python时间加减/时间格式转换

一 时间格式转字符串

# 第一种日期格式
        t1 = datetime.datetime.now()
        t1Str = t1.strftime("%Y-%m-%d %H:%M:%S")
        print(t1Str)
        # 2022-06-10 16:31:34

        # 第二种日期格式
        t2 = time.localtime()
        print(time.time())
        # 时间戳 1654850774.92928
        t2Str = time.strftime("%Y-%m-%d %H:%M:%S", t2)
        print(t2)
        # time.struct_time(tm_year=2022, tm_mon=6, tm_mday=10, tm_hour=16, tm_min=36, tm_sec=15, tm_wday=4, tm_yday=161, tm_isdst=0)
        print("year=%s,month=%s,day=%s" % (t2[0], t2[1], t2[2]))
        # year=2022,month=6,day=10
        # 2022
        print(t2Str)
        # 2022-06-10 16:31:34 strftime是转为字符串

 

二 字符串格式转时间格式

dateStr = "2022-06-10 16:16:16"
        dateTime = datetime.datetime.strptime(dateStr, "%Y-%m-%d %H:%M:%S")
        print(dateTime)
        # 2022-06-10 16:16:16 strptime是转为时间格式

 

三 时间差处理

datetime.timedelta(days=0,seconds=0,microseconds=0,milliseconds=0,minutes=0,hours=0,weeks=0)
        nowDate = datetime.datetime.now()
        # 将时间调慢2小时
        updateDate = nowDate - datetime.timedelta(hours=2)
        print(updateDate)

        delta = nowDate - updateDate
        print(delta.days)
        # 输出 0
        print(delta.seconds)
        # 输出 7200

四 实际应用举例

在当前时间的基础上减去8小时，加入时间格式转换举例
editTime = eachOne["editTime"]
out_date = (editTime - datetime.timedelta(hours=8)).strftime("%Y-%m-%d %H:%M:%S")
newDate = datetime.datetime.strptime(out_date,"%Y-%m-%d %H:%M:%S")
#更新mongo数据库
collection.update_one({"_id": eachOne["_id"]}, {"$set": {"editTime": newDate}})