08 日志模块

简单用法

import logging
logging.warning("user [mufeng] attempted wrong password more than 3 times")
logging.critical("server is down")

日志级别

数值越大，级别越高

CRITICAL = 50
FATAL = CRITICAL
ERROR = 40
WARNING = 30
WARN = WARNING
INFO = 20
DEBUG = 10
NOTSET = 0

level参数

参数值大于等于level才有效

import logging
logging.basicConfig(level=logging.INFO)
logging.debug('i am debug')
logging.info('i am info')
logging.warning('i am warning')

日志文件

一般来说，日志会写到文件，因为写到内存有太多不确定性，如项目运行停止，机器断电或重启等故障

import logging
logging.basicConfig(filename='log.txt', level=logging.INFO)
logging.debug('i am debug')
logging.info('i am info')
logging.warning('i am warning')

自定义日志格式

import logging
logging.basicConfig(format='%(asctime)s %(message)s', datefmt='%m/%d/%Y %I:%M:%S %p')
logging.warning('i am info')

除了加时间，还可以自定义一大堆格式，下表就是所有支持的格式

同时输出日志到屏幕和文件

import logging
# create logger
logger = logging.getLogger('TEST-LOG')
logger.setLevel(logging.DEBUG)
# create console handler and set level to debug
ch = logging.StreamHandler()
ch.setLevel(logging.DEBUG)
# create file handler and set level to warning
fh = logging.FileHandler("access.log")
fh.setLevel(logging.WARNING)
# create formatter
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
# add formatter to ch and fh
ch.setFormatter(formatter)
fh.setFormatter(formatter)
# add ch and fh to logger
logger.addHandler(ch)
logger.addHandler(fh)
# 'application' code
logger.debug('debug message')
logger.info('info message')
logger.warning('warn message')
logger.error('error message')
logger.critical('critical message')