python標準庫 datetime的astimezone設定時區遇到的坑及解決

# 從 datetime 中匯入 datetime 模組。
from datetime import datetime
 
 
utc_time = datetime.utcnow()    # utcnow()獲取世界標準時間。
print(f'1、UTC時間為：{utc_time}')
 
local_time = datetime.now()     # now() 獲取本地時間。
print(f'1、本地時間為：{local_time}')

timedelta([days[, seconds[, microseconds[, milliseconds[, minutes[, hours[, weeks]]]]]]]) 

from datetime import timezone, timedelta
 
beijing = timezone(timedelta(hours=8))
print(f'1、北京時區為：{beijing}')
 
Tokyo = timezone(timedelta(hours=9))
print(f'2、東京時區為：{Tokyo}')
 
New_York = timezone(timedelta(hours=-4))
print(f'3、紐約時區為：{New_York}')
 
utc = timezone.utc
print(f'4、世界標準時區為：{utc}')

utc_time = datetime.utcnow()
print(f'UTC時間為：{utc_time}')
print(f'本地時間為：{datetime.now()}')
 
time_beijing = utc_time.astimezone(beijing)
time_tokyo = utc_time.astimezone(Tokyo)
time_newyork = utc_time.astimezone(New_York)
 
print('1、更改時區為北京後的時間：', time_beijing)
print('2、更改時區為東京後的時間：', time_tokyo)
print('3、更改時區為紐約後的時間：', time_newyork)

print(utc_time.tzinfo)

utc_time = datetime.utcnow()    # 獲取當前 UTC 時間
print(f'UTC時間為：{utc_time}')
local_time = datetime.now()     # 獲取當前本地時間
print(f'本地時間為：{local_time}')
 
utc = timezone.utc                                  # 獲取 UTC 的時區物件
utc_time = datetime.utcnow().replace(tzinfo=utc)    # 強制轉換加上 UTC 時區。此處敲黑板，需要特別注意。
                                                    # replace的tzinfo引數為時區物件，所以
                                                    # 也可以這樣 replace(tzinfo=timezone(timedelta(hours=0))
print(f'1、強制更改後的UTC時間為：{utc_time}')
 
time_beijing = utc_time.astimezone(beijing)
time_newyork = utc_time.astimezone(New_York)
time_tokyo = utc_time.astimezone(Tokyo)
print('2、更改時區為北京後的時間：', time_beijing)
print('3、獲取時區資訊：', time_beijing.tzinfo)
print('4、更改時區為東京後的時間：', time_tokyo)
print('5、獲取時區資訊：', time_tokyo.tzinfo)
print('6、更改時區為紐約後的時間：', time_newyork)
print('7、獲取時區資訊：', time_newyork.tzinfo)

time_beijing.timestamp() == time_tokyo.timestamp() == time_newyork.timestamp()

pip install pytz
import pytz  
from datetime import datetime
 
u = datetime.utcnow()
u = u.replace(tzinfo=pytz.utc) #NOTE: it works only with a fixed utc offset
 
print(u)   # prints UTC time
>>> '2020-10-23 06:33:19+00:00'
print(u.astimezone(pytz.timezone("America/New_York")))     # prints another timezone
>>> '2020-10-23 02:33:19-04:00'
 
t = datetime.now(tz=pytz.timezone('Asia/Shanghai')
print(t)
>>> '2020-10-23 14:33:19+08:00'
print(t.astimezone(pytz.timezone("America/New_York")))
>>> '2020-10-23 02:33:19-04:00'
 
t = datetime.now()
print(t)
>>> '2020-10-23 14:33:19'
print(t.astimezone(pytz.timezone("America/New_York")))
>>> ValueError: astimezone() cannot be applied to a naive datetime

from datetime import datetime, timedelta, timezone
 
u = datetime.utcnow()
u = u.replace(tzinfo=timezone.utc) #NOTE: it works only with a fixed utc offset
 
print(u)   # prints UTC time
>>> '2020-10-23 06:33:19+00:00'
print(u.astimezone(timezone(timedelta(hours=-4), "America/New_York")))    # prints another timezone
>>> '2020-10-23 02:33:19-04:00'

datetime.timezone(offset, name=None)¶