在OSS API文档中，使用DATE表示时间的字段。该字段必须为HTTP1.1中支持的三种GMT格式时间，您仅需提供三种格式中的任意一种即可。
说明 HTTP1.1协议详情请参见
HTTP1.1协议说明。
DATE字段具体的格式可参考如下格式：
HTTP-date = rfc1123-date | rfc850-date | asctime_date其中，
rfc1123-date = wkday "," SP date1 SP time SP "GMT" rfc850-date = weekday "," SP date2 SP time SP "GMT" asctime-date = wkday SP date3 SP time SP 4DIGIT date1 = 2DIGIT SP month SP 4DIGIT ; day month year (e.g., 02 Jun 1982) date2 = 2DIGIT "-" month "-" 2DIGIT ; day-month-year (e.g., 02-Jun-82) date3 = month SP ( 2DIGIT | ( SP 1DIGIT )) ; month day (e.g., Jun 2) <----- 注意： 日期没有前导零，需空格占位。 SP表示空格，DIGIT表示数值，2DIGIT表示两位的数值。 wkday = "Mon" | "Tue" | "Wed" | "Thu" | "Fri" | "Sat" | "Sun" weekday = "Monday" | "Tuesday" | "Wednesday" | "Thursday" | "Friday" | "Saturday" | "Sunday" month = "Jan" | "Feb" | "Mar" | "Apr" | "May" | "Jun" | "Jul" | "Aug" | "Sep" | "Oct" | "Nov" | "Dec"
