picture = request.FILES.get("picture","")
print(dir(picture))
# 文件对象的属性如下
['DEFAULT_CHUNK_SIZE', '__bool__', '__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__enter__', '__eq__', '__exit__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', '_get_name', '_get_size', '_get_size_from_underlying_file', '_name', '_set_name', '_set_size', '_size', 'charset', 'chunks', 'close', 'closed', 'content_type', 'content_type_extra', 'encoding', 'field_name', 'file', 'fileno', 'flush', 'isatty', 'multiple_chunks', 'name', 'newlines', 'open', 'read', 'readable', 'readinto', 'readline', 'readlines', 'seek', 'seekable', 'size', 'tell', 'truncate', 'writable', 'write', 'writelines']
