Django时区详解

# settings.py
TIME_ZONE = 'Asia/Shanghai'

# python manage.py shell
>>> from datetime import datetime
>>> datetime.now()
datetime.datetime(2016, 12, 7, 12, 41, 22, 729326)
>>> from django.utils import timezone
>>> timezone.now()
datetime.datetime(2016, 12, 7, 4, 41, 36, 685921, tzinfo=<UTC>)

>>> import datetime
>>> naive = datetime.datetime.now()
>>> naive.tzinfo
>>>

>>> import datetime
>>> import pytz
>>> aware = datetime.datetime.now(pytz.utc)
>>> aware
datetime.datetime(2016, 12, 7, 8, 32, 7, 864077, tzinfo=<UTC>)
>>> aware.tzinfo
<UTC>

@classmethod
 def now(cls, tz=None):
  "Construct a datetime from time.time() and optional time zone info."
  t = _time.time()
  return cls.fromtimestamp(t, tz)

 @classmethod
 def _fromtimestamp(cls, t, utc, tz):
  """Construct a datetime from a POSIX timestamp (like time.time()).

  A timezone info object may be passed in as well.
  """
  frac, t = _math.modf(t)
  us = round(frac * 1e6)
  if us >= 1000000:
   t += 1
   us -= 1000000
  elif us < 0:
   t -= 1
   us += 1000000

  converter = _time.gmtime if utc else _time.localtime
  y, m, d, hh, mm, ss, weekday, jday, dst = converter(t)
  ss = min(ss, 59) # clamp out leap seconds if the platform has them
  return cls(y, m, d, hh, mm, ss, us, tz)

 @classmethod
 def fromtimestamp(cls, t, tz=None):
  """Construct a datetime from a POSIX timestamp (like time.time()).

  A timezone info object may be passed in as well.
  """
  _check_tzinfo_arg(tz)

  result = cls._fromtimestamp(t, tz is not None, tz)
  if tz is not None:
   result = tz.fromutc(result)
  return result

def localtime(seconds=None): # real signature unknown; restored from __doc__
 """
 localtime([seconds]) -> (tm_year,tm_mon,tm_mday,tm_hour,tm_min,
        tm_sec,tm_wday,tm_yday,tm_isdst)

 Convert seconds since the Epoch to a time tuple expressing local time.
 When 'seconds' is not passed in, convert the current time instead.
 """
 pass

>>> from datetime import datetime
>>> from time import time, tzset
>>> china = datetime.fromtimestamp(time())
>>> import os
>>> os.environ['TZ'] = 'UTC'
>>> tzset()
>>> utc = datetime.fromtimestamp(time())
>>> china
datetime.datetime(2016, 12, 7, 16, 3, 34, 453664)
>>> utc
datetime.datetime(2016, 12, 7, 8, 4, 30, 108349)

>>> from time import time, localtime, tzset
>>> import os
>>> china = localtime()
>>> china
time.struct_time(tm_year=2016, tm_mon=12, tm_mday=7, tm_hour=16, tm_min=7, tm_sec=5, tm_wday=2, tm_yday=342, tm_isdst=0)
>>> os.environ['TZ'] = 'UTC'
>>> tzset()
>>> utc = localtime()
>>> utc
time.struct_time(tm_year=2016, tm_mon=12, tm_mday=7, tm_hour=8, tm_min=7, tm_sec=34, tm_wday=2, tm_yday=342, tm_isdst=0)
 

from django.conf import settings

class Settings(BaseSettings):
 def __init__(self, settings_module):
  # update this dict from global settings (but only for ALL_CAPS settings)
  for setting in dir(global_settings):
   if setting.isupper():
    setattr(self, setting, getattr(global_settings, setting))

  # store the settings module in case someone later cares
  self.SETTINGS_MODULE = settings_module

  mod = importlib.import_module(self.SETTINGS_MODULE)

  tuple_settings = (
   "INSTALLED_APPS",
   "TEMPLATE_DIRS",
   "LOCALE_PATHS",
  )
  self._explicit_settings = set()
  for setting in dir(mod):
   if setting.isupper():
    setting_value = getattr(mod, setting)

    if (setting in tuple_settings and
      not isinstance(setting_value, (list, tuple))):
     raise ImproperlyConfigured("The %s setting must be a list or a tuple. " % setting)
    setattr(self, setting, setting_value)
    self._explicit_settings.add(setting)

  if not self.SECRET_KEY:
   raise ImproperlyConfigured("The SECRET_KEY setting must not be empty.")

  if hasattr(time, 'tzset') and self.TIME_ZONE:
   # When we can, attempt to validate the timezone. If we can't find
   # this file, no check happens and it's harmless.
   zoneinfo_root = '/usr/share/zoneinfo'
   if (os.path.exists(zoneinfo_root) and not
     os.path.exists(os.path.join(zoneinfo_root, *(self.TIME_ZONE.split('/'))))):
    raise ValueError("Incorrect timezone setting: %s" % self.TIME_ZONE)
   # Move the time zone info into os.environ. See ticket #2315 for why
   # we don't do this unconditionally (breaks Windows).
   os.environ['TZ'] = self.TIME_ZONE
   time.tzset()

 def is_overridden(self, setting):
  return setting in self._explicit_settings

 def __repr__(self):
  return '<%(cls)s "%(settings_module)s">' % {
   'cls': self.__class__.__name__,
   'settings_module': self.SETTINGS_MODULE,
  }

# settings.py
TIME_ZONE = 'UTC'
USE_I18N = True
USE_L10N = True
USE_TZ = True

# python3 manage.py shell
>>> import datetime
>>> datetime.datetime.now()
datetime.datetime(2016, 12, 7, 9, 19, 34, 741124)
>>> datetime.datetime.utcnow()
datetime.datetime(2016, 12, 7, 9, 19, 45, 753843)

# settings.py
TIME_ZONE = 'Asia/Shanghai'

# python3 manage.py shell
>>> import datetime
>>> datetime.datetime.now()
datetime.datetime(2016, 12, 7, 17, 22, 21, 172761)
>>> datetime.datetime.utcnow()
datetime.datetime(2016, 12, 7, 9, 22, 26, 373080)

def now():
 """
 Returns an aware or naive datetime.datetime, depending on settings.USE_TZ.
 """
 if settings.USE_TZ:
  # timeit shows that datetime.now(tz=utc) is 24% slower
  return datetime.utcnow().replace(tzinfo=utc)
 else:
  return datetime.now()
 

# models.py
class Time(models.Model):

 now = models.DateTimeField()

# MySQL Tables Schema
+-------+-------------+------+-----+---------+----------------+
| Field | Type  | Null | Key | Default | Extra   |
+-------+-------------+------+-----+---------+----------------+
| id | int(11)  | NO | PRI | NULL | auto_increment |
| now | datetime(6) | NO |  | NULL |    |
+-------+-------------+------+-----+---------+----------------+