Python学习之logging模块

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Python自带日志处理模块logging

默认的日志级别有DEBUG,INFO,WARNING,ERROR,CRITICAL，对应的函数是debug(),info(),warning(),error()和critical()

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In [490]: import logging In [491]: LOG_FILENAME='/tmp/example.log' In [492]: logging.basicConfig(filename=LOG_FILENAME,level=logging.DEBUG) In [493]: logging.debug('This message should go to the log file')

查看/tmp/example.log的内容

1 2	$ cat /tmp/example.log DEBUG:root:This message should go to the log file

不断执行

1	logging.debug('This message should go to the log file')

/tmp/example.log会不断地刷新


日志轮转

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In [639]: import glob In [640]: import logging In [641]: import logging.handlers In [642]: LOG_FILENAME='/tmp/logging_rotatingfile_example.out' In [643]: my_logger=logging.getLogger('MyLogger') In [644]: my_logger.setLevel(logging.DEBUG) In [645]: handler=logging.handlers.RotatingFileHandler(LOG_FILENAME,maxBytes=20,backupCount=5) In [646]: my_logger.addHandler(handler) In [648]: for i in range(20):     my_logger.debug('i=%d' % i)    .....:         .....:      In [650]: logfiles=glob.glob('%s*' %LOG_FILENAME) In [651]: for filename in logfiles:    .....:     print filename    .....:         .....:      /tmp/logging_rotatingfile_example.out.1 /tmp/logging_rotatingfile_example.out.2 /tmp/logging_rotatingfile_example.out.5 /tmp/logging_rotatingfile_example.out.3 /tmp/logging_rotatingfile_example.out.4 /tmp/logging_rotatingfile_example.out

最近的日志文件总是名为logging_rotatingfile_example.out，一旦大小达到maxBytes设置的20字节，就将轮转。

logging模块最重要的一个功能就是可以根据设置的不同的日志级别输出不同的日志信息。

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import logging import sys LEVELS={'debug':logging.DEBUG,         'info' :logging.INFO,         'warning':logging.WARNING,         'error':logging.ERROR,         'critical':logging.CRITICAL         } if 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 a info message') logging.warning('This is a warning message') logging.error('This is a error message') logging.critical('This is a critical error message') ~                                                                                                                         ~

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$ python logging_level_example.py debug DEBUG:root:This is a debug message INFO:root:This is a info message WARNING:root:This is a warning message ERROR:root:This is a error message CRITICAL:root:This is a critical error message $ python logging_level_example.py info INFO:root:This is a info message WARNING:root:This is a warning message ERROR:root:This is a error message CRITICAL:root:This is a critical error message $ python logging_level_example.py warning WARNING:root:This is a warning message ERROR:root:This is a error message CRITICAL:root:This is a critical error message $ python logging_level_example.py error ERROR:root:This is a error message CRITICAL:root:This is a critical error message $ python logging_level_example.py critical CRITICAL:root:This is a critical error message

logging模块包括logger，handler，filter和formatter。
Logger.setLevel()设置日志级别

Logger.addFilter()
Logger.removeFilter()
Logger.debug()
Logger.info()
Logger.warning()
Logger.error()
Logger.critical()
Logger.exception()
Logger.log()