特点：

1）继承自object

2）Mixin不能单独使用，需要配合GenericAPIView使用

5个扩展类：
1）ListModelMixin：list

class ListModelMixin(object):
    def list(self, request, *args, **kwargs):
        """封装获取一组数据通用代码"""
        queryset = self.get_queryset()
        serializer = self.get_serializer(queryset, many=True)
        return Response(serializer.data)

2）CreateModelMixin：create

class CreateModelMixin(object):
    def create(self, request, *args, **kwargs):
        """封装新增数据通用代码"""
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        serializer.save()  # 调用序列化器类中的create
        return Response(serializer.data, status=status.HTTP_201_CREATED)