Django文件存储 自己定制存储系统解析

要自己写一个存储系统，可以依照以下步骤：

1.写一个继承自django.core.files.storage.Storage的子类。

from django.core.files.storage import Storage
class MyStorage(Storage):
 ...

2.Django必须可以在无任何参数的情况下实例化MyStorage，所以任何环境设置必须来自django.conf.settings。

from django.conf import settings
from django.core.files.storage import Storage

class MyStorage(Storage):
 def __init__(self, option=None):
   if not option:
     option = settings.CUSTOM_STORAGE_OPTIONS
   ...

3.根据Storage的open和save方法源码:

def open(self, name, mode='rb'):
 """
 Retrieves the specified file from storage.
 """
 return self._open(name, mode)

def save(self, name, content, max_length=None):
 """
 Saves new content to the file specified by name. The content should be
 a proper File object or any python file-like object, ready to be read
 from the beginning.
 """
 # Get the proper name for the file, as it will actually be saved.
 if name is None:
   name = content.name

if not hasattr(content, 'chunks'):
   content = File(content, name)

name = self.get_available_name(name, max_length=max_length)
 return self._save(name, content)

MyStorage需要实现_open和_save方法。

如果写的是个本地存储系统，还要重写path方法。

4.使用django.utils.deconstruct.deconstructible装饰器，以便在migration可以序列化。

还有，Storage.delete()、Storage.exists()、Storage.listdir()、Storage.size()、Storage.url()方法都会报NotImplementedError，也需要重写。

Django Qiniu Storage

七牛云有自己的django storage系统，可以看下是怎么运作的，地址 https://github.com/glasslion/django-qiniu-storage 。

先在环境变量或者settings中配置QINIU_ACCESS_KEY、QINIU_SECRET_KEY、QINIU_BUCKET_NAME、QINIU_BUCKET_DOMAIN、QINIU_SECURE_URL。

使用七牛云托管用户上传的文件，在 settings.py 里设置DEFAULT_FILE_STORAGE：

DEFAULT_FILE_STORAGE = 'qiniustorage.backends.QiniuStorage'

使用七牛托管动态生成的文件以及站点自身的静态文件，设置：

STATICFILES_STORAGE = 'qiniustorage.backends.QiniuStaticStorage'

运行python manage.py collectstatic，静态文件就会被统一上传到七牛。

QiniuStorage代码如下：

@deconstructible
class QiniuStorage(Storage):
 """
 Qiniu Storage Service
 """
 location = ""

def __init__(
     self,
     access_key=QINIU_ACCESS_KEY,
     secret_key=QINIU_SECRET_KEY,
     bucket_name=QINIU_BUCKET_NAME,
     bucket_domain=QINIU_BUCKET_DOMAIN,
     secure_url=QINIU_SECURE_URL):

self.auth = Auth(access_key, secret_key)
   self.bucket_name = bucket_name
   self.bucket_domain = bucket_domain
   self.bucket_manager = BucketManager(self.auth)
   self.secure_url = secure_url

def _clean_name(self, name):
   """
   Cleans the name so that Windows style paths work
   """
   # Normalize Windows style paths
   clean_name = posixpath.normpath(name).replace('\\', '/')

# os.path.normpath() can strip trailing slashes so we implement
   # a workaround here.
   if name.endswith('/') and not clean_name.endswith('/'):
     # Add a trailing slash as it was stripped.
     return clean_name + '/'
   else:
     return clean_name

def _normalize_name(self, name):
   """
   Normalizes the name so that paths like /path/to/ignored/../foo.txt
   work. We check to make sure that the path pointed to is not outside
   the directory specified by the LOCATION setting.
   """

base_path = force_text(self.location)
   base_path = base_path.rstrip('/')

final_path = urljoin(base_path.rstrip('/') + "/", name)

base_path_len = len(base_path)
   if (not final_path.startswith(base_path) or
       final_path[base_path_len:base_path_len + 1] not in ('', '/')):
     raise SuspiciousOperation("Attempted access to '％s' denied." ％
                  name)
   return final_path.lstrip('/')

def _open(self, name, mode='rb'):
   return QiniuFile(name, self, mode)

def _save(self, name, content):
   cleaned_name = self._clean_name(name)
   name = self._normalize_name(cleaned_name)

if hasattr(content, 'chunks'):
     content_str = b''.join(chunk for chunk in content.chunks())
   else:
     content_str = content.read()

self._put_file(name, content_str)
   return cleaned_name

def _put_file(self, name, content):
   token = self.auth.upload_token(self.bucket_name)
   ret, info = put_data(token, name, content)
   if ret is None or ret['key'] != name:
     raise QiniuError(info)

def _read(self, name):
   return requests.get(self.url(name)).content

def delete(self, name):
   name = self._normalize_name(self._clean_name(name))
   if six.PY2:
     name = name.encode('utf-8')
   ret, info = self.bucket_manager.delete(self.bucket_name, name)

if ret is None or info.status_code == 612:
     raise QiniuError(info)

def _file_stat(self, name, silent=False):
   name = self._normalize_name(self._clean_name(name))
   if six.PY2:
     name = name.encode('utf-8')
   ret, info = self.bucket_manager.stat(self.bucket_name, name)
   if ret is None and not silent:
     raise QiniuError(info)
   return ret

def exists(self, name):
   stats = self._file_stat(name, silent=True)
   return True if stats else False

def size(self, name):
   stats = self._file_stat(name)
   return stats['fsize']

def modified_time(self, name):
   stats = self._file_stat(name)
   time_stamp = float(stats['putTime']) / 10000000
   return datetime.datetime.fromtimestamp(time_stamp)

def listdir(self, name):
   name = self._normalize_name(self._clean_name(name))
   if name and not name.endswith('/'):
     name += '/'

dirlist = bucket_lister(self.bucket_manager, self.bucket_name,
               prefix=name)
   files = []
   dirs = set()
   base_parts = name.split("/")[:-1]
   for item in dirlist:
     parts = item['key'].split("/")
     parts = parts[len(base_parts):]
     if len(parts) == 1:
       # File
       files.append(parts[0])
     elif len(parts) > 1:
       # Directory
       dirs.add(parts[0])
   return list(dirs), files

def url(self, name):
   name = self._normalize_name(self._clean_name(name))
   name = filepath_to_uri(name)
   protocol = u'https://' if self.secure_url else u'http://'
   return urljoin(protocol + self.bucket_domain, name)

配置是从环境变量或者settings.py中获得的：

def get_qiniu_config(name, default=None):
 """
 Get configuration variable from environment variable
 or django setting.py
 """
 config = os.environ.get(name, getattr(settings, name, default))
 if config is not None:
   if isinstance(config, six.string_types):
     return config.strip()
   else:
     return config
 else:
   raise ImproperlyConfigured(
     "Can't find config for '％s' either in environment"
     "variable or in setting.py" ％ name)
QINIU_ACCESS_KEY = get_qiniu_config('QINIU_ACCESS_KEY')
QINIU_SECRET_KEY = get_qiniu_config('QINIU_SECRET_KEY')
QINIU_BUCKET_NAME = get_qiniu_config('QINIU_BUCKET_NAME')
QINIU_BUCKET_DOMAIN = get_qiniu_config('QINIU_BUCKET_DOMAIN', '').rstrip('/')
QINIU_SECURE_URL = get_qiniu_config('QINIU_SECURE_URL', 'False')

重写了_open和_save方法：

def _open(self, name, mode='rb'):
 return QiniuFile(name, self, mode)
def _save(self, name, content):
 cleaned_name = self._clean_name(name)
 name = self._normalize_name(cleaned_name)
 if hasattr(content, 'chunks'):
   content_str = b''.join(chunk for chunk in content.chunks())
 else:
   content_str = content.read()
 self._put_file(name, content_str)
 return cleaned_name

使用的put_data方法上传文件，相关代码如下：

def put_data(
   up_token, key, data, params=None, mime_type='application/octet-stream', check_crc=False, progress_handler=None,
   fname=None):
 """上传二进制流到七牛
 Args:
   up_token:     上传凭证
   key:       上传文件名
   data:       上传二进制流
   params:      自定义变量，规格参考 http://developer.qiniu.com/docs/v6/api/overview/up/response/vars.html#xvar
   mime_type:    上传数据的mimeType
   check_crc:    是否校验crc32
   progress_handler: 上传进度

Returns:
   一个dict变量，类似 {"hash": "<Hash string>", "key": "<Key string>"}
   一个ResponseInfo对象
 """
 crc = crc32(data) if check_crc else None
 return _form_put(up_token, key, data, params, mime_type, crc, progress_handler, fname)

def _form_put(up_token, key, data, params, mime_type, crc, progress_handler=None, file_name=None):
 fields = {}
 if params:
   for k, v in params.items():
     fields[k] = str(v)
 if crc:
   fields['crc32'] = crc
 if key is not None:
   fields['key'] = key
 fields['token'] = up_token
 url = config.get_default('default_zone').get_up_host_by_token(up_token) + '/'
 # name = key if key else file_name

fname = file_name
 if not fname or not fname.strip():
   fname = 'file_name'

r, info = http._post_file(url, data=fields, files={'file': (fname, data, mime_type)})
 if r is None and info.need_retry():
   if info.connect_failed:
     url = config.get_default('default_zone').get_up_host_backup_by_token(up_token) + '/'
   if hasattr(data, 'read') is False:
     pass
   elif hasattr(data, 'seek') and (not hasattr(data, 'seekable') or data.seekable()):
     data.seek(0)
   else:
     return r, info
   r, info = http._post_file(url, data=fields, files={'file': (fname, data, mime_type)})

return r, info
def _post_file(url, data, files):
 return _post(url, data, files, None)
def _post(url, data, files, auth, headers=None):
 if _session is None:
   _init()
 try:
   post_headers = _headers.copy()
   if headers is not None:
     for k, v in headers.items():
       post_headers.update({k: v})
   r = _session.post(
     url, data=data, files=files, auth=auth, headers=post_headers,
     timeout=config.get_default('connection_timeout'))
 except Exception as e:
   return None, ResponseInfo(None, e)
 return __return_wrapper(r)
def _init():
 session = requests.Session()
 adapter = requests.adapters.HTTPAdapter(
   pool_connections=config.get_default('connection_pool'), pool_maxsize=config.get_default('connection_pool'),
   max_retries=config.get_default('connection_retries'))
 session.mount('http://', adapter)
 global _session
 _session = session

最终使用的是requests库上传文件的，统一适配了链接池个数、链接重试次数。

来源：https://www.cnblogs.com/linxiyue/p/7456004.html