装饰器,视图系统

1.装饰器

​ 装饰器：在不改变原函数的调用方式和函数的情况下,额外的增加功能

1.简单装饰器

import time
def timer(func):
    def inner():
        print(time.time())
        func()
@timer　　#她等于func1 = timer(func1)
def func1():
    print('这是func1')
func1()

2.函数带返回值

import time
def timer(func):
    def inner():
        print(time.time())
        ret = func()
        return ret
    return inner
@timer
def func1():
    print('这是func1')
func1()

3.原函数携带参数

import time
def download(func):
    def inner(*args,**kwargs):
        print('下载软件')
        ret = func(*args,**kwargs)
        return ret
    return inner

@download  
def yue(tools):
    print('使用{}约一约'.format(tools))
    return '成功了'

print(yue('探探'))
print(yue('陌陌'))　　

结果图:　　

4. 完整的装饰器的写法

def wrapper(func):
    def inner(*args, **kwargs):
        # 执行被装饰函数之前进行的操作
        ret = func(*args, **kwargs)
        # 执行被装饰函数之后进行的操作
        return ret
    return inner

5.改变所有的装饰器使用还是不使用

import time
flag = True#通过修改他改变所有的装饰器使用还是不使用

def timer(func):
    def inner(*args,**kwargs):
        if flag:
            print(time.time())
            ret = func(*args,**kwargs)
        else:
            ret = func(*args,**kwargs)
        return ret
    return inner

@timer
def func1():
    print('func1')
func1()

6.装饰器带参数

import time
def outer(flag):
    def timer(func):
        def inner(*args,**kwargs):
            if flag:
                print(time.time())
                ret = func(*args,**kwargs)
            else:
                ret = func(*args,**kwargs)
            return ret
        return inner
    return timer

@outer(True)
def func1():
    print('func1')
@outer(False)
def func2():
    print('func2')
func1()
func2()

7.多个装饰器装饰同一个函数　　

def wrapper1(func):
    def inner(*args, **kwargs):
        print('wrapper1 前')  # 2
        ret = func(*args, **kwargs)
        print('wrapper1 后')  # 4
        return ret
    return inner

def wrapper2(func):
    def inner(*args, **kwargs):
        print('wrapper2 前')  # 1
        ret = func(*args, **kwargs)
        print('wrapper2 后')  # 5
        return ret
    return inner

@wrapper2  # func1 = wrapper2(func1)  wrapper2.inner   func=wrapper1.inner
@wrapper1  # func1 = wrapper1(func1)  wrapper1.inner   func=func1
def func1():
    print('func1')  # 3
    return 'func1的返回值'

print(func1())  # 6

8. 装饰器修复技术

from functools import wraps
def timer(func):
    @wraps(func)
    def inner():
        print(time.time())
        ret = func()  # 原来的函数
        return ret
    return inner

2.视图系统

1. CBV和FBV

1. FBV(function based view )

2. CBV(class based view)

定义:

# 增加出版社 CBV
from django.views import View

class AddPublisher(View):
    def get(self, request):
        pass

    def post(self, request):
        pass

使用:　　

url(r'^add_publisher/', views.AddPublisher.as_view()),

CBV的流程　　

views.AddPublisher.as_view() 程序加载的时候执行  ——》 view函数rators import method_decorator

给CBV加装饰器

 引入模块

from django.utils.decorators import method_decorator

装饰器

def timer(func):
    def inner(request, *args, **kwargs):
        print(func)
        print(*args, *kwargs)

        start = time.time()
        ret = func(request, *args, **kwargs)
        end = time.time()
        print('时间：{}'.format(end - start))
        return ret

    return inner

　　

1.加载某个get/post的方法上:　　

@method_decorator(timer)
def get(self, request):

2.加在self.dispatch方法上：　　

@method_decorator(timer)
def dispatch(self, request, *args, **kwargs):

3. 加在类上:指定post和get,想要指定别的就要在加

@method_decorator(timer, name='post')
@method_decorator(timer, name='get')
class AddPublisher(View):

区别

1. 不使用method_decorator

func: <function AddPublisher.dispatch at 0x00000163735176A8>args :<app01.views.AddPublisher object at 0x00000163735F7EF0> <WSGIRequest: GET '/add_publisher/'>

2. 使用method_decorator

func:<function method_decorator.<locals>.dec.<locals>.wrapper.<locals>.bound_func at 0x0000019664B4A378>arsgs: <WSGIRequest: GET '/add_publisher/'>

自己定义: dispatch

class AddPublisher(View):
    http_method_names = ['get']#设置只能get
    @method_decorator(timer)
    def dispatch(self, request, *args, **kwargs):#执行自己的方法
        ret = super().dispatch(request, *args, **kwargs)#在去执行父类的dispatch
        return ret  #返回值接收一下

2. request

print(request.method)   # GET 请求反方式
print(request.GET)      # {}  []  get()
print(request.POST)      # {}  []  get()
print(request.FILES)    
print(request.path_info,type(request.path_info))   # 路径信息   不包含IP和端口、参数

print(request.get_host())
print(request.get_full_path()) # 路径信息 + 参数 

上传文件注意事项：

1. form表单的enctype = 'multipart/form-data'

   2. request.FILES中获取文件对象

      3. 使用文件对象的chunks()

def upload(request):
    if request.method == 'POST':
        # print(request.body)
        file = request.FILES.get('f1')
        with open(file.name, 'wb') as f:
            for chunk in file.chunks():
                f.write(chunk)
        return HttpResponse('上传成功')

    return render(request, 'upload.html')

<body>
<form action="" method="post" enctype="multipart/form-data">
    {% csrf_token %}
    文件：<input type="file"  name="f1">
    <button>上传</button>
</form>
</body>

3.JsonResponse

from django.http import JsonResponse

def json_test(request):
    data = {'name': 'alex', 'pwd': 'alexdsb'}
    
    return JsonResponse(data)  #左边原样输出　　　　　　　　添加下面这个跟jsonRes...一样
    return HttpResponse(json.dumps(data), content_type='application/json') 
　　　　　　只有上边这个是输出k