python logging模組學習(轉)

標籤：view   key   官方文檔   gre   system   for   系統   obb   logs   

前言

日誌是非常重要的，最近有接觸到這個，所以系統的看一下Python這個模組的用法。本文即為Logging模組的用法簡介，主要參考文章為Python官方文檔，連結見參考列表。

另外，Python的HOWTOs文檔很詳細，連日誌該怎麼用都寫了，所以有英文閱讀能力的同學建議去閱讀一下。

Logging模組構成組成

主要分為四個部分：

• Loggers：提供應用程式直接使用的介面
• Handlers：將Loggers產生的日誌傳到指定位置
• Filters：對輸出日誌進行過濾
• Formatters：控制輸出格式

記錄層級

Level	Numeric value	When it’s used
DEBUG	10	Detailed information, typically of interest only when diagnosing problems.
INFO	20	Confirmation that things are working as expected.
WARNING	30	An indication that something unexpected happened, or indicative of some problem in the near future (e.g. ‘disk space low’). The software is still working as expected.
ERROR	40	Due to a more serious problem, the software has not been able to perform some function.
CRITICAL	50	A serious error, indicating that the program itself may be unable to continue running.
NOSET	0	getattr(logging, loglevel.upper())

預設層級是WARNING，可以使用列印到螢幕上的方式記錄，也可以記錄到檔案中。

模組使用樣本簡單例子列印輸出

In [5]: import loggingIn [6]: logging.warning("FBI warning")WARNING:root:FBI warningIn [7]: logging.info("information")# 沒有列印是因為預設層級是warning

輸出到檔案中

In [4]: import loggingIn [5]: logging.basicConfig(filename=‘example.log‘, level=logging.DEBUG)In [6]: logging.debug("debug")In [7]: logging.warning(‘warning‘)In [8]: logging.info(‘info‘)In [9]: lsC++ STL/     a.py         example.log  parser/      test.sh*In [10]: cat example.logDEBUG:root:debugWARNING:root:warningINFO:root:infoIn [14]: logging.warning(‘new warning‘)# 注意這種是直接往後面添加，也就是add的，若是想覆蓋內容可以變更檔寫入方式In [15]: cat example.logDEBUG:root:debugWARNING:root:warningINFO:root:infoWARNING:root:new warning# 覆蓋的方式寫入例子(test) ?  test ipythonWARNING: Attempting to work in a virtualenv. If you encounter problems, please install IPython inside the virtualenv.Python 2.7.11 (default, Jun 17 2016, 20:01:51)Type "copyright", "credits" or "license" for more information.IPython 4.2.0 -- An enhanced Interactive Python.?         -> Introduction and overview of IPython‘s features.%quickref -> Quick reference.help      -> Python‘s own help system.object?   -> Details about ‘object‘, use ‘object??‘ for extra details.In [1]: import loggingIn [2]: logging.basicConfig(filename=‘example.log‘, filemode=‘w‘, level=logging.DEBUG)In [3]: logging.warning(‘FBI warning‘)In [4]: lsC++ STL/     a.py         example.log  parser/      test.sh*In [5]: cat example.logWARNING:root:FBI warningIn [6]: quit(test) ?  test ipythonWARNING: Attempting to work in a virtualenv. If you encounter problems, please install IPython inside the virtualenv.Python 2.7.11 (default, Jun 17 2016, 20:01:51)Type "copyright", "credits" or "license" for more information.IPython 4.2.0 -- An enhanced Interactive Python.?         -> Introduction and overview of IPython‘s features.%quickref -> Quick reference.help      -> Python‘s own help system.object?   -> Details about ‘object‘, use ‘object??‘ for extra details.In [1]: import loggingIn [2]: logging.basicConfig(filename=‘example.log‘, filemode=‘w‘, level=logging.DEBUG)In [3]: logging.warning(‘warning‘)In [4]: cat example.logWARNING:root:warning

變數的使用

和print語句中使用變數一樣，如:

In [5]: logging.warning(‘%s before you %s‘, ‘Look‘, ‘leap!‘)In [6]: cat example.logWARNING:root:warningWARNING:root:Look before you leap!

輸出格式

可以在basicConfig中設定，參數名稱可以參見連結，可以設定時間什麼的，如：

In [2]: import loggingIn [3]: logging.basicConfig(format=‘%(asctime)s:%(levelname)s:%(message)s‘, level=logging.DEBUG)In [4]: logging.warning(‘And this, too‘)2016-12-06 15:40:43,577:WARNING:And this, too

進階使用

當想項目中使用logging模組的時候肯定不能在這樣一句句的寫了，一般可能會抽象出一個模組來，這樣比較有效一些。logging模組提供了四個類（Loggers，Formatters，Filtters,Handlers）來實現不同的功能，與此對應的我們如果想封裝一個函數，也就要針對這幾個功能來自訂一下。

想自訂的話思路也很簡單，首先執行個體化一個相應的對象，然後進行一些設定，可以簡單看一下下面的例子：

import logging# create loggerlogger = logging.getLogger(‘simple_example‘)logger.setLevel(logging.DEBUG)# create console handler and set level to debugch = logging.StreamHandler()ch.setLevel(logging.DEBUG)# create formatterformatter = logging.Formatter(‘%(asctime)s - %(name)s - %(levelname)s - %(message)s‘)# add formatter to chch.setFormatter(formatter)# add ch to loggerlogger.addHandler(ch)# ‘application‘ codelogger.debug(‘debug message‘)logger.info(‘info message‘)logger.warn(‘warn message‘)logger.error(‘error message‘)logger.critical(‘critical message‘)# 輸出是：$ python simple_logging_module.py2005-03-19 15:10:26,618 - simple_example - DEBUG - debug message2005-03-19 15:10:26,620 - simple_example - INFO - info message2005-03-19 15:10:26,695 - simple_example - WARNING - warn message2005-03-19 15:10:26,697 - simple_example - ERROR - error message2005-03-19 15:10:26,773 - simple_example - CRITICAL - critical message

從設定檔匯入配置

模組內容：

import loggingimport logging.configlogging.config.fileConfig(‘logging.conf‘)# create loggerlogger = logging.getLogger(‘simpleExample‘)# ‘application‘ codelogger.debug(‘debug message‘)logger.info(‘info message‘)logger.warn(‘warn message‘)logger.error(‘error message‘)logger.critical(‘critical message‘)# 輸出$ python simple_logging_config.py2005-03-19 15:38:55,977 - simpleExample - DEBUG - debug message2005-03-19 15:38:55,979 - simpleExample - INFO - info message2005-03-19 15:38:56,054 - simpleExample - WARNING - warn message2005-03-19 15:38:56,055 - simpleExample - ERROR - error message2005-03-19 15:38:56,130 - simpleExample - CRITICAL - critical message

設定檔內容：

[loggers]keys=root,simpleExample[handlers]keys=consoleHandler[formatters]keys=simpleFormatter[logger_root]level=DEBUGhandlers=consoleHandler[logger_simpleExample]level=DEBUGhandlers=consoleHandlerqualname=simpleExamplepropagate=0[handler_consoleHandler]class=StreamHandlerlevel=DEBUGformatter=simpleFormatterargs=(sys.stdout,)[formatter_simpleFormatter]format=%(asctime)s - %(name)s - %(levelname)s - %(message)s

同時也可以使用YAML格式的設定檔，如：

version: 1formatters:  simple:    format: ‘%(asctime)s - %(name)s - %(levelname)s - %(message)s‘handlers:  console:    class: logging.StreamHandler    level: DEBUG    formatter: simple    stream: ext://sys.stdoutloggers:  simpleExample:    level: DEBUG    handlers: [console]    propagate: noroot:  level: DEBUG  handlers: [console]

PS

Logging模組使用也會有很多坑，常見的是日誌重複列印的問題，大家可以搜一下，這裡提供一些連結供參考：

1. http://www.jianshu.com/p/25f70905ae9d
2. https://yinzo.github.io/14610807170718.html
3. http://python.jobbole.com/86887/

參考

1. https://docs.python.org/2/library/logging.html
2. https://docs.python.org/2/howto/logging.html#logging-basic-tutorial

轉自http://www.cnblogs.com/wswang/p/6138304.html

python logging模組學習(轉)