第一种：
import logging
logger = logging.getLogger(__name__)
logger.setLevel(level = logging.DEBUG)
fh = logging.FileHandler(log_file)
fh.setLevel(logging.DEBUG)
file_formatter = logging.Formatter('%(asctime)st%(levelname)st%(name)st%(message)s')
fh.setFormatter(file_formatter)
logger.addHandler(fh)
sh = logging.StreamHandler()
sh.setLevel(logging.INFO)
stream_formatter = logging.Formatter('%(asctime)s|%(levelname)s|%(message)s')
sh.setFormatter(stream_formatter)
logger.addHandler(sh)
第二种，这种写法好像会导致后续handler的日志会先被根过滤器的level设置过滤掉：
import logging
# 输出日志到文件,filename有参数时，日志不再输出屏幕，需要另建StreamHandler对象，输出屏幕
logging.basicConfig(format='%(asctime)s : %(levelname)s : %(message)s', level=logging.INFO,filename=log_file)
logger = logging.getLogger() #root logger
formatter = logging.Formatter('%(asctime)s|%(levelname)s|%(message)s')
StreamHandler = logging.StreamHandler()
StreamHandler.setLevel(logging.WARNING)
StreamHandler.setFormatter(formatter)
logger.addHandler(StreamHandler)
