datetime的时区转换

1.将时区信息添加到datetime日期时间对象

from datetime import datetime
from pytz import timezone

date_str = "2009-05-05 22:28:15"
datetime_obj = datetime.strptime(date_str, "%Y-%m-%d %H:%M:%S")
datetime_obj_utc = datetime_obj.replace(tzinfo=timezone('UTC'))
print(datetime_obj_utc.strftime("%Y-%m-%d %H:%M:%S %Z%z"))

运行结果：
2009-05-05 22:28:15 UTC+0000

2.将非UTC时区信息添加到datetime日期时间对象

from datetime import datetime
from pytz import timezone

date_str = "2014-05-28 22:28:15"
datetime_obj_naive = datetime.strptime(date_str, "%Y-%m-%d %H:%M:%S")

# 错误的方式❌!
datetime_obj_pacific = datetime_obj_naive.replace(tzinfo=timezone('US/Pacific'))
print(datetime_obj_pacific.strftime("%Y-%m-%d %H:%M:%S %Z%z"))

# 正确的方式✅!
datetime_obj_pacific = timezone('US/Pacific').localize(datetime_obj_naive)
print(datetime_obj_pacific.strftime("%Y-%m-%d %H:%M:%S %Z%z"))

运行结果：
2014-05-28 22:28:15 PST-0800
2014-05-28 22:28:15 PDT-0700

3.时区转换

from datetime import datetime
from pytz import timezone

fmt = "%Y-%m-%d %H:%M:%S %Z%z"

# Current time in UTC
now_utc = datetime.now(timezone('UTC'))
print(now_utc.strftime(fmt))

# Convert to US/Pacific time zone
now_pacific = now_utc.astimezone(timezone('US/Pacific'))
print(now_pacific.strftime(fmt))

# Convert to Europe/Berlin time zone
now_berlin = now_pacific.astimezone(timezone('Europe/Berlin'))
print(now_berlin.strftime(fmt))

运行结果：
2009-05-06 03:09:49 UTC+0000
2009-05-05 20:09:49 PDT-0700
2009-05-06 05:09:49 CEST+0200

4.查看所有时区

from pytz import all_timezones

print len(all_timezones)
for zone in all_timezones:
    if 'US' in zone:
        print(zone)

运行结果：
US/Alaska
US/Aleutian
US/Arizona
US/Central
US/East-Indiana
US/Eastern
US/Hawaii
US/Indiana-Starke
US/Michigan
US/Mountain
US/Pacific
US/Pacific-New
US/Samoa