上面的%Y等是时间格式，所以要想理解上面要表示个什么，先来看一下Python的时间格式.
- %a - abbreviated weekday name
- %A - full weekday name
- %b - abbreviated month name
- %B - full month name
- %c - preferred date and time representation
- %C - century number (the year pided by 100, range 00 to 99)
- %d - day of the month (01 to 31)
- %D - same as %m/%d/%y
- %e - day of the month (1 to 31)
- %g - like %G, but without the century
- %G - 4-digit year corresponding to the ISO week number (see %V).
- %h - same as %b
- %H - hour, using a 24-hour clock (00 to 23)
- %I - hour, using a 12-hour clock (01 to 12)
- %j - day of the year (001 to 366)
- %m - month (01 to 12)
- %M - minute
- %n - newline character
- %p - either am or pm according to the given time value
- %r - time in a.m. and p.m. notation
- %R - time in 24 hour notation
- %S - second
- %t - tab character
- %T - current time, equal to %H:%M:%S
- %u - weekday as a number (1 to 7), Monday=1. Warning: In Sun Solaris Sunday=1
- %U - week number of the current year, starting with the first Sunday as the first day of the first week
- %V - The ISO 8601 week number of the current year (01 to 53), where week 1 is the first week that has at least 4 days in the current year, and with Monday as the first day of the week
- %W - week number of the current year, starting with the first Monday as the first day of the first week
- %w - day of the week as a decimal, Sunday=0
- %x - preferred date representation without the time
- %X - preferred time representation without the date
- %y - year without a century (range 00 to 99)
- %Y - year including the century
- %Z or %z - time zone or name or abbreviation
- %% - a literal % character
我们的例子是以 年月日-时:分:秒 的形式显示日期的。
除此之外，还要理解%(asctime)s等格式符所代表的意义，%(asctime)s表示这个位置上是字符串形式的当前时间；%(levelname)s，如果是logger.debug则它是DEBUG，如果是logger.error则它是ERROR；%(message)s，假如有logger.warning("HAHA")，则在%(message)s位置上是字符串HAHA。更详细的格式符如下：%(name)s
Logger的名字
%(levelno)s
数字形式的日志级别
%(levelname)s
文本形式的日志级别
%(pathname)s
调用日志输出函数的模块的完整路径名，可能没有
%(filename)s
调用日志输出函数的模块的文件名
%(module)s
调用日志输出函数的模块名
%(funcName)s
调用日志输出函数的函数名
%(lineno)d
调用日志输出函数的语句所在的代码行
%(created)f
当前时间，用UNIX标准的表示时间的浮 点数表示
%(relativeCreated)d
输出日志信息时的，自Logger创建以 来的毫秒数
%(asctime)s
字符串形式的当前时间。默认格式是 “2003-07-08 16:49:45,896”。逗号后面的是毫秒
%(thread)d
线程ID。可能没有
%(threadName)s
线程名。可能没有
%(process)d
进程ID。可能没有
%(message)s
用户输出的消息