模塊級函數
logging.getLogger([name]):返回一個logger對象，如果沒有指定名字將返回root logger
logging.debug()、logging.info()、logging.warning()、logging.error()、logging.critical()：設定root logger的日志級別
logging.basicConfig():用默認Formatter為日志系統建立一個StreamHandler，設置基礎配置并加到root logger中
示例：logging_level_example.py
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')
輸出：
$ 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):指定最低的日志級別，低于lel的級別將被忽略。debug是最低的內置級別，critical為最高
Logger.addFilter(filt)、Logger.removeFilter(filt):添加或刪除指定的filter
Logger.addHandler(hdlr)、Logger.removeHandler(hdlr)：增加或刪除指定的handler
Logger.debug()、Logger.info()、Logger.warning()、Logger.error()、Logger.critical()：可以設置的日志級別
示例：simple_logging_module.py
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")
輸出：
$ 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對象負責發送相關的信息到指定目的地。可以通過addHandler()方法添加多個多handler
Handler.setLevel(lel):指定被處理的信息級別，低于lel級別的信息將被忽略
Handler.setFormatter()：給這個handler選擇一個格式
Handler.addFilter(filt)、Handler.removeFilter(filt)：新增或刪除一個filter對象
Formatters
Formatter對象設置日志信息最后的規則、結構和內容，默認的時間格式為%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 | 數字形式的日志級別 |
%(levelname)s | 文本形式的日志級別 |
%(pathname)s | 調用日志輸出函數的模塊的完整路徑名，可能沒有 |
%(filename)s | 調用日志輸出函數的模塊的文件名 |
%(module)s | 調用日志輸出函數的模塊名 |
%(funcName)s | 調用日志輸出函數的函數名 |
%(lineno)d | 調用日志輸出函數的語句所在的代碼行 |
%(created)f | 當前時間，用UNIX標準的表示時間的浮 點數表示 |
%(relativeCreated)d | 輸出日志信息時的，自Logger創建以 來的毫秒數 |
%(asctime)s | 字符串形式的當前時間。默認格式是 “2003-07-08 16:49:45,896”。逗號后面的是毫秒 |
%(thread)d | 線程ID。可能沒有 |
%(threadName)s | 線程名。可能沒有 |
%(process)d | 進程ID。可能沒有 |
%(message)s | 用戶輸出的消息 |
最后來個完整例子：
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.')
運行后，在終端看到的結果
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.
在日志文件中的結果
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.
發現DEBUG信息只有在文件中出現，這是因為StreamHandler中setLevel是INFO，可以看出Logger.setLevel()和handler.setLevel()的區別詳細信息請參閱 http://docs.python.org/library/logging.html
