Python 利用三个简易模块熟悉前后端交互流程

准备工作

　　 在学习Django之前，先动手撸一个简单的WEB框架来熟悉一下前后端交互的整体流程

　　 本次用到的模块：

　　 1.wsgiref，这是一个Python自带的模块，用于构建路由与视图

　　 2.pymysql，第三方模块，用于数据库与视图层进行数据交互

　　 3.jinja2，第三方模块，用于对前端页面进行模板渲染

　　 请使用pip install modulename进行安装

　　 如果安装jinja2失败，请使用easy_install Jinja2命令进行安装

数据交互

　　 其实前面已经有大量的地方讨论浏览器与后端服务器如何进行交互，也用socket进行实现过简单的交互，但是我们需要在前者基础上做一个优化，即用户在地址栏输入什么路径，就返回请求的路径名字。

　　 当这个需求完成后，我们就可以根据不同的请求路径，返回出不同的HTML文档信息，但是使用原生的socket这个过程会十分的繁琐，所以用一次就放弃吧。

from socket import *

def run():
    server = socket(AF_INET, SOCK_STREAM)  # 传输层基于TCP协议
    server.bind(("127.0.0.1", 8080))
    server.listen(5)

    while 1:

        conn, addr = server.accept()
        try:  # 防止Windows平台下Client端异常关闭导致双向链接崩塌Server端异常的情况发生
            data = conn.recv(1024)
            if not data:  # bug修复：针对类UNIX环境
                continue
                
            request_path = data.decode("utf-8").split(" ")[1] # 拿到请求的路径
            conn.sendall(bytes("HTTP/1.1 201 OK 

", "utf8"))  # 返回响应头
            conn.sendall(bytes("<h1>{0}</h1>".format(request_path), "utf8"))  # 返回响应体
            
        except Exception:
            continue

    conn.close()

if __name__ == '__main__':
    run()

　　 socket

wsgiref

　　 以下是利用wsgiref实现上面的功能，简单了许多，并且代码变得更加明了。

　　 此外新增加了访问路径不存在时给出404错误提示。

from wsgiref.simple_server import make_server

def index(request):
    return "You visited index"

def login(request):
    return "You visited login"

def error(request):
    return "404 Resource request error"

urls = [
    ("/index", index),
    ("/login", login),
]

def run(request, response):

    """
    request:① 请求相关的所有数据
    response：② 响应相关的数据
    return：③  返回给浏览器的数据
    """

    response("200 OK",[]) # 响应首行，响应头
    func = None
    request_path = request.get("PATH_INFO") # 拿到路径

    for url in urls:
        if request_path == url[0]:
            func = url[1]
            break # 匹配到后结束for循环

    if func:
        res = func(request)
    else:
        res = error(request)

    return [res.encode("utf-8")]

if __name__ == '__main__':
    server = make_server("localhost", 8080, run)
    # ③ 实时监听127.0.0.1:8080地址，只要有链接请求，都交给run函数处理
    server.serve_forever() # ④ 开启服务

　　 wsgiref

代码解耦

　　 我们对上述代码进行解耦，将不同功能的代码放在不同的文件夹下。

　　

-- webproject
	-- view # 视图相关代码
		-- view.py
	-- urls # 路由相关代码
		-- urls.py
	-- run.py # 启动相关代码

# view.py

def index(request):
    return "You visited index"

def login(request):
    return "You visited login"

def error(request):
    return "404 Resource request error"

# urls.py

from view.view import *

urls = [
    ("/index", index),
    ("/login", login),
]


# run.py

from wsgiref.simple_server import make_server
from urls.urls import *

def run(request, response):
    
    """
    request:① 请求相关的所有数据
    response：② 响应相关的数据
    return：③  返回给浏览器的数据
    """

    response("200 OK",[]) # 响应首行，响应头
    func = None
    request_path = request.get("PATH_INFO") # 拿到路径

    for url in urls:
        if request_path == url[0]:
            func = url[1]
            break # 匹配到后结束for循环

    if func:
        res = func(request)
    else:
        res = error(request)

    return [res.encode("utf-8")]

if __name__ == '__main__':
    server = make_server("localhost", 8080, run)
    # ③ 实时监听127.0.0.1:8080地址，只要有链接请求，都交给run函数处理
    server.serve_forever() # ④ 开启服务

返回页面

　　 继续上面的流程，已经将代码进行解耦了，此时我们新建一个template文件夹用于专门存放返回的网页。

　　 并在该文件夹下新建index.html以及login.html

-- webproject
	-- view # 视图相关代码
		-- view.py
	-- urls # 路由相关代码
		-- urls.py
	-- template # 前端页面
		-- index.html
		-- login.html
	-- run.py # 启动相关代码

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <script src='https://cdn.bootcdn.net/ajax/libs/jquery/3.5.1/jquery.js'></script>
    <link rel='stylesheet' href='https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap.min.css'
        integrity='sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u' crossorigin='anonymous'>
    <script src='https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/js/bootstrap.min.js'
        integrity='sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa'
        crossorigin='anonymous'></script>
    <title>Document</title>
    <style>
        
        .carousel .item {
            height: 400px;
            background-color: #777;
        }

        .carousel-inner>.item>img {
            position: absolute;
            top: 0;
            left: 0;
            min-width: 100%;
            height: 100%;
        }
    </style>
</head>

<body>

    <nav class="navbar navbar-inverse">
        <div class="container-fluid">
            <!-- Brand and toggle get grouped for better mobile display -->
            <div class="navbar-header">
                <button type="button" class="navbar-toggle collapsed" data-toggle="collapse"
                    data-target="#bs-example-navbar-collapse-1" aria-expanded="false">
                    <span class="sr-only">Toggle navigation</span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                </button>
                <a class="navbar-brand" href="#">INDEX</a>
            </div>

            <!-- Collect the nav links, forms, and other content for toggling -->
            <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
                <form class="navbar-form navbar-left">
                    <div class="form-group">
                        <input type="text" class="form-control" placeholder="Search">
                    </div>
                    <button type="submit" class="btn btn-default">Submit</button>
                </form>
                <ul class="nav navbar-nav navbar-right">
                    <li><a href="HTTP://127.0.0.1:8080/login">LOGIN</a></li>
                    <li><a href="#">REGISTER</a></li>
                </ul>
            </div><!-- /.navbar-collapse -->
        </div><!-- /.container-fluid -->
    </nav>


    <div class="container-fluid">

        <div class="row">
            <div class="col-xs-12 col-sm-12 col-md-12 col-lg-12 input-lg-5g bg-primar ">
                <div class="page-header">
                    <h1>Example page header <small>Subtext for header</small></h1>
                </div>
            </div>

            <div class="col-xs-3 col-sm-3 col-md-3 col-lg-3">
                <div class="list-group">
                    <a href="#" class="list-group-item active">
                        Cras justo odio
                    </a>
                    <a href="#" class="list-group-item">Dapibus ac facilisis in</a>
                    <a href="#" class="list-group-item">Morbi leo risus</a>
                    <a href="#" class="list-group-item">Porta ac consectetur ac</a>
                    <a href="#" class="list-group-item">Vestibulum at eros</a>
                </div>
            </div>

            <div class="col-xs-9 col-sm-9 col-md-9 col-lg-9">
                <div id="carousel-example-generic" class="carousel slide" data-ride="carousel">
                    <!-- Indicators -->
                    <ol class="carousel-indicators">
                        <li data-target="#carousel-example-generic" data-slide-to="0" class="active"></li>
                        <li data-target="#carousel-example-generic" data-slide-to="1"></li>
                    </ol>

                    <!-- Wrapper for slides -->
                    <div class="carousel-inner">
                        <div class="item active">
                            <img src="https://tse4-mm.cn.bing.net/th/id/OIP._PbxAuEi3ce9S1DtQ3KilwHaEK?w=306&h=180&c=7&o=5&dpr=1.25&pid=1.7"
                                alt="...">
                        </div>
                        <div class="item">
                            <img src="https://tse2-mm.cn.bing.net/th/id/OIP.Det5e8us-qsNAGEhnL6u0AHaF7?w=238&h=190&c=7&o=5&dpr=1.25&pid=1.7"
                                alt="...">
                        </div>
                    </div>

                    <!-- Controls -->
                    <a class="left carousel-control" href="#carousel-example-generic" role="button" data-slide="prev">
                        <span class="glyphicon glyphicon-chevron-left" aria-hidden="true"></span>
                        <span class="sr-only">Previous</span>
                    </a>
                    <a class="right carousel-control" href="#carousel-example-generic" role="button" data-slide="next">
                        <span class="glyphicon glyphicon-chevron-right" aria-hidden="true"></span>
                        <span class="sr-only">Next</span>
                    </a>
                </div>
            </div>

        </div>

    </div>

</body>

</html>
index.html
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src='https://cdn.bootcdn.net/ajax/libs/jquery/3.5.1/jquery.js'></script>
    <link rel='stylesheet' href='https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap.min.css'
        integrity='sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u' crossorigin='anonymous'>
    <script src='https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/js/bootstrap.min.js'
        integrity='sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa'
        crossorigin='anonymous'></script>

    <style>
        body {
            display: flex;
            justify-content: center;
            align-self: center;
            height: 100vh;
            background-color: rebeccapurple;

        }

        form.form1 {
            display: flex;
            flex-flow: column;
            justify-content: center;
            align-self: center;
            border: 1px solid #ddd;
            padding: 10px;
            width: 30%;
            background-color: white;
            border-radius: 15px;
        }
    </style>

</head>

<body>



    <form class="form1" action="#">
        <div class="form-group">
            <label for="exampleInputEmail1">username</label>
            <input type="email" class="form-control" id="exampleInputEmail1" placeholder="please enter user name">
        </div>
        <div class="form-group">
            <label for="exampleInputPassword1">Password</label>
            <input type="password" class="form-control" id="exampleInputPassword1"
                placeholder="please enter user password">
        </div>

        <button type="submit" class="btn btn-default" disabled>Submit</button>
    </form>


</body>

</html>
login.html

　　 除此之外，还要将视图中index函数与login函数的返回结果改一下

# view.py

def index(request):
    with open(file="template/index.html",mode="r",encoding="utf-8") as f:
        res = f.read()
    return res

def login(request):
    with open(file="template/login.html",mode="r",encoding="utf-8") as f:
        res = f.read()
    return res

def error(request):
    return "404 Resource request error"
view.py

　　 那么目前，我们的框架已经初具雏形了，能够根据请求路径的不同返回不同的HTML文档。

pymsql

　　 继续接着做逻辑，点击login后输入用户名和密码提交完应该对数据库进行验证，判断该用户是否存在。

　　 那么现在我们就需要用到pymysql模块了，还是新建一个文件夹叫db，然后创建db文件进行操作。

import pymysql


class DbServer(object):
    def __init__(self):
        self.conn = pymysql.connect(
            host="localhost",
            database="db1",
            charset="utf8mb4",
            user="root",
            cursorclass=pymysql.cursors.DictCursor,  # 记录结果，字典显示
            autocommit=True,  # 自动提交
        )

        self.cursor = self.conn.cursor()

    def select(self, sql, val=None):
        res = self.cursor.execute(sql, val)
        return res, self.cursor.fetchone()  # 返回查找行数，查找结果

    def insert(self, sql, val=None):
        pass

    def drop(self, sql, val=None):
        pass

    def deletle(self, sql, val=None):
        pass

    def __del__(self):
        # 关闭程序前关闭链接与游标
        self.cursor.close()
        self.conn.close()

if __name__ != '__main__': # 不能当作独立文件进行运行
    dbserver = DbServer()
db.py

　　 记得在数据库中先插入数据

create table user(
    id INT PRIMARY KEY AUTO_INCREMENT,
    name CHAR(12) NOT NULL,
    password CHAR(12) NOT NULL,
    INDEX(name) -- 添加索引
);

INSERT INTO  user(name,password) VALUES
    ("Yunya","123456");
MySQL命令

　　 别忘了在view.py中进行导入，与此同时，还要写一个验证功能。

from db.db import dbserver
import jinja2

def index(request):
    with open(file="template/index.html", mode="r", encoding="utf-8") as f:
        res = f.read()
    return res


def login(request):
    with open(file="template/login.html", mode="r", encoding="utf-8") as f:
        res = f.read()
    return res


def login_verif(request):
    # GET 请求  QUERY_STRING
    request_msg = request.get("QUERY_STRING", None).split("&")
    user_dict = {}

    for msg in request_msg:
        key, value = msg.split("=")
        user_dict[key] = value
    from db.db import dbserver

    def index(request):
        with open(file="template/index.html", mode="r", encoding="utf-8") as f:
            res = f.read()
        return res

    def login(request):
        with open(file="template/login.html", mode="r", encoding="utf-8") as f:
            res = f.read()
        return res

def login_verif(request):
    # GET 请求  QUERY_STRING
    request_msg = request.get("QUERY_STRING", None).split("&")
    user_dict = {}

    for msg in request_msg:
        key, value = msg.split("=")
        user_dict[key] = value

    sql = "select * from user where name=%s and password = %s"
    val = (user_dict.get("username"), user_dict.get("password"))
    result = dbserver.select(sql, val)
    if result[0]:
        return "Welcome" + result[1].get("name")
    else:
        return "Login failed, no such user"

def error(request):
    return "404 Resource request error"
view.py

　　 还要在urls.py文件中增加验证的路由解析。

from view.view import *

urls = [
    ("/index", index),
    ("/login", login),
    ("/login_verif", login_verif),
]
urls.py

　　 最后一步修改前端login.html中的form提交路径

  <form class="form1" action="http://127.0.0.1:8080/login_verif">
        <div class="form-group">
            <label for="username">username</label>
            <input type="text" id="username" name="username" class="form-control" placeholder="please enter user name">
        </div>
        <div class="form-group">
            <label for="password">Password</label>
            <input type="password" id="password" name="password" class="form-control"
                placeholder="please enter user password">
        </div>

        <button type="submit" class="btn btn-default">Submit</button>
    </form>
login.html

jinja2

　　 在验证完成后，我们应该根据用户名与密码是否正确来返回不同的内容。

　　 这个时候可以使用jinja2的模板语言了。

　　 首先在Template文件夹下新建一个verification.html做验证

　　 然后修改一下view中的login_verif代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
    <div class="container">
        
        <div class="row">
            <div class="col-xs-6 col-sm-6 col-md-6 col-lg-6 col-xs-offset-3 col-sm-offset-3 col-md-offset-3  col-lg-offset-3 ">
                <div class="page-header">
                    {% if login_msg.status %}
                        <h1>欢迎回家{{login_msg.username}}</h1>
                    {% else %}
                        <h1>无此用户！请检查用户名或密码是否输入正确</h1>
                    {% endif %}
                  </div>
            </div>
        </div>
        
    </div>
    

</body>
</html>
verification.html
def login_verif(request):
    # GET 请求  QUERY_STRING
    request_msg = request.get("QUERY_STRING", None).split("&")
    user_dict = {}

    for msg in request_msg:
        key, value = msg.split("=")
        user_dict[key] = value

    sql = "select * from user where name=%s and password = %s"
    val = (user_dict.get("username"), user_dict.get("password"))
    result = dbserver.select(sql, val)

    with open("./template/verification.html","r",encoding="utf-8") as f:
        data = f.read()

    tmp = jinja2.Template(data) # 做成模板

    if result[0]:
        msg = {"username":result[1].get("name"),"status":1}
       
    else:
        msg = {"username":None,"status":0}

    res = tmp.render(login_msg=msg) # 模板中添加变量
    return res
view.py def login_verif

成果演示

代码总和

　　 db - db.py

import pymysql


class DbServer(object):
    def __init__(self):
        self.conn = pymysql.connect(
            host="localhost",
            database="db1",
            charset="utf8mb4",
            user="root",
            cursorclass=pymysql.cursors.DictCursor,  # 记录结果，字典显示
            autocommit=True,  # 自动提交
        )

        self.cursor = self.conn.cursor()

    def select(self, sql, val=None):
        res = self.cursor.execute(sql, val)
        return res, self.cursor.fetchone()  # 返回查找行数，查找结果

    def insert(self, sql, val=None):
        pass

    def drop(self, sql, val=None):
        pass

    def deletle(self, sql, val=None):
        pass

    def __del__(self):
        # 关闭程序前关闭链接与游标
        self.cursor.close()
        self.conn.close()

if __name__ != '__main__':
    dbserver = DbServer()
View Code

　　 template - index.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <script src='https://cdn.bootcdn.net/ajax/libs/jquery/3.5.1/jquery.js'></script>
    <link rel='stylesheet' href='https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap.min.css'
        integrity='sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u' crossorigin='anonymous'>
    <script src='https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/js/bootstrap.min.js'
        integrity='sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa'
        crossorigin='anonymous'></script>
    <title>Document</title>
    <style>
        
        .carousel .item {
            height: 400px;
            background-color: #777;
        }

        .carousel-inner>.item>img {
            position: absolute;
            top: 0;
            left: 0;
            min-width: 100%;
            height: 100%;
        }
    </style>
</head>

<body>

    <nav class="navbar navbar-inverse">
        <div class="container-fluid">
            <!-- Brand and toggle get grouped for better mobile display -->
            <div class="navbar-header">
                <button type="button" class="navbar-toggle collapsed" data-toggle="collapse"
                    data-target="#bs-example-navbar-collapse-1" aria-expanded="false">
                    <span class="sr-only">Toggle navigation</span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                </button>
                <a class="navbar-brand" href="#">INDEX</a>
            </div>

            <!-- Collect the nav links, forms, and other content for toggling -->
            <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
                <form class="navbar-form navbar-left">
                    <div class="form-group">
                        <input type="text" class="form-control" placeholder="Search">
                    </div>
                    <button type="submit" class="btn btn-default">Submit</button>
                </form>
                <ul class="nav navbar-nav navbar-right">
                    <li><a href="HTTP://127.0.0.1:8080/login">LOGIN</a></li>
                    <li><a href="#">REGISTER</a></li>
                </ul>
            </div><!-- /.navbar-collapse -->
        </div><!-- /.container-fluid -->
    </nav>


    <div class="container-fluid">

        <div class="row">
            <div class="col-xs-12 col-sm-12 col-md-12 col-lg-12 input-lg-5g bg-primar ">
                <div class="page-header">
                    <h1>Example page header <small>Subtext for header</small></h1>
                </div>
            </div>

            <div class="col-xs-3 col-sm-3 col-md-3 col-lg-3">
                <div class="list-group">
                    <a href="#" class="list-group-item active">
                        Cras justo odio
                    </a>
                    <a href="#" class="list-group-item">Dapibus ac facilisis in</a>
                    <a href="#" class="list-group-item">Morbi leo risus</a>
                    <a href="#" class="list-group-item">Porta ac consectetur ac</a>
                    <a href="#" class="list-group-item">Vestibulum at eros</a>
                </div>
            </div>

            <div class="col-xs-9 col-sm-9 col-md-9 col-lg-9">
                <div id="carousel-example-generic" class="carousel slide" data-ride="carousel">
                    <!-- Indicators -->
                    <ol class="carousel-indicators">
                        <li data-target="#carousel-example-generic" data-slide-to="0" class="active"></li>
                        <li data-target="#carousel-example-generic" data-slide-to="1"></li>
                    </ol>

                    <!-- Wrapper for slides -->
                    <div class="carousel-inner">
                        <div class="item active">
                            <img src="https://tse4-mm.cn.bing.net/th/id/OIP._PbxAuEi3ce9S1DtQ3KilwHaEK?w=306&h=180&c=7&o=5&dpr=1.25&pid=1.7"
                                alt="...">
                        </div>
                        <div class="item">
                            <img src="https://tse2-mm.cn.bing.net/th/id/OIP.Det5e8us-qsNAGEhnL6u0AHaF7?w=238&h=190&c=7&o=5&dpr=1.25&pid=1.7"
                                alt="...">
                        </div>
                    </div>

                    <!-- Controls -->
                    <a class="left carousel-control" href="#carousel-example-generic" role="button" data-slide="prev">
                        <span class="glyphicon glyphicon-chevron-left" aria-hidden="true"></span>
                        <span class="sr-only">Previous</span>
                    </a>
                    <a class="right carousel-control" href="#carousel-example-generic" role="button" data-slide="next">
                        <span class="glyphicon glyphicon-chevron-right" aria-hidden="true"></span>
                        <span class="sr-only">Next</span>
                    </a>
                </div>
            </div>

        </div>

    </div>

</body>

</html>
View Code

　　 template - login.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src='https://cdn.bootcdn.net/ajax/libs/jquery/3.5.1/jquery.js'></script>
    <link rel='stylesheet' href='https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap.min.css'
        integrity='sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u' crossorigin='anonymous'>
    <script src='https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/js/bootstrap.min.js'
        integrity='sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa'
        crossorigin='anonymous'></script>

    <style>
        body {
            display: flex;
            justify-content: center;
            align-self: center;
            height: 100vh;
            background-color: rebeccapurple;

        }

        form.form1 {
            display: flex;
            flex-flow: column;
            justify-content: center;
            align-self: center;
            border: 1px solid #ddd;
            padding: 10px;
            width: 30%;
            background-color: white;
            border-radius: 15px;
        }
    </style>

</head>

<body>



    <form class="form1" action="http://127.0.0.1:8080/login_verif">
        <div class="form-group">
            <label for="username">username</label>
            <input type="text" id="username" name="username" class="form-control" placeholder="please enter user name">
        </div>
        <div class="form-group">
            <label for="password">Password</label>
            <input type="password" id="password" name="password" class="form-control"
                placeholder="please enter user password">
        </div>

        <button type="submit" class="btn btn-default">Submit</button>
    </form>


</body>

</html>
View Code

　　 template - verifcation.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
    <div class="container">
        
        <div class="row">
            <div class="col-xs-6 col-sm-6 col-md-6 col-lg-6 col-xs-offset-3 col-sm-offset-3 col-md-offset-3  col-lg-offset-3 ">
                <div class="page-header">
                    {% if login_msg.status %}
                        <h1>欢迎回家{{login_msg.username}}</h1>
                    {% else %}
                        <h1>无此用户！请检查用户名或密码是否输入正确</h1>
                    {% endif %}
                  </div>
            </div>
        </div>
        
    </div>
    
</body>
</html>
View Code

　　 urls - urls.py

from view.view import *

urls = [
    ("/index", index),
    ("/login", login),
    ("/login_verif", login_verif),
]
View Code

　　 view - view.py

from db.db import dbserver
import jinja2

def index(request):
    with open(file="template/index.html", mode="r", encoding="utf-8") as f:
        res = f.read()
    return res


def login(request):
    with open(file="template/login.html", mode="r", encoding="utf-8") as f:
        res = f.read()
    return res


def login_verif(request):
    # GET 请求  QUERY_STRING
    request_msg = request.get("QUERY_STRING", None).split("&")
    user_dict = {}

    for msg in request_msg:
        key, value = msg.split("=")
        user_dict[key] = value
    from db.db import dbserver

    def index(request):
        with open(file="template/index.html", mode="r", encoding="utf-8") as f:
            res = f.read()
        return res

    def login(request):
        with open(file="template/login.html", mode="r", encoding="utf-8") as f:
            res = f.read()
        return res

def login_verif(request):
    # GET 请求  QUERY_STRING
    request_msg = request.get("QUERY_STRING", None).split("&")
    user_dict = {}

    for msg in request_msg:
        key, value = msg.split("=")
        user_dict[key] = value

    sql = "select * from user where name=%s and password = %s"
    val = (user_dict.get("username"), user_dict.get("password"))
    result = dbserver.select(sql, val)

    with open("./template/verification.html","r",encoding="utf-8") as f:
        data = f.read()

    tmp = jinja2.Template(data)

    if result[0]:
        msg = {"username":result[1].get("name"),"status":1}
       
    else:
        msg = {"username":None,"status":0}

    res = tmp.render(login_msg=msg) # 返回登录信息 
    return res

def error(request):
    return "404 Resource request error"
View Code

　　 run.py

from wsgiref.simple_server import make_server
from urls.urls import *

def run(request, response):
   
    """
    request:① 请求相关的所有数据
    response：② 响应相关的数据
    return：③  返回给浏览器的数据
    """

    response("200 OK",[]) # 响应首行，响应头
    func = None
    request_path = request.get("PATH_INFO") # 拿到路径

    for url in urls:
        if request_path == url[0]:
            func = url[1]
            break # 匹配到后结束for循环

    if func:
        res = func(request)
    else:
        res = error(request)

    return [res.encode("utf-8")]

if __name__ == '__main__':
    server = make_server("localhost", 8080, run)
    # ③ 实时监听127.0.0.1:8080地址，只要有链接请求，都交给run函数处理
    server.serve_forever() # ④ 开启服务
View Code

最后结论

　　 其实通过这三个基础模块，相信你已经了解了其基本的流程，但是用这三个模块来做成一个建议的Web框架还是存在大量的不足。

　　 1.HTML文件代码冗余过度

　　 2.提交全部为GET方式，这使得密码等传输极度不安全

　　 3.原生SQL语句操纵数据库，开发效率偏低

　　 4.路由的URL解析太过死板，不能灵活解析

　　 这些不足点在Django框架中都会有非常好的解决方案，因此Django框架是学习PythonWeb的首选。

　　 总之前后端交互的大体流程就是这样，前端给请求路径，后端根据路径查询数据库中数据并进行处理后返回HTML文档再由模板语言进行解析（前后端不分离），最终呈现出一个完整的动态页面。

　　 当然还有很多知识点没有涉及到，如cookie，ajax，权限管理等等，这些都会在之后慢慢做介绍。

【推广】 免费学中医，健康全家人
原文地址：https://www.cnblogs.com/Yunya-Cnblogs/p/13628192.html