一层一层的封装，又能到底层，就会有全局感啦。。。

from rest_framework import statusfrom rest_framework.response import Responsefrom snippets.models import Snippetfrom snippets.serializers import SnippetSerializerfrom django.http import Http404from rest_framework.views import APIViewfrom rest_framework import mixinsfrom rest_framework import genericsclass SnippetListOld(APIView):    def get(self, request, format=None):        snippets = Snippet.objects.all()        serializer = SnippetSerializer(snippets, many=True)        return Response(serializer.data)    def post(self, request, format=None):        serializer = SnippetSerializer(data=request.data)        if serializer.is_valid():            serializer.save()            return Response(serializer.data, status=status.HTTP_201_CREATED)        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)class SnippetDailOld(APIView):    def get_object(self, pk):        try:            return Snippet.object.get(pk=pk)        except Snippet.DoesNotExist:            raise Http404    def get(self, request, pk, format=None):        snippet = self.get_object(pk)        serializer = SnippetSerializer(snippet)        return Response(serializer.data)    def put(self, request, pk, format=None):        snippet = self.get_object(pk)        serializer = SnippetSerializer(snippet, data=request.data)        if serializer.is_valid():            serializer.save()            return Response(serializer.data)        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)    def delete(self, request, pk, format=None):        snippet = self.get_object(pk)        snippet.delete()        return Response(status=status.HTTP_204_NO_CONTENT)class SnippetListOld2(mixins.ListModelMixin,                  mixins.CreateModelMixin,                  generics.GenericAPIView):    queryset = Snippet.objects.all()    serializer_class = SnippetSerializer    def get(self, request, *args, **kwargs):        return self.list(request, *args, **kwargs)    def post(self, request, *args, **kwargs):        return self.create(request, *args, **kwargs)class SnippetDetailOld2(mixins.RetrieveModelMixin,                    mixins.UpdateModelMixin,                    mixins.DestroyModelMixin,                    generics.GenericAPIView):    queryset = Snippet.objects.all()    serializer_class = SnippetSerializer    def get(self, request, *args, **kwargs):        return self.retrieve(request, *args, **kwargs)    def put(self, request, *args, **kwargs):        return self.update(request, *args, **kwargs)    def delete(self, request, *args, **kwargs):        return self.destroy(request, *args, **kwargs)class SnippetList(generics.ListCreateAPIView):    queryset = Snippet.objects.all()    serializer_class = SnippetSerializerclass SnippetDetail(generics.RetrieveUpdateDestroyAPIView):    queryset = Snippet.objects.all()    serializer_class = SnippetSerializer