输出到console(默认打印warning级别以上（warnging、error、critical）的日志)：
import logging
logging.debug('hello world') logging.warning('hello world') logging.error('hello world') #WARNING:root:hello world #ERROR:root:hello world
输出到文件：
import logging logging.basicConfig(filename='log_test.log',level=logging.INFO) logging.debug('helloworld') logging.info('helloworld') logging.warning('helloworld')
#INFO:root:helloworld
#WARNING:root:helloworld
输出到文件，设定格式：
import logging logging.basicConfig(filename='log_test.log',level=logging.INFO,format='%(asctime)s %(message)s',datefmt='%m-%d-%Y %I:%M:%S %p') logging.debug('helloworld') logging.info('helloworld') logging.warning('helloworld') #08-02-2020 05:56:53 AM helloworld #08-02-2020 05:56:53 AM helloworld
输出到文件，所有格式：
import logging logging.basicConfig(filename='log_test.log',level=logging.INFO,format='%(asctime)s %(message)s %(levelno)s %(levelname)s %(pathname)s %(filename)s %(module)s %(funcName)s %(lineno)d %(created)f %(relativeCreated)d %(asctime)s ' '%(thread)d %(threadName)s %(process)d )',datefmt='%m-%d-%Y %I:%M:%S %p') logging.debug('helloworld') logging.info('helloworld') logging.warning('helloworld') def test_log(): logging.warning('func test') test_log() #08-02-2020 06:20:59 AM helloworld 20 INFO E:/pythondir/Day01/testsdsd.py testsdsd.py testsdsd <module> 36 1596320459.622015 2 08-02-2020 06:20:59 AM 18572 MainThread 19432) #08-02-2020 06:20:59 AM helloworld 30 WARNING E:/pythondir/Day01/testsdsd.py testsdsd.py testsdsd <module> 37 1596320459.622015 2 08-02-2020 06:20:59 AM 18572 MainThread 19432) #08-02-2020 06:20:59 AM func test 30 WARNING E:/pythondir/Day01/testsdsd.py testsdsd.py testsdsd test_log 39 1596320459.622015 2 08-02-2020 06:20:59 AM 18572 MainThread 19432)
格式说明：
同时输出日志到console以及文本：
import logging #1.生成logger对象 logger = logging.getLogger('Mysql') #全局日志级别,(总过滤) logger.setLevel(logging.DEBUG) #2.生成handler对象 ch = logging.StreamHandler() #局部日志级别，(次级过滤) ch.setLevel(logging.INFO) fh = logging.FileHandler(filename='log_test_logging') #局部日志级别，(次级过滤) fh.setLevel(logging.WARNING) #2.1把handler对象绑定到logger logger.addHandler(ch) logger.addHandler(fh) #3.生成format对象,并设定日志格式 file_formatter = logging.Formatter('%(asctime)s %(name)s %(levelname)s %(message)s ') console_formatter = logging.Formatter('%(asctime)s %(name)s %(levelname)s %(message)s ') #3.1把formatter对象绑定handler对象 ch.setFormatter(console_formatter) fh.setFormatter(file_formatter) #日志输出 logger.warning('warning test') logger.debug('debug test')
对日志进行过滤以及切割：
import logging from logging import handlers #创建过滤对象类 class IgnoreBackupLogFilter(logging.Filter): def filter(self, record): return "you" not in record.getMessage() # 1.先生成logger logger = logging.getLogger('beifen') # logger.setLevel(logging.WARNING) logger.addFilter(IgnoreBackupLogFilter()) # 2.生成handler对象 ch = logging.StreamHandler() #普通文件对象 # fh = logging.FileHandler(filename='beifen_test') #切割文件对象 fh = handlers.RotatingFileHandler(filename='beifen_test',maxBytes=10,backupCount=3 ) # 2.1把handler对象绑定到logger logger.addHandler(ch) logger.addHandler(fh) # 3.生成formatter ch_formatter = logging.Formatter('%(asctime)s %(message)s') fh_formatter = logging.Formatter('%(asctime)s %(message)s') # 3.1 把formatter绑定到handler ch.setFormatter(ch_formatter) fh.setFormatter(fh_formatter) # 输出 logger.warning('hello you') logger.critical('hha')