python---django请求-响应的生命周期（FBV和CBV含义）
Django请求的生命周期是指：当用户在访问该url路径是，在服务器Django后台都发生了什么。
客户端发送Http请求给服务端，Http请求是一堆字符串,其内容是：
访问：http://crm.oldboy.com:8080/login.html，客户端发送Http请求
1.路由映射，匹配路由（从上到下，匹配到就停止），对应相应views中的业务函数
url(r'^login.html', views.login),
2.匹配成功后，执行views下的对应函数：（FBV）
def login(req): print('req.body',req.body) print("GET",req.GET) message='' if req.method == "POST": print(req.body) print(req.POST) user = req.POST.get("username") pwd = req.POST.get("password") count = models.Administrator.objects.filter(username=user,password=pwd).count() if count: red = redirect("/index.html") timeout = datetime.datetime.now()+datetime.timedelta(seconds=3) red.set_cookie('username',user,expires=timeout) return red else: message = "用户名或密码错误" return render(req,"login.html",{'msg':message})
URL --> 函数 ====> FBV(Function-based views) 基于函数的视图
URL --> 类 ====> CBV (Class-based views) 基于类的视图
FBV：在Django中使用较多，在其他框架中多使用CBV，例如tornado,还有PHP的多种框架等
Django中CBV使用：
首先需要设置views中的类：
from django.views import View class CBV(View):
#根据请求头中的request method进行自动执行get和post def get(self,request): return render(request,"cbv_login.html") def post(self,request): return HttpResponse("<h1>cbv_post</h1>")
然后修改urls文件路由：
urlpatterns = [ url(r"cbv",views.CBV.as_view()) ]
模板文件：
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <form action="/cbv" method="post"> {% csrf_token %} <div> <label for="user">用户名：</label> <input type="text" id="user" name="username"/> </div> <div> <label for="pwd">密码：</label> <input type="password" id="pwd" name="password"/> </div> <div> <label></label> <input type="submit" value="登录"> <label>{{ msg }}</label> </div> </form> </body> </html>
使用url访问默认是get方式，显示cbv_login.html页面，提交页面，进入post页面，显示cbv_post数据
get还是post，是由于请求头中的Request Method:获取，从而找到对应方法。使用反射查找，来执行对应方法。
1.由Request URL请求去获取路径，与urls进行匹配，找到对应的类 2.由请求体得到：Request Method：GET 3.获得类中方法 方法名 = getattr(对象，"GET") 方法名() #执行对应函数
源码查看：
@classonlymethod def as_view(cls, **initkwargs): """ Main entry point for a request-response process.请求-响应的主入口点，在url解析时调用 """ for key in initkwargs: #cls.http_method_names： #[u'get', u'post', u'put', u'patch', u'delete', u'head', u'options', u'trace'] if key in cls.http_method_names: raise TypeError("You tried to pass in the %s method name as a " "keyword argument to %s(). Don't do that." % (key, cls.__name__)) if not hasattr(cls, key): raise TypeError("%s() received an invalid keyword %r. as_view " "only accepts arguments that are already " "attributes of the class." % (cls.__name__, key)) #print(cls) #<class 'app1.views.CBV'> def view(request, *args, **kwargs): self = cls(**initkwargs) #实例化CBV对象 if hasattr(self, 'get') and not hasattr(self, 'head'): self.head = self.get self.request = request #print(request) <WSGIRequest: GET '/cbv'> #print(request.method) GET self.args = args self.kwargs = kwargs return self.dispatch(request, *args, **kwargs)#调用dispatch方法，将<WSGIRequest: GET '/cbv'>传入 view.view_class = cls view.view_initkwargs = initkwargs # take name and docstring from class update_wrapper(view, cls, updated=()) # and possible attributes set by decorators # like csrf_exempt from dispatch update_wrapper(view, cls.dispatch, assigned=()) return view def dispatch(self, request, *args, **kwargs): # Try to dispatch to the right method; if a method doesn't exist, # defer to the error handler. Also defer to the error handler if the # request method isn't on the approved list. if request.method.lower() in self.http_method_names: handler = getattr(self, request.method.lower(), self.http_method_not_allowed) #去调用对应的函数 else: handler = self.http_method_not_allowed return handler(request, *args, **kwargs)
推荐：介绍——基于类的视图（class-based view）
3.业务处理
-----根据个人需求自定义
-----对于框架：基本操作是操作数据库
---pymysql （原生）
---SQLAlchemy
---Django中orm
-----响应内容：返回给用户的结果：响应头和响应体
我们写的HTTPResponse是写在响应体中
响应头的定制：
def post(self,request): ret = HttpResponse("<h1>post</h1>")
#下面为设置请求头 ret['h1'] ='v1' ret.set_cookie('c1','v1') ret.set_cookie('c2','v2') ''' 响应头：h1=v1 cookies:c1=v1;c2=v2 响应体：<h1>post</h1> 请求头信息： Content-Length:13 Content-Type:text/html; charset=utf-8 Date:Wed, 28 Mar 2018 13:54:53 GMT h1:v1 Server:WSGIServer/0.1 Python/2.7.10 Set-Cookie:c2=v2; Path=/ Set-Cookie:c1=v1; Path=/ X-Frame-Options:SAMEORIGIN ''' return ret
