059.Python前端Django组件cooki和session

D先生 2020-04-09

一 会话跟踪技术

1.1 什么是会话

会话是指一个终端用户(服务器)与交互系统(客户端)进行通讯的过程。

1.2 什么是会话跟踪

对同一个用户对服务器的连续的请求和接受响应的监视。(将用户与同一用户发出的不同请求之间关联,为了数据共享)

1.3 为什么需要会话跟踪

浏览器与服务器之间的通信是通过HTTP协议进行通信的,而HTTP协议是”无状态”的协议,它不能保存客户的信息,即一次响应完成之后连接就断开了,下一次的请求需要重新连接,这样就需要判断是否是同一个用户,所以才应会话跟踪技术来实现这种要求

在一个会话的多个请求中共享数据,这就是会话跟踪技术。例如在一个会话中的请求如下: 请求银行主页; 

  • 请求登录(请求参数是用户名和密码);
  • 请求转账(请求参数与转账相关的数据); 
  • 请求信用卡还款(请求参数与还款相关的数据)。

1.4 会话路径技术使用Cookie或session完成 

我们知道HTTP协议是无状态协议,也就是说每个请求都是独立的!无法记录前一次请求的状态。但HTTP协议中可以使用Cookie来完成会话跟踪!在Web开发中,使用session来完成会话跟踪,session底层依赖Cookie技术。 

Cookie是可以被禁止的。

二 COOKIE的使用

2.1 Cookie规范

  • Cookie大小上限为4KB; 
  •  一个服务器最多在客户端浏览器上保存20个Cookie; 
  •  一个浏览器最多保存300个Cookie;  

2.2 Cookie与HTTP头 

Cookie是通过HTTP请求和响应头在客户端和服务器端传递的: 

  • Cookie:请求头,客户端发送给服务器端; 
  • 格式:Cookie: a=A; b=B; c=C。即多个Cookie用分号离开; ? Set-Cookie:响应头,服务器端发送给客户端; 
  • 一个Cookie对象一个Set-Cookie: Set-Cookie: a=A Set-Cookie: b=B Set-Cookie: c=C   

2.3 Cookie的覆盖

如果服务器端发送重复的Cookie那么会覆盖原有的Cookie,例如客户端的第一个请求服务器端发送的Cookie是:Set-Cookie: a=A;第二请求服务器端发送的是:Set-Cookie: a=AA,那么客户端只留下一个Cookie,即:a=AA。

django中的cookie语法

2.4 使用Cookie

创建一个数据库

mysql> create database cookie_test default charset=utf8;

mysql> use cookie_test;

新建一个项目

:~/PycharmProjects# django-admin startproject cookie_seesion

:~/PycharmProjects# cd cookie_seesion

:~/PycharmProjects/cookie_seesion# python3 manage.py startapp cookie

:~/PycharmProjects/cookie_seesion# vim cookie_seesion/settings.py

INSTALLED_APPS = [
    ‘django.contrib.admin‘,
    ‘django.contrib.auth‘,
    ‘django.contrib.contenttypes‘,
    ‘django.contrib.sessions‘,
    ‘django.contrib.messages‘,
    ‘django.contrib.staticfiles‘,
    ‘cookie.apps.CookieConfig‘
]

配置数据库

DATABASES = {
    ‘default‘: {
        ‘ENGINE‘: ‘django.db.backends.mysql‘,
        ‘NAME‘: ‘cookie_test‘,
        ‘HOST‘: ‘127.0.0.1‘,
        ‘PORT‘: 3306,
        ‘USER‘: ‘root‘,
        ‘PASSWORD‘:‘123456‘,
    }
}

只想数据库迁移操作

:~/PycharmProjects/cookie_seesion# python3 manage.py makemigrations

:~/PycharmProjects/cookie_seesion# python3 manage.py migrate

Operations to perform:
  Apply all migrations: admin, auth, contenttypes, sessions
Running migrations:
  Applying contenttypes.0001_initial... OK
  Applying auth.0001_initial... OK
  Applying admin.0001_initial... OK
  Applying admin.0002_logentry_remove_auto_add... OK
  Applying admin.0003_logentry_add_action_flag_choices... OK
  Applying contenttypes.0002_remove_content_type_name... OK
  Applying auth.0002_alter_permission_name_max_length... OK
  Applying auth.0003_alter_user_email_max_length... OK
  Applying auth.0004_alter_user_username_opts... OK
  Applying auth.0005_alter_user_last_login_null... OK
  Applying auth.0006_require_contenttypes_0002... OK
  Applying auth.0007_alter_validators_add_error_messages... OK
  Applying auth.0008_alter_user_username_max_length... OK
  Applying auth.0009_alter_user_last_name_max_length... OK
  Applying auth.0010_alter_group_name_max_length... OK
  Applying auth.0011_update_proxy_permissions... OK
  Applying sessions.0001_initial... OK

查看数据库

mysql> show tables;

059.Python前端Django组件cooki和session

 配置路由分发

from django.contrib import admin
from django.urls import path,include

urlpatterns = [
    path(‘admin/‘, admin.site.urls),
    path("cookie/",include("cookie.urls"))
]

cookie/urls

from django.urls import  path,re_path
from cookie import views
urlpatterns = [
    path("index/",views.index),
    path("login/",views.login),
]

当url文件把[] 写成{}时,会有如下错误

059.Python前端Django组件cooki和session

views视图文件

from django.shortcuts import render,redirect

# Create your views here.
def index(request):
    return render(request,"index.html")
def login(request):
    if request.method == "GET":
        return  render(request,"login.html")
    else:
        username = request.POST.get("username")
        password = request.POST.get("password")
        if username == "joy" and password == "123456":
            return redirect("/cookie/index/")
        else:
            return redirect("/cookie/login/")

模板文件

:~/PycharmProjects/cookie_seesion# mkdir templates

TEMPLATES = [
    {
        ‘BACKEND‘: ‘django.template.backends.django.DjangoTemplates‘,
        ‘DIRS‘: [os.path.join(BASE_DIR,"templates")],
        ‘APP_DIRS‘: True,
        ‘OPTIONS‘: {
            ‘context_processors‘: [
                ‘django.template.context_processors.debug‘,
                ‘django.template.context_processors.request‘,
                ‘django.contrib.auth.context_processors.auth‘,
                ‘django.contrib.messages.context_processors.messages‘,
            ],
        },
    },
]

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h3>index 页面。。。</h3>

</body>
</html>

login.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h3>用户登录</h3>
<form action="" method="POST">
    {% csrf_token %}
    <p>用户名:<input type="text" name="username"></p>
    <p>密 码:<input type="password" name="password"></p>
    <input type="submit">
</form>

</body>
</html>

访问http://127.0.0.1:8000/cookie/index/

059.Python前端Django组件cooki和session

 访问http://127.0.0.1:8000/cookie/login并登陆

059.Python前端Django组件cooki和session

会得到index页面

但是这样的话,直接访问http://127.0.0.1:8000/cookie/index/也会得到index.html页面

添加一个cookie

from django.shortcuts import render,redirect

# Create your views here.
def index(request):
    return render(request,"index.html")
def login(request):
    if request.method == "GET":
        return  render(request,"login.html")
    else:
        username = request.POST.get("username")
        password = request.POST.get("password")
        if username == "joy" and password == "123456":
            rep = redirect("/cookie/index/")
            rep.set_cookie("is_login",True)
            return rep
        else:
            return redirect("/cookie/login/")

直接访问

059.Python前端Django组件cooki和session

登录访问

059.Python前端Django组件cooki和session

携带有is_login的cookie

做登陆限制

from django.shortcuts import render,redirect

# Create your views here.
def index(request):
    if not request.COOKIES.get("is_login"):
        return redirect("/cookie/login/")
    return render(request,"index.html")
def login(request):
    if request.method == "GET":
        return  render(request,"login.html")
    else:
        username = request.POST.get("username")
        password = request.POST.get("password")
        if username == "joy" and password == "123456":
            rep = redirect("/cookie/index/")
            rep.set_cookie("is_login",True)
            return rep
        else:
            return redirect("/cookie/login/")

这样cookie保存在本地,也可以直接访问

cookie注销页面

from django.urls import  path,re_path
from cookie import views
urlpatterns = [
    path("index/",views.index),
    path("login/",views.login),
    path(‘loginout/‘,views.loginout),
]

views页面

from django.shortcuts import render,redirect

# Create your views here.
def index(request):
    if not request.COOKIES.get("is_login"):
        return redirect("/cookie/login/")
    return render(request,"index.html")
def login(request):
    if request.method == "GET":
        return  render(request,"login.html")
    else:
        username = request.POST.get("username")
        password = request.POST.get("password")
        if username == "joy" and password == "123456":
            rep = redirect("/cookie/index/")
            rep.set_cookie("is_login",True)
            return rep
        else:
            return redirect("/cookie/login/")
def loginout(request):
    rep = redirect("/cookie/login/")
    rep.delete_cookie("is_login")
    return rep

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h3>index 页面。。。</h3>
<a href="/cookie/loginout/">注销</a>
</body>
</html>

059.Python前端Django组件cooki和session 

点击注销

059.Python前端Django组件cooki和session

再次直接访问index,就不能得到index页面

添加一个订单页面

from django.urls import  path,re_path
from cookie import views
urlpatterns = [
    path("index/",views.index),
    path("login/",views.login),
    path(‘loginout/‘,views.loginout),
    path(‘order/‘,views.order),
]

view页面

from django.shortcuts import render,redirect,HttpResponse

# Create your views here.
def index(request):
    if not request.COOKIES.get("is_login"):
        return redirect("/cookie/login/")
    return render(request,"index.html")
def login(request):
    if request.method == "GET":
        return  render(request,"login.html")
    else:
        username = request.POST.get("username")
        password = request.POST.get("password")
        if username == "joy" and password == "123456":
            rep = redirect("/cookie/index/")
            rep.set_cookie("is_login",True)
            return rep
        else:
            return redirect("/cookie/login/")
def loginout(request):
    rep = redirect("/cookie/login/")
    rep.delete_cookie("is_login")
    return rep
def order(request):
    if not request.COOKIES.get("is_login"):
        return redirect("/cookie/login/")
    return HttpResponse("oreder success")

使用装饰器进行改进

from django.shortcuts import render,redirect,HttpResponse

# Create your views here.#装饰器
def login_required(func):
    def inner(request,*args,**kwargs):
        if not request.COOKIES.get("is_login"):
            return redirect("/cookie/login/")
        rep = func(request,*args,**kwargs)
        return rep
    return inner

@login_required
def index(request):
#    if not request.COOKIES.get("is_login"):
#        return redirect("/cookie/login/")
    return render(request,"index.html")
def login(request):
    if request.method == "GET":
        return  render(request,"login.html")
    else:
        username = request.POST.get("username")
        password = request.POST.get("password")
        if username == "joy" and password == "123456":
            rep = redirect("/cookie/index/")
            rep.set_cookie("is_login",True)
            return rep
        else:
            return redirect("/cookie/login/")
def loginout(request):
    rep = redirect("/cookie/login/")
    rep.delete_cookie("is_login")
    return rep

@login_required
def order(request):
#    if not request.COOKIES.get("is_login"):
#        return redirect("/cookie/login/")
    return HttpResponse("oreder success")

三 Seesion的使用

3.1 session简介

Session是服务器端技术,利用这个技术,服务器在运行时可以 为每一个用户的浏览器创建一个其独享的session对象,由于 session为用户浏览器独享,所以用户在访问服务器的web资源时 ,可以把各自的数据放在各自的session中,当用户再去访问该服务器中的其它web资源时,其它web资源再从用户各自的session中 取出数据为用户服务。 

django初始化数据库的时候,会有一个django_session的表

 059.Python前端Django组件cooki和session

3.2 session和浏览器

1.浏览器向服务器发送请求时,第一次的cookie是空的,如果在视图里配置request.session["username"]="joy",则会

生成一个session_key的随机字符串,相当于一把钥匙,

2.会把request的键值对存到session-data里面

3.把随机生成的seesion_key设成一个cookie。seesionid=session_key这样的形式,挡浏览器第二次请求的时候,就会携带这个session_id作为cookie

3.3 django中session语法

1、设置Sessions值
          request.session[‘session_name‘] ="admin"
2、获取Sessions值
          session_name = request.session["session_name"]
3、删除Sessions值
          del request.session["session_name"]
4、flush()
     删除当前的会话数据并删除会话的Cookie。
     这用于确保前面的会话数据不可以再次被用户的浏览器访问
5、get(key, default=None)
fav_color = request.session.get(‘fav_color‘, ‘red‘)
6、pop(key)
fav_color = request.session.pop(‘fav_color‘)
7、keys()
8、items()
9、setdefault()
10 用户session的随机字符串
        request.session.session_key
  
        # 将所有Session失效日期小于当前日期的数据删除
        request.session.clear_expired()
  
        # 检查 用户session的随机字符串 在数据库中是否
        request.session.exists("session_key")
  
        # 删除当前用户的所有Session数据
        request.session.delete("session_key")
  
        request.session.set_expiry(value)
            * 如果value是个整数,session会在些秒数后失效。
            * 如果value是个datatime或timedelta,session就会在这个时间后失效。
            * 如果value是0,用户关闭浏览器session就会失效。
            * 如果value是None,session会依赖全局session失效策略。

3.4 通过seedion实现一个用户登录管理

创建一个session 的app

:~/PycharmProjects/cookie_seesion# python3 manage.py startapp session

注册app

INSTALLED_APPS = [
    ‘django.contrib.admin‘,
    ‘django.contrib.auth‘,
    ‘django.contrib.contenttypes‘,
    ‘django.contrib.sessions‘,
    ‘django.contrib.messages‘,
    ‘django.contrib.staticfiles‘,
    ‘cookie.apps.CookieConfig‘,
    ‘session.apps.SessionConfig‘,
]

urls配置路由分发

from django.contrib import admin
from django.urls import path,include

urlpatterns = [
    path(‘admin/‘, admin.site.urls),
    path("cookie/",include("cookie.urls")),
    path("session/",include("session.urls")),
]

url文件

from django.urls import  path,re_path
from session import views
urlpatterns = [
    path("index/",views.index),
    path(‘login/‘,views.login),
]

view文件

from django.shortcuts import render,HttpResponse,redirect

# Create your views here.
def index(request):
    if not request.session.get("is_login"):      #1. 从cookie中取出sessionid        #2. 拿到随机字符串到django_session 表中过滤对象      #3. 拿到对象取出data值。
        return redirect("/session/login/")
    return render(request,"session_index.html")
def login(request):
    if request.method == "GET":
        return  render(request,"login.html")
    else:
        username = request.POST.get("username")
        password = request.POST.get("password")
        if username == "joy" and password == "123456":
            request.session["is_login"] = True      #1. 生产随机字符串      #2. 将数据存到django_session表中      #3. 设置cookie值。(sessionid,值为随机字符串)
            return redirect("/session/index/")
        else:
            return redirect("/cookie/login/")

访问http://127.0.0.1:8000/session/index,会直接返回http://127.0.0.1:8000/session/login/

059.Python前端Django组件cooki和session

登录得到cookie值

059.Python前端Django组件cooki和session

查看数据库

 mysql> select * from django_session;

059.Python前端Django组件cooki和session

默认过期时间是两周

注销登录,清除seedion值

from django.urls import  path,re_path
from session import views
urlpatterns = [
    path("index/",views.index),
    path(‘login/‘,views.login),
    path(‘logout/‘,views.logout),
]

views文件

from django.shortcuts import render,HttpResponse,redirect

# Create your views here.
def index(request):
    if not request.session.get("is_login"):
        return redirect("/session/login/")
    return render(request,"session_index.html")
def login(request):
    if request.method == "GET":
        return  render(request,"login.html")
    else:
        username = request.POST.get("username")
        password = request.POST.get("password")
        if username == "joy" and password == "123456":
            request.session["is_login"] = True
            return redirect("/session/index/")
        else:
            return redirect("/cookie/login/")
def logout(request):
    request.session.flush()
    """
    1. 从cookie中取出sessionid
    2. 拿到随机字符串到django_session 表中过滤对象
    3. 删除该对象。
    """
    return redirect("/session/login/")

seesiin_index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h3>session index 页面。。。</h3>
<a href="/session/logout">注销</a>
</body>
</html>

注销后,查看数据库信息,session被清空

059.Python前端Django组件cooki和session

查看数据库

059.Python前端Django组件cooki和session

3.5 session保存的是浏览器的信息验证

实例验证

from django.shortcuts import render,HttpResponse,redirect

# Create your views here.
def index(request):
    if not request.session.get("is_login"):
        return redirect("/session/login/")
    return render(request,"session_index.html")
def login(request):
    if request.method == "GET":
        return  render(request,"login.html")
    else:
        username = request.POST.get("username")
        password = request.POST.get("password")
        if username in ["joy","john"] and password == "123456":
            request.session["is_login"] = True
            return redirect("/session/index/")
        else:
            return redirect("/cookie/login/")
def logout(request):
    request.session.flush()
    """
    1. 从cookie中取出sessionid
    2. 拿到随机字符串到django_session 表中过滤对象
    3. 删除该对象。
    """
    return redirect("/session/login/")

在同一个浏览器,登录joy账号

059.Python前端Django组件cooki和session

 059.Python前端Django组件cooki和session

数据库信息

059.Python前端Django组件cooki和session

在同一个浏览器,打开另一个窗口,登录john账号

059.Python前端Django组件cooki和session

059.Python前端Django组件cooki和session

查看数据库

059.Python前端Django组件cooki和session

并没有变化,同样的操作,但是当使用无痕浏览器登录john账号, 

结果如下

059.Python前端Django组件cooki和session

 059.Python前端Django组件cooki和session

数据库,不同的浏览器,session不一样

059.Python前端Django组件cooki和session

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