# HTTP的请求头和响应头
浏览器与服务器通信，主要是依靠请求报文来向服务器表示想要获取到什么样的资源，服务器会用响应报文来表达服务器会员的数据的情况
# 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
```html
测试页面
标题1
```
编写python的socket服务端
```python
import socket
sk = socket.socket()
# 允许地址复用
sk.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7
Accept-Encoding: gzip, deflate, br, zstd
Accept-Language: zh-CN,zh;q=0.9,zh-TW;q=0.8
Cache-Control: max-age=0
Connection: keep-alive
Host: 127.0.0.1:8080
Sec-Fetch-Dest: document
Sec-Fetch-Mode: navigate
Sec-Fetch-Site: none
Sec-Fetch-User: ?1
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36
sec-ch-ua: "Google Chrome";v="131", "Chromium";v="131", "Not_A Brand";v="24"
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: "macOS"
```
修改socket服务端，让其返回网页内容
```python
import socket
sk = socket.socket()
# 允许地址复用
sk.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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
```html
测试页面
标题1
```
然后修改socket服务端
```python
import socket
sk = socket.socket()
# 允许地址复用
sk.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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
```python
import socket
sk = socket.socket()
# 允许地址复用
sk.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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
```python
import socket
from threading import Thread
sk = socket.socket()
# 允许地址复用
sk.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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
```html
测试页面
标题1
@@666@@
```
修改socket服务端
```python
import socket
from threading import Thread
import time
sk = socket.socket()
# 允许地址复用
sk.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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`
```bash
pip install jinja2 -i https://pypi.tuna.tsinghua.edu.cn/simple
```
编写html文件
```html
jinja2
姓名：{{name}}
爱好：
{% for hobby in hobby_list %}
- {{hobby}}
{% endfor %}
```
编写wsgi服务端
```python
from wsgiref.simple_server import make_server
from jinja2 import Template
def index():
with open("test.html", "r", encoding='utf-8') as f:
data = f.read()
template = Template(data)
ret = template.render({"name": "张三", "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
- mysql点此下载：https://www.123865.com/s/BKNfTd-WDXKA提取码:6666
```sql
-- 创建数据库
create database pywebdb;
-- 进入数据库中
use pywebdb
-- 创建表
CREATE TABLE user(
id int auto_increment PRIMARY KEY,
name CHAR(10) NOT NULL,
hobby CHAR(20) NOT NULL
)engine=innodb DEFAULT charset=UTF8;
-- 插入一个数据
INSERT into user (name, hobby) VALUES ('张三', '抽烟,喝酒,烫头');
-- 查看插入的数据
SELECT * FROM user;
```
修改socket服务端
```python
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。