\') as f:
data = f.read()
data = data.replace(\'@@time@@\', now)
return data.encode(\'utf-8\')
list = [
(\'/oumei\', oumei),
(\'/rihan\', rihan),
(\'/guochan\', guochan),
(\'/index\', index),
(\'/time\', timer),
]
while True:
# 等待连接
conn, addr = sk.accept()
# 接收数据
data = conn.recv(8096)
data = data.decode(\'utf-8\')
url = data.split()[1]
print(url)
# 返回状态行
conn.send(b\'HTTP/1.1 200 OK\r\n\r\n\')
func = None
for i in list:
if i[0] == url:
func = i[1]
break
if func:
ret = func(url)
else:
ret = b\'404 not found\'
conn.send(ret)
# 关闭连接
conn.close()
总结
正如文章开始所示，web框架本质就是一个socket服务端。
web框架功能：
- socket收发消息
- 根据不同的路径返回不同的内容
- 可以返回动态页面（使用字符串替换等方式进行模板渲染）
Python中主流web框架：
欢迎斧正，that\’s all
see also：[简说Python Web异步框架](https://www.yuanrenxue.com/tricks/introduce-python-asynchronous-framework.html)
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