Web應用

對於所有的web應用，本質上其實就是一個socket服務端，用戶的瀏覽器其實就是一個socket客戶端

import socket

def handle_request(client):

    buf = client.recv(1024)
    client.send("HTTP/1.1 200 OK\r\n\r\n".encode("utf8"))
    client.send("<h1 style=‘color:red‘>Hello, yuan</h1>".encode("utf8"))

def main():

    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.bind((
 
‘localhost‘,8001))
    sock.listen(5)

    while True:
        connection, address = sock.accept()
        handle_request(connection)
        connection.close()

if __name__ == ‘__main__‘:

    main()

最簡單的web應用就是先把HTML用文件保存好，用一個現成的HTTP服務器軟件，接受用戶請求，接受用戶請求並返回

如果要動態生成HTML，就需要把上述步驟自己來實現。不過，接受HTTP請求、解析HTTP請求、發送HTTP響應都是苦力活，如果我們自己來寫這些底層代碼，還沒開始寫動態HTML呢，就得花個把月去讀HTTP規範。

正確的做法是底層代碼由專門的服務器軟件實現，我們用Python專註於生成HTML文檔。因為我們不希望接觸到TCP連接、HTTP原始請求和響應格式，所以，需要一個統一的接口，讓我們專心用Python編寫Web業務。

這個接口就是WSGI：Web Server Gateway Interface。

wsgiref模塊

from wsgiref.simple_server import make_server


def application(environ, start_response):
    start_response(‘200 OK‘, [(‘Content-Type
 
‘, ‘text/html‘)])
    return [b‘<h1>Hello, web!</h1>‘]


httpd = make_server(‘‘, 8080, application)

print(‘Serving HTTP on port 8000...‘)
# 開始監聽HTTP請求:
httpd.serve_forever()

對比socketserver模塊

DIY一個自己的web框架

manage.py

from wsgiref.simple_server import make_server

#  request            response


from app01.views import *

from app01 import urls


def routers():

    URLpattern=urls.URLpattern

    return URLpattern


def applications(environ,start_response):

    path=environ.get("PATH_INFO")
    print("path",path)
    start_response(‘200 OK‘, [(‘Content-Type‘, ‘text/html‘),(‘Charset‘, ‘utf8‘)])

    urlpattern=routers()
    func=None

    for item in urlpattern:
        if path==item[0]:
            func=item[1]
            break

    if func:
        return [func(environ)]
    else:
        return [b"<h1>404!<h1>"]


    # return [b"<h1>hello world<h1>"]


if __name__ == ‘__main__‘:

    t=make_server("",8810,applications)
    print("server is working...")
    t.serve_forever()

urls

from app01.views import *


URLpattern = (
    ("/login/", login),
)

views

import pymysql

from urllib.parse import parse_qs


def login(request):

    if request.get("REQUEST_METHOD")=="POST":
        print("+++++",request)


        #當請求方式是GET時
        # user_union,pwd_union=request.get("QUERY_STRING").split("&")
        # _,user=user_union.split("=")
        # _,pwd=pwd_union.split("=")

        # 環境變量 CONTENT_LENGTH 可能是空值 或者 值丟失
        try:
            request_body_size = int(request.get(‘CONTENT_LENGTH‘, 0))
        except (ValueError):
            request_body_size = 0
        # 當請求方式是POST時, 變量將會被放在存在域wsgi.input文件中的HTTP請求信息中, 由WSGI 服務器一起發送.
        request_body = request[‘wsgi.input‘].read(request_body_size)
        d = parse_qs(request_body)


        user=d.get(b"user")[0].decode("utf8")
        pwd=d.get(b"pwd")[0].decode("utf8")

        print("user",user,pwd)


        #連接數據庫
        conn = pymysql.connect(host=‘‘,port= 3306,user = ‘root‘,passwd=‘‘,db=‘s6‘) #db：庫名
        #創建遊標
        cur = conn.cursor()

        SQL="select * from userinfo2 WHERE NAME =‘%s‘ AND PASSWORD =‘%s‘"%(user,pwd)

        cur.execute(SQL)

        if cur.fetchone():

            f=open("templates/backend.html","rb")

            data=f.read()
            data=(data.decode("utf8"))%user
            return data.encode("utf8")

        else:
             return b"user or pwd is wrong"


    else:
        f = open("templates/login.html", "rb")

        data = f.read()
        f.close()

        return data

models

import pymysql


import pymysql
#連接數據庫
conn = pymysql.connect(host=‘‘,port= 3306,user = ‘root‘,passwd=‘‘,db=‘s6‘) #db：庫名
#創建遊標
cur = conn.cursor()

# sql=‘‘‘
# create table userinfo2(
#         id INT PRIMARY KEY ,
#         name VARCHAR(32) ,
#         password VARCHAR(32)
# )
#
# ‘‘‘
#
# cur.execute(sql)
#
# cur.executemany("insert into userinfo2 values(%s,%s,%s)", [(1,"yuan","123"),
#                                                           (2,"alex","456"),
#                                                           (3,"egon","789")])


cur.execute("select * from userinfo2 WHERE NAME=‘yuan‘ AND PASSWORD =‘123‘")
#提交
conn.commit()
#關閉指針對象
cur.close()
#關閉連接對象
conn.close()

web應用與web框架（Day65）