Django学习铺垫

Web框架本质

所有的web服务本质都是一个socket服务端，用户浏览器就是一个socket客户端，这样就实现了自己的web框架 ，但是自己的写的框架肯定很low，各种工能崩溃，所以我们就要学习python强大的Django 框架

首先我们要自己一步步写一个框架，用来辅助理解Django的原理

import socket
import time

sk = socket.socket()
sk.bind(("127.0.0.1", 8080))  # 绑定IP和端口
sk.listen()  # 监听

# 将返回不同的内容部分封装成函数
def index(url):
    with open("index.html", "r", encoding="utf8") as f:
        s = f.read()
        now = str(time.time())
        s = s.replace("@@oo@@", now)
    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")

# 定义一个url和实际要执行的函数的对应关系
list1 = [
    ("/index/", index),
    ("/home/", home),
]

while 1:
    # 等待连接
    conn, add = sk.accept()
    data = conn.recv(8096)  # 接收客户端发来的消息
    # 从data中取到路径
    data = str(data, encoding="utf8")  # 把收到的字节类型的数据转换成字符串
    # 按\r\n分割
    data1 = data.split("\r\n")[0]
    url = data1.split()[1]
    print("url:", url)
    print("*" * 120)
    # \r\n是换行；Content-Type:是响应类型格式 ；text/html 表示网页
    # HTTP/1.1 200 OK 所用的协议
    conn.send(b'HTTP/1.1 200 OK\r\nContent-Type: text/html; charset=utf-8\r\n\r\n')  # 因为要遵循HTTP协议
    # 根据不同的路径返回不同内容
    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!"

    # 具体的响应体
    conn.send(response)
    conn.close()

wsgiref

WSGI（Web Server Gateway Interface）就是一种规范，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

import time
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):
    with open("index.html", "r", encoding="utf8") as f:
        s = f.read()
        now = str(time.time())
        s = s.replace("@@oo@@", now)
    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")

# 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("Serving HTTP on port 8090...")
    httpd.serve_forever()

wsgiref

jinja2
HTML模板渲染数据,本质上就是HTML内容中利用一些特殊的符号来替换要展示的数据。 我这里用的特殊符号是我定义的，其实模板渲染有个现成的工具： jinja2

首先安装：pip install jinja2

import time
from wsgiref.simple_server import make_server
import jinja2

# 将返回不同的内容部分封装成函数
def index(url):
    with open("index.html", "r", encoding="utf8") as f:
        s = f.read()
        now = str(time.time())
        s = s.replace("@@oo@@", now)
    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 xiaoqiang(url):
    with open("xiaoqiang.html", "r", encoding="utf8") as f:
        s = f.read()
        template = jinja2.Template(s)  # 生成一个jinja2的Template（模板）对象
        data = {"name": "小强", "hobby_list": ["对子哈特", "姑娘", "大汉"]}
        response = template.render(data)  # 本质上是完成了字符串的替换
    return bytes(response, 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),
    ("/xiaoqiang/", xiaoqiang),
]

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("Serving HTTP on port 8090...")
    httpd.serve_forever()

jinja2

现在的数据是我们自己手写的，我们也可以从数据库中查询数据

使用pymysql连接数据库：

conn = pymysql.connect(host="127.0.0.1", port=3306, user="root", passwd="xxx", db="xxx", charset="utf8")
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
cursor.execute("select name, age, department_id from userinfo")
user_list = cursor.fetchall()
cursor.close()
conn.close()

连接数据库

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

# 将返回不同的内容部分封装成函数
def index(url):
    with open("index.html", "r", encoding="utf8") as f:
        s = f.read()
        now = str(time.time())
        s = s.replace("@@oo@@", now)
    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 xiaoqiang(url):
    with open("xiaoqiang.html", "r", encoding="utf8") as f:
        s = f.read()
        template = jinja2.Template(s)  # 生成一个jinja2的Template（模板）对象
        # data = {"name": "小强", "hobby_list": ["对子哈特", "姑娘", "大汉"]}

        conn = pymysql.connect(host="127.0.0.1", port=3306, user="root", passwd="", db="userinfo", charset="utf8")
        cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
        cursor.execute("SELECT name, hobby FROM user")
        user = cursor.fetchone()
        cursor.close()
        conn.close()
        print("user:", user)
        print("*" * 120)

        hobby_list = user["hobby"].split()
        user["hobby_list"] = hobby_list
        print(user)
        print("-" * 120)
        response = template.render(user)  # 本质上是完成了字符串的替换
    return bytes(response, 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),
    ("/xiaoqiang/", xiaoqiang),
]

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("Serving HTTP on port 8090...")
    httpd.serve_forever()