logging 模块：记录日志

logging 模块可以用来记录日志：

import logging

logging 的日志类型有以下几种：

• logging.critical(msg)
• logging.error(msg)
• logging.warning(msg)
• logging.info(msg)
• logging.debug(msg)

级别排序为：CRITICAL > ERROR > WARNING > INFO > DEBUG > NOTSET

默认情况下，logging 的日志级别为 WARNING，只有不低于 WARNING 级别的日志才会显示在命令行。

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

# 不会显示
logging.info('This is info message')
logging.debug('This is debug message')

CRITICAL:root:This is critical message
ERROR:root:This is error message
WARNING:root:This is warning message

可以这样修改默认的日志级别：

logging.root.setLevel(level=logging.INFO)

logging.info('This is info message')

INFO:root:This is info message

可以通过 logging.basicConfig() 函数来改变默认的日志显示方式：

logging.basicConfig(format='%(asctime)s: %(levelname)s: %(message)s')

logger = logging.getLogger("this program")

logger.critical('This is critical message')

CRITICAL:this program:This is critical message