Python模块学习——logging

logging模块是在2.3新引进的功能，下面是一些常用的类和模块级函数

模块级函数

logging.getLogger([name]):返回一个logger对象，如果没有指定名字将返回root logger

logging.debug()、logging.info()、logging.warning()、logging.error()、logging.critical()：设定root logger的日志级别

logging.basicConfig():用默认Formatter为日志系统建立一个StreamHandler，设置基础配置并加到root logger中

 

import logging

import sys



LEVELS = {'debug': logging.DEBUG,

          'info': logging.INFO,

          'warning': logging.WARNING,

          'error': logging.ERROR,

          'critical': logging.CRITICAL}



if len(sys.argv) > 1:

    level_name = sys.argv[1]

    level = LEVELS.get(level_name, logging.NOTSET)

    logging.basicConfig(level=level)



logging.debug('This is a debug message')

logging.info('This is an info message')

logging.warning('This is a warning message')

logging.error('This is an error message')

logging.critical('This is a critical error message')

 

$ python logging_level_example.py debug

DEBUG:root:This is a debug message

INFO:root:This is an info message

WARNING:root:This is a warning message

ERROR:root:This is an error message

CRITICAL:root:This is a critical error message



$ python logging_level_example.py info

INFO:root:This is an info message

WARNING:root:This is a warning message

ERROR:root:This is an error message

CRITICAL:root:This is a critical error message

 

 

Loggers

Logger.setLevel(lel):指定最低的日志级别，低于lel的级别将被忽略。debug是最低的内置级别，critical为最高

Logger.addFilter(filt)、Logger.removeFilter(filt):添加或删除指定的filter

Logger.addHandler(hdlr)、Logger.removeHandler(hdlr)：增加或删除指定的handler

Logger.debug()、Logger.info()、Logger.warning()、Logger.error()、Logger.critical()：可以设置的日志级别

 

import logging



# create logger

logger = logging.getLogger("simple_example")

logger.setLevel(logging.DEBUG)



# create console handler and set level to debug

ch = logging.StreamHandler()

ch.setLevel(logging.DEBUG)



# create formatter

formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")



# add formatter to ch

ch.setFormatter(formatter)



# add ch to logger

logger.addHandler(ch)



# "application" code

logger.debug("debug message")

logger.info("info message")

logger.warn("warn message")

logger.error("error message")

logger.critical("critical message")

$ python simple_logging_module.py

2005-03-19 15:10:26,618 - simple_example - DEBUG - debug message

2005-03-19 15:10:26,620 - simple_example - INFO - info message

2005-03-19 15:10:26,695 - simple_example - WARNING - warn message

2005-03-19 15:10:26,697 - simple_example - ERROR - error message

2005-03-19 15:10:26,773 - simple_example - CRITICAL - critical message

 

Handlers

handler对象负责发送相关的信息到指定目的地。可以通过addHandler()方法添加多个多handler

Handler.setLevel(lel):指定被处理的信息级别，低于lel级别的信息将被忽略

Handler.setFormatter()：给这个handler选择一个格式

Handler.addFilter(filt)、Handler.removeFilter(filt)：新增或删除一个filter对象

Formatters

Formatter对象设置日志信息最后的规则、结构和内容，默认的时间格式为%Y-%m-%d %H:%M:%S，下面是Formatter常用的一些信息

%(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

最后来个例子

 

import logging



# set up logging to file - see previous section for more details

logging.basicConfig(level=logging.DEBUG,

                    format='%(asctime)s %(name)-12s %(levelname)-8s %(message)s',

                    datefmt='%m-%d %H:%M',

                    filename='/temp/myapp.log',

                    filemode='w')

# define a Handler which writes INFO messages or higher to the sys.stderr

console = logging.StreamHandler()

console.setLevel(logging.INFO)

# set a format which is simpler for console use

formatter = logging.Formatter('%(name)-12s: %(levelname)-8s %(message)s')

# tell the handler to use this format

console.setFormatter(formatter)

# add the handler to the root logger

logging.getLogger('').addHandler(console)



# Now, we can log to the root logger, or any other logger. First the root...

logging.info('Jackdaws love my big sphinx of quartz.')



# Now, define a couple of other loggers which might represent areas in your

# application:



logger1 = logging.getLogger('myapp.area1')

logger2 = logging.getLogger('myapp.area2')



logger1.debug('Quick zephyrs blow, vexing daft Jim.')

logger1.info('How quickly daft jumping zebras vex.')

logger2.warning('Jail zesty vixen who grabbed pay from quack.')

logger2.error('The five boxing wizards jump quickly.')

运行后，在终端看到的结果

 

root        : INFO     Jackdaws love my big sphinx of quartz.

myapp.area1 : INFO     How quickly daft jumping zebras vex.

myapp.area2 : WARNING  Jail zesty vixen who grabbed pay from quack.

myapp.area2 : ERROR    The five boxing wizards jump quickly.

 

在日志文件中的结果

 

10-22 22:19 root         INFO     Jackdaws love my big sphinx of quartz.

10-22 22:19 myapp.area1  DEBUG    Quick zephyrs blow, vexing daft Jim.

10-22 22:19 myapp.area1  INFO     How quickly daft jumping zebras vex.

10-22 22:19 myapp.area2  WARNING  Jail zesty vixen who grabbed pay from quack.

10-22 22:19 myapp.area2  ERROR    The five boxing wizards jump quickly.

发现DEBUG信息只有在文件中出现，这是因为StreamHandler中setLevel是INFO，可以看出Logger.setLevel()和handler.setLevel()的区别

详细信息请参阅 http://docs.python.org/library/logging.html