class A:
  def get_name(self):
    return self.name
  def return_name(self):
    if hasattr(self, 'name'):
      return 'name: ' + getattr(self, 'name', None)  
  
  
class B(A):
  name = "b"
  def get_name(self):
    return self.name
  
b = B()
b.get_name() # 輸出B
b.return_name() # 輸出name: B，這里由于B類中沒有實現(xiàn)return_name方法，實例化B得到b之后，會調(diào)用父類A中的return_name方法，hasattr方法會查找類中是否有name屬性，這里雖然在類A中沒有，會向下查找B類中是否有name屬性，然后返回'name: ' + getattr(self, 'name', None) ，也就是name：b

class X(object):
  def f(self):
    print( 'x')

class A(X):
  def f(self):
    print('a')

  def extral(self):
    print('extral a')

class B(X):
  def f(self):
    print('b')

  def extral(self):
    print( 'extral b')

class C(A, B, X):
  def f(self):
    super(C, self).f()
    print('c')

print(C.mro())

c = C()
c.f()
c.extral()

class Bird:
  def fly(self):
    print('fly')

class Fish:
  def swim(self):
    print('swim')
    
class Horse:
  def run(self):
    print('run')
    
    
class Something(Bird, Fish, Horse):
  pass


s = Something()
s.fly()
s.swim()
s.run()

class BirdMixin:
  def fly(self):
    print('fly')

class FishMixin:
  def swim(self):
    print('swim')
    
class Horse:
  def run(self):
    print('run')
    
    
class Something(BirdMixin, FishMixin, Horse):
  pass

class CreateAPIView(mixins.CreateModelMixin,
          GenericAPIView):
  pass


class ListAPIView(mixins.ListModelMixin,
         GenericAPIView):
  pass


class RetrieveAPIView(mixins.RetrieveModelMixin,
           GenericAPIView):
  pass

from django.db import models


class UserInfo(models.Model):
  USER_TYPE = (
    (1,'普通用戶'),
    (2,'VIP'),
    (3,'SVIP')
  )

  user_type = models.IntegerField(choices=USER_TYPE， default=1)
  username = models.CharField(max_length=32)
  password = models.CharField(max_length=64)

class UserToken(models.Model):
  user = models.OneToOneField(UserInfo,on_delete=models.CASCADE)
  token = models.CharField(max_length=64)

python manage.py makemigrations
python manage.py migrate

from django.contrib import admin
from django.urls import path
from django.conf.urls import url

from api.views import AuthView


urlpatterns = [
  path('admin/', admin.site.urls),
  url(r'^api/v1/auth/$', AuthView.as_view())
]

from django.shortcuts import render, HttpResponse
from django.http import JsonResponse
from django.views import View

from api import models


def md5(user):
  import hashlib
  import time

  # 當(dāng)前時間，相當(dāng)于生成一個隨機的字符串
  ctime = str(time.time())

  # token加密
  m = hashlib.md5(bytes(user, encoding='utf-8'))
  m.update(bytes(ctime, encoding='utf-8'))
  return m.hexdigest()


class AuthView(View):

  def get(self, request, *args, **kwargs):
    ret = {'code': 1000, 'msg': 'success', 'name': '偷偷'}
    ret = json.dumps(ret, ensure_ascii=False)

    return HttpResponse(ret)

  def post(self, request, *args, **kwargs):
    ret = {'code': 1000, 'msg': None}
    try:
      user = request.POST.get('username')
      pwd = request.POST.get('password')
      obj = models.UserInfo.objects.filter(username=user).first()

      if not obj:
        # 如果用戶第一次登陸則創(chuàng)建用戶
        obj = models.UserInfo.objects.create(username=user, password=pwd)
        ret['code'] = 1001
        ret['msg'] = '創(chuàng)建用戶成功'

      # 為用戶創(chuàng)建token
      token = md5(user)
      # 存在就更新，不存在就創(chuàng)建
      models.UserToken.objects.update_or_create(user=obj, defaults={'token': token})
      ret['token'] = token
    except Exception as e:
      ret['code'] = 1002
      ret['msg'] = '請求異常'
    return JsonResponse(ret)

from rest_framework.views import APIView
from django.http import JsonResponse
from rest_framework.authentication import BaseAuthentication
from rest_framework import exceptions

from api import models


# 這里直接表示訂單
ORDER_DICT = {
  1:{
    'name':'apple',
    'price':15
  },
  2:{
    'name':'狗子',
    'price':100
  }
}


class FirstAuthenticate(BaseAuthentication):
  # 添加自己的認證邏輯，基類BaseAuthentication中有一個必須要重寫的接口

  def authenticate(self, request):
    pass

  def authenticate_header(self, request):
    pass


class MyAuthenticate(BaseAuthentication):
  # 添加自己的認證邏輯，基類BaseAuthentication中有兩個必須要重寫的接口

  def authenticate(self, request):
    token = request._request.GET.get('token') # 獲取token參數(shù)
    token_obj = models.UserToken.objects.filter(token=token).first() # 在數(shù)據(jù)庫UserToken查找是否有相應(yīng)的對象
    if not token_obj: # 如果沒有，則報錯
      raise exceptions.AuthenticationFailed('用戶認證失敗')
    return (token_obj.user, token_obj) # 這里需要返回兩個對象，分別是UserInfo對象和UserToken對象
 
  def authenticate_header(self, request): # 返回相應(yīng)頭信息
     pass


class OrderView(APIView):
  # 用戶想要獲取訂單，就要先通過身份認證、
  # 這里的authentication_classes 就是用戶的認證類
  authentication_classes = [FirestAuthenticate， MyAuthenticate]
  
  def get(self, request, *args, **kwargs):
    ret = {
      'code': 1024,
      'msg': '訂單獲取成功',
    }
    try:
      ret['data'] = ORDER_DICT
    except Exception as e:
      pass
    return JsonResponse(ret)

REST_FRAMEWORK = {
  'DEFAULT_AUTHENTICATION_CLASSES': ['api.utils.authenticate.FirstAuthenticate', 'api.utils.authenticate.MyAuthenticate'],
}

class OrderView(APIView):
  # 這里沒有重寫authentication_classes屬性，則使用全局配置的authentication_classes，即在setting.py中的authentication_classes。
  def get(self, request, *args, **kwargs):
     pass

class CartView(APIView):
   authentication_classes = [authenticate.FirstAuthenticate,] # authentication_classes中只包含F(xiàn)irstAuthenticate，則只通過他的認證
  def get(self, request, *args, **kwargs):
     pass

class UserInfoView(APIView):
  authentication_classes = [] # authentication_classes為空，則不會進行認證
  def get(self, request, *args, **kwargs):
     pass

def _authenticate(self):
    """
    Attempt to authenticate the request using each authentication instance
    in turn.
    """
    for authenticator in self.authenticators: # 找到 authentication_classes，并循環(huán)每一個認證類
      try:
        user_auth_tuple = authenticator.authenticate(self) # 調(diào)用認證類的authenticate方法，也就是上面我們實現(xiàn)的方法，并將返回值賦值給user_auth_tuple
      except exceptions.APIException:
        self._not_authenticated() # 如果出錯調(diào)用_not_authenticated，方法，下面會說到
        raise

      if user_auth_tuple is not None: # 如果authenticate方法的返回值不為空
        self._authenticator = authenticator
        self.user, self.auth = user_auth_tuple # 這也就是為什么認證類的authenticate方法會返回兩個對象的原因
        return

    self._not_authenticated() # 如果沒有通過認證，則調(diào)用_not_authenticated方法

  def _not_authenticated(self):
    """
    Set authenticator, user & authtoken representing an unauthenticated request.

    Defaults are None, AnonymousUser & None.
    """
    self._authenticator = None

    if api_settings.UNAUTHENTICATED_USER:
      self.user = api_settings.UNAUTHENTICATED_USER()
    else:
      self.user = None

    if api_settings.UNAUTHENTICATED_TOKEN:
      self.auth = api_settings.UNAUTHENTICATED_TOKEN()
    else:
      self.auth = None

REST_FRAMEWORK = {
  'DEFAULT_AUTHENTICATION_CLASSES': ['api.utils.authenticate.FirstAuthenticate', 'api.utils.authenticate.MyAuthenticate'],
  "UNAUTHENTICATED_USER": None, # 匿名，request.user = None
  "UNAUTHENTICATED_TOKEN": None,# 匿名，request.auth = None
}