Web框架

Web 框架

对于所有的Web应用，本质上其实就是一个socket服务端，用户的浏览器其实就是一个socket客户端。

实例

#!/usr/bin/env python
# coding:utf-8
import socket

def handle_request(client):
    buf = client.recv(1024)
    client.send("HTTP/1.1 200 OK

".encode())
    client.send("Hello, Seven".encode())

def main():
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.bind(('localhost', 8000))
    sock.listen(5)
    while True:
        connection, address = sock.accept()
        handle_request(connection)
        connection.close()


if __name__ == '__main__':
    main()

WSGI

WSGI（Web Server Gateway Interface）是一种规范，它定义了使用python编写的web app与web server之间接口格式，实现web app与web server间的解耦。

python标准库提供的独立WSGI服务器称为wsgiref。

from wsgiref.simple_server import make_server


def RunServer(environ, start_response):
    start_response('200 OK', [('Content-Type', 'text/html')])
    return [bytes('<h1>Hello, web!</h1>', encoding='utf-8'), ]


if __name__ == '__main__':
    httpd = make_server('', 8000, RunServer)
    print("Serving HTTP on port 8000...")
    httpd.serve_forever()

自定义框架

实例

通过python标准库提供的wsgiref模块开发一个自己的Web框架

#!/usr/bin/env python
# coding:utf-8
from wsgiref.simple_server import make_server

def index():
    return ['<H1>index</H1>'.encode(),]

def login():
    return ['<H1>login<H1>'.encode(),]

def routers():
    urlpatterns = (
        ('/index/', index),
        ('/login/', login),
    )
    return urlpatterns

def RunServer(environ, start_response):
    start_response('200 OK', [('Content-Type', 'text/html')])
    url = environ['PATH_INFO']
    print(url)
    urlpatterns = routers()
    func = None
    for item in urlpatterns:
        if item[0] == url:
            func = item[1]
            break
    if func:
        return func()
    else:
        return ['404 not found'.encode(),]

if __name__ == '__main__':
    httpd = make_server('localhost', 8000, RunServer)
    print("Serving HTTP on port 8000...")
    httpd.serve_forever()

模板替换

对于所有的login、index均返回给用户浏览器一个简单的字符串，在现实的Web请求中一般会返回一个复杂的符合HTML规则的字符串，所以我们一般将要返回给用户的HTML写在指定文件中，然后再返回。

使用开源工具jinja2，遵循其指定语法，可以实现对HTML文本替换

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
    <h1>{{name}}</h1>

    <ul>
        {% for item in user_list %}
        <li>{{item}}</li>
        {% endfor %}
    </ul>

</body>
</html>

server

#!/usr/bin/env python
# -*- coding:utf-8 -*-
 
from wsgiref.simple_server import make_server
from jinja2 import Template
 
 
def index():
    # return 'index'
 
    # template = Template('Hello {{ name }}!')
    # result = template.render(name='John Doe')
 
    f = open('index.html')
    result = f.read()
    template = Template(result)
    data = template.render(name='John Doe', user_list=['alex', 'eric'])
    return data.encode('utf-8')
 
 
def login():
    # return 'login'
    f = open('login.html')
    data = f.read()
    return data
 
 
def routers():
 
    urlpatterns = (
        ('/index/', index),
        ('/login/', login),
    )
 
    return urlpatterns
 
 
def run_server(environ, start_response):
    start_response('200 OK', [('Content-Type', 'text/html')])
    url = environ['PATH_INFO']
    urlpatterns = routers()
    func = None
    for item in urlpatterns:
        if item[0] == url:
            func = item[1]
            break
    if func:
        return func()
    else:
        return '404 not found'
 
 
if __name__ == '__main__':
    httpd = make_server('', 8000, run_server)
    print "Serving HTTP on port 8000..."
    httpd.serve_forever()

WEB框架模型

MVC‘

Model：数据库
View：模板文件
Controller：业务处理

MTV

Model：数据库
Template：模板文件
View：业务处理