logging 文件日志

1. 例子

import logging
logging.basicConfig(filename='log.txt',  #文件名
                    level=logging.DEBUG, #级别
                    format=u'时间:%(asctime)s\n级别:%(levelname)s\n消息:%(message)s\n',  #日志格式
                    datefmt='%Y-%m-%d %H:%M:%S') # 时间格式
logging.debug(u'第一条记录') 
logging.info(u'第二条记录') 

2. 级别

日志所记录的消息可以划分为不同的级别，一般用以下几种预定义的级别。

每种级别有对应的值，可以用来比较级别的高低。

级别	值
CRITICAL	50
ERROR	40
WARNING	30
INFO	20
DEBUG	10
NOTSET	0

每个级别都有对应的方法，用小写字母，比如 logging.debug() , logging.info()，分别用来记录 DEBUG 级别和 INFO 级别的消息。

logging.basicConfig 中配置的级别可以用来过滤消息，比配置级别低的消息将被忽略，不会写入文件。

比如，如果一开始配置的是 level=logging.INFO ，那么调用 logging.debug() 处理的消息将被忽略，不会记录到文件。只有用 info() 或者 warning() 以及更高级别才会被记录。

3. 日志格式

格式化字符串支持如下参数:

参数	解释
%(asctime)s	Human-readable time when the LogRecord was created. By default this is of the form '2003-07-08 16:49:45,896'.
%(created)f	Time when the LogRecord was created (as returned by time.time()).
%(filename)s	Filename portion of pathname.
%(funcName)s	Name of function containing the logging call.
%(levelname)s	Text logging level for the message ('DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL').
%(levelno)s	Numeric logging level for the message (DEBUG, INFO, WARNING, ERROR, CRITICAL).
%(lineno)d	Source line number where the logging call was issued (if available).
%(module)s	Module (name portion of filename).
%(msecs)d	Millisecond portion of the time when the LogRecord was created.
%(message)s	The logged message.
%(name)s	Name of the logger used to log the call.
%(pathname)s	Full pathname of the source file where the logging call was issued (if available).
%(process)d	Process ID (if available).
%(processName)s	Process name (if available).
%(relativeCreated)d	Time in milliseconds when the LogRecord was created, relative to the time the logging module was loaded.
%(thread)d	Thread ID (if available).
%(threadName)s	Thread name (if available).

3. 时间格式

时间格式化字符串与time.strftime()使用相同的参数

参数	解释
%a	Locale's abbreviated weekday name.
%A	Locale's full weekday name.
%b	Locale's abbreviated month name.
%B	Locale's full month name.
%c	Locale's appropriate date and time representation.
%d	Day of the month as a decimal number [01,31].
%H	Hour (24-hour clock) as a decimal number [00,23].
%I	Hour (12-hour clock) as a decimal number [01,12].
%j	Day of the year as a decimal number [001,366].
%m	Month as a decimal number [01,12].
%M	Minute as a decimal number [00,59].
%p	Locale's equivalent of either AM or PM.
%S	Second as a decimal number [00,61].
%U	Week number of the year (Sunday as the first day of the week) as a decimal number [00,53].
%w	Weekday as a decimal number [0(Sunday),6].
%W	Week number of the year (Monday as the first day of the week) as a decimal number [00,53].
%x	Locale's appropriate date representation.
%X	Locale's appropriate time representation.
%y	Year without century as a decimal number [00,99].
%Y	Year with century as a decimal number.
%Z	Time zone name (no characters if no time zone exists).
%%	A literal '%' character.

4. 另一种写法

麻烦一点，但是可以定制多个logger

import logging

logger = logging.getLogger(u'mylogger')  
handler = logging.FileHandler(u'log1.txt')  
formatter = logging.Formatter(u'时间:%(asctime)s\n级别:%(levelname)s\n消息:%(message)s\n')  
handler.setFormatter(formatter)  
logger.addHandler(handler)  
logger.setLevel(logging.DEBUG)
logger.debug(u'第一条记录')
logger.info(u'第二条记录')

logger2 = logging.getLogger(u'mylogger2')  
handler2 = logging.FileHandler(u'log2.txt')  
formatter2 = logging.Formatter(u'时间:%(asctime)s\n级别:%(levelname)s\n消息:%(message)s\n')  
handler2.setFormatter(formatter2)  
logger2.addHandler(handler2)  
logger2.setLevel(logging.DEBUG)
logger2.debug(u'第一条记录')
logger2.info(u'第二条记录')