自定义web框架

web应用本质上就是一个socket服务端，浏览器是socket客户端，基于请求做出响应，客户都先请求，服务端做出对应的响应，按照http协议的请求协议发送请求，服务端按照http协议的响应协议来响应请求，这样的网络通信，我们就可以自己实现Web框架了。

准备一个html文件

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>测试页面</title>
</head>
<body>
<h1>标题1</h1>
<img src="https://iproute.cn/images/logo.png" alt="头像">
</body>
</html>

编写python的socket服务端

import socket
sk = socket.socket()
sk.bind(('127.0.0.1',8080))
sk.listen()
conn,addr = sk.accept()
b_msg = conn.recv(1024)
str_msg = b_msg.decode('utf-8')
conn.send(b'HTTP/1.1 200 ok \r\n\r\n')
conn.send(b'hello')
conn.close()
sk.close()

运行服务端之后，浏览器访问http://127.0.0.1:8080 ，浏览器传给socket的内容如下

GET / HTTP/1.1   # 请求行，其中的/是路径
Host: 127.0.0.1:8080
Connection: keep-alive
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.116 Safari/537.36
Sec-Fetch-Dest: document
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Sec-Fetch-Site: none
Sec-Fetch-Mode: navigate
Sec-Fetch-User: ?1
Accept-Encoding: gzip, deflate, br
Accept-Language: zh-CN,zh;q=0.9,zh-TW;q=0.8
Cookie: smid=sys4OxpO9GZqFqSAA37ZAWOnLB54KsilDWWuipaewHYE9ggajIeWtlHRrIBuSZyR038Q7r4c2XNUXdfdWR-I4A; APP_HOST=http%3A//127.0.0.1%3A49153/; HOST=http%3A//127.0.0.1%3A49153/; kodUserLanguage=zh-CN; kodUserID=1; X-CSRF-TOKEN=i9YQRqWXnS4Iy3uRt3vW; p_h5_u=057F0CAB-3644-4539-A2BC-249B82EA9934

修改socket服务端，让其返回网页内容

import socket
sk = socket.socket()
sk.bind(('127.0.0.1',8080))
sk.listen()
conn,addr = sk.accept()
b_msg = conn.recv(1024)
str_msg = b_msg.decode('utf-8')
print(str_msg)
conn.send(b'HTTP/1.1 200 ok \r\n\r\n')
with open('test.html','rb') as f:
    f_data = f.read()
conn.send(f_data)
conn.close()
sk.close()

这样就可以将网页内容返回给浏览器了

如果想要在网页中携带本地路径的图片，那么修改html代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>测试页面</title>
</head>
<body>
<h1>标题1</h1>
<img src="logo.png" alt="头像">
</body>
</html>

然后修改socket服务端

import socket
sk = socket.socket()
sk.bind(('127.0.0.1',8080))
sk.listen()
while 1:    # 浏览器多次访问，所以需要while
    conn,addr = sk.accept()
    b_msg = conn.recv(1024)
    str_msg = b_msg.decode('utf-8')
    path = str_msg.split('\r\n')[0].split(' ')[1]
    print('path>>>',path)
    conn.send(b'HTTP/1.1 200 ok \r\n\r\n')
    if path == '/':
        with open('test.html','rb') as f:
            f_data = f.read()
        conn.send(f_data)
        conn.close()    # HTTP协议是短链接的，一次请求对应一次响应，这个请求就结束了，所以我们需要写上close，不然浏览器自己断了
    elif path == '/logo.png':
        with open('logo.png','rb') as f:
            f_data = f.read()
        conn.send(f_data)
        conn.close()
sk.close()

可以改成使用函数的版本

import socket
sk = socket.socket()
sk.bind(('127.0.0.1',8080))
sk.listen()
def func1(conn):
    with open('test.html', 'rb') as f:
        f_data = f.read()
    conn.send(f_data)
    conn.close()
def func2(conn):
    with open('logo.png', 'rb') as f:
        f_data = f.read()
    conn.send(f_data)
    conn.close()

while 1:
    conn,addr = sk.accept()
    b_msg = conn.recv(1024)
    str_msg = b_msg.decode('utf-8')
    path = str_msg.split('\r\n')[0].split(' ')[1]
    print('path>>>',path)
    conn.send(b'HTTP/1.1 200 ok \r\n\r\n')
    if path == '/':
        func1(conn)
    elif path == '/logo.png':
        func2(conn)
sk.close()

现在还不支持高并发的情况，可以加上多线程

import socket
from threading import Thread

sk = socket.socket()
sk.bind(('127.0.0.1',8080))
sk.listen()
def func1(conn):
    with open('test.html', 'rb') as f:
        f_data = f.read()
    conn.send(f_data)
    conn.close()
def func2(conn):
    with open('logo.png', 'rb') as f:
        f_data = f.read()
    conn.send(f_data)
    conn.close()

while 1:
    conn,addr = sk.accept()
    b_msg = conn.recv(1024)
    str_msg = b_msg.decode('utf-8')
    path = str_msg.split('\r\n')[0].split(' ')[1]
    print('path>>>',path)
    conn.send(b'HTTP/1.1 200 ok \r\n\r\n')
    if path == '/':
        t = Thread(target=func1,args=(conn,))
        t.start()
    elif path == '/logo.png':
        t = Thread(target=func2,args=(conn,))
        t.start()
sk.close()

替换字符串，实现不同的时间访问返回时间戳模拟动态内容

在网页中，用特殊的符号@@666@@表示需要被替换掉的地方，修改html代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>测试页面</title>
</head>
<body>
<h1>标题1</h1>
<img src="logo.png" alt="头像">
<h2>@@666@@</h2>
</body>
</html>

修改socket服务端

import socket
from threading import Thread
import time

sk = socket.socket()
sk.bind(('127.0.0.1',8080))
sk.listen()
def func1(conn):
    with open('test.html', 'r',encoding="utf-8") as f:
        f_data = f.read()
        now = str(time.time())
        f_data = f_data.replace("@@666@@",now).encode('utf-8')
    conn.send(f_data)
    conn.close()
def func2(conn):
    with open('logo.png', 'rb') as f:
        f_data = f.read()
    conn.send(f_data)
    conn.close()

while 1:
    conn,addr = sk.accept()
    b_msg = conn.recv(1024)
    str_msg = b_msg.decode('utf-8')
    path = str_msg.split('\r\n')[0].split(' ')[1]
    print('path>>>',path)
    conn.send(b'HTTP/1.1 200 ok \r\n\r\n')
    if path == '/':
        t = Thread(target=func1,args=(conn,))
        t.start()
    elif path == '/logo.png':
        t = Thread(target=func2,args=(conn,))
        t.start()
sk.close()

WSGI

WSGI（Web Server Gateway Interface）是一种规范，它定义了使用Python编写的web应用程序与web服务器程序之间的接口格式，实现web应用程序与web服务器程序间的解耦。

常用的WSGI服务器有uwsgi、Gunicorn。而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。

模板渲染JinJa2

上面的过程中用@@666@@替换了动态的内容， 其实模板渲染有个现成的工具： jinja2

安装jinja2

pip install jinja2

编写html文件

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>jinja2</title>
</head>
<body>
    <h1>姓名：</h1>
    <h1>爱好：</h1>
    <ul>

    </ul>
</body>
</html>

编写wsgi服务端

from wsgiref.simple_server import make_server
from jinja2 import Template

def index():
    with open("index.html", "r", encoding='utf-8') as f:
        data = f.read()
    template = Template(data)
    ret = template.render({"name":"CS", "hobby_list":["抽烟"，"喝酒","烫头"]})
    return [bytes(ret, encoding="utf-8"),]

URL_LIST = [
    ("/index/", index),
]

def run_server(environ, start_response)
    start_response('200 OK', [('Content-Type', 'text/html;charset=utf8'),])
    url = environ['PATH_INFO']
    func = None
    for i in URL_LIST:
        if i[0] == url:
            func = i[1]
            break
    if func:
        return func()
    else:
        return [bytes("404没有该页面", encoding="utf8"),]

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

下面演示从数据库中提取内容进行替换

CREATE TABLE user(
  id int auto_increment PRIMARY KEY,
  name CHAR(10) NOT NULL,
  hobby CHAR(20) NOT NULL
)engine=innodb DEFAULT charset=UTF8;

INSERT into user (name, hobby) VALUES ('CS', '抽烟,喝酒,烫头');

SELECT * FROM user;

修改socket服务端

import pymysql
from wsgiref.simple_server import make_server
from jinja2 import Template

def index(name,hobby):
    with open("index.html", "r", encoding='utf-8') as f:
        data = f.read()
    template = Template(data)
    ret = template.render({"name":name, "hobby_list":hobby})
    return [bytes(ret, encoding="utf-8"),]

URL_LIST = [
    ("/index/", index),
]

def run_server(environ, start_response):
    conn = pymysql.connect(
        host="127.0.0.1",
        port=3306,
        user="root",
        passwd="test123",
        db="pywebdb",
        charset="utf8"
    )
    cursor = conn.cursor()
    cursor.execute('select * from user')
    data = cursor.fetchone()
    name=data[1]
    hobby=data[2]
    conn.close()
    start_response('200 OK', [('Content-Type', 'text/html;charset=utf8'),])
    url = environ['PATH_INFO']
    func = None
    for i in URL_LIST:
        if i[0] == url:
            func = i[1]
            break
    if func:
        return func(name,hobby)
    else:
        return [bytes("404没有该页面", encoding="utf8"),]

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

模板的原理就是字符串替换，我们只要在HTML页面中遵循jinja2的语法规则写上，其内部就会按照指定的语法进行相应的替换，从而达到动态的返回内容。

学前沿IT，到英格科技! all right reserved，powered by Gitbook本文发布时间： 2025-04-15 20:07:17

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