先贴上logger/handler/formatter/filter的用处(来源见参考中链接):
Loggers expose the interface that application code directly uses.
Handlers send the log records (created by loggers) to the appropriate destination.
Filters provide a finer grained facility for determining which log records to output.
Formatters specify the layout of log records in the final output.
配置日志的方便快捷的方法,支持将log输出到控制台(Console)或文件中,但只支持一种。用法如下:
import logging
logging.basicConfig(filename='test.log', level=logging.DEBUG)
logging.info('this is info log')
basicConfig(**kwargs)代码长这个样子:
root = RootLogger(WARNING)
Logger.root = root
Logger.manager = Manager(Logger.root)
def basicConfig(**kwargs):
# Add thread safety in case someone mistakenly calls
# basicConfig() from multiple threads
_acquireLock()
try:
if len(root.handlers) == 0:
filename = kwargs.get("filename")
if filename:
mode = kwargs.get("filemode", 'a')
hdlr = FileHandler(filename, mode)
else:
stream = kwargs.get("stream")
hdlr = StreamHandler(stream)
fs = kwargs.get("format", BASIC_FORMAT)
dfs = kwargs.get("datefmt", None)
fmt = Formatter(fs, dfs)
hdlr.setFormatter(fmt)
root.addHandler(hdlr)
level = kwargs.get("level")
if level is not None:
root.setLevel(level)
finally:
_releaseLock()
可以看到,是先根据传入的内容,创建了logger(root),又创建了相应的handler(FileHandler和StreamHandler,前者输入log到文件,后者输入到console),并为已创建的的handler设置格式(hdlr.setFormatter(fmt)),然后将创建的handler加入到logger中(root.addHandler(hdlr)),最后为logger设置日志级别(root.setLevel(level))。
由上可见basicConfig()是将日志配置的一些方法封装了起来。
下面的例子实现将log同时输出到Console和日志文件,思路参考basicConfig():
import logging
logger = logging.getLogger()
logger.setLevel('DEBUG')
BASIC_FORMAT = "%(asctime)s:%(levelname)s:%(message)s"
DATE_FORMAT = '%Y-%m-%d %H:%M:%S'
formatter = logging.Formatter(BASIC_FORMAT, DATE_FORMAT)
chlr = logging.StreamHandler() # 输出到控制台的handler
chlr.setFormatter(formatter)
chlr.setLevel('INFO') # 也可以不设置,不设置就默认用logger的level
fhlr = logging.FileHandler('example.log') # 输出到文件的handler
fhlr.setFormatter(formatter)
logger.addHandler(chlr)
logger.addHandler(fhlr)
logger.info('this is info')
logger.debug('this is debug')
运行的结果:
# 控制台
2018-03-07 11:08:54:INFO:this is info
# example.log
2018-03-07 11:08:54:INFO:this is info
2018-03-07 11:08:54:DEBUG:this is debug
level | Numeric value |
---|---|
critical | 50 |
error | 40 |
warning | 30 |
info | 20 |
debug | 10 |
notset | 0 |
举例:目前日志级别设置为INFO,则除了DEBUG的日志不会打印外,其他的都会打印出来。
参考:
https://docs.python.org/3/library/logging.html
https://docs.python.org/3/howto/logging.html#logging-basic-tutorial