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1. 简单配置

使用logging.basicConfig进行配置

#!/usr/local/bin/python
# -*- coding:utf-8 -*-
import logging
 
# 通过下面的方式进行简单配置输出方式与日志级别
logging.basicConfig(filename='logger.log', level=logging.INFO)
 
logging.debug('debug message')
logging.info('info message')
logging.warning('warn message')
logging.error('error message')
logging.critical('critical message')

代码创建了一个logger.log文件，文件中写入如下内容

INFO:root:info message
WARNING:root:warn message
ERROR:root:error message
CRITICAL:root:critical message

如果多次运行该函数，log文件会持续追加
basicConfig可以包含有如下参数，下面是官方文档

    Do basic configuration for the logging system.

    This function does nothing if the root logger already has handlers
    configured, unless the keyword argument *force* is set to ``True``.
    It is a convenience method intended for use by simple scripts
    to do one-shot configuration of the logging package.

    The default behaviour is to create a StreamHandler which writes to
    sys.stderr, set a formatter using the BASIC_FORMAT format string, and
    add the handler to the root logger.

    A number of optional keyword arguments may be specified, which can alter
    the default behaviour.

    filename  Specifies that a FileHandler be created, using the specified
              filename, rather than a StreamHandler.
    filemode  Specifies the mode to open the file, if filename is specified
              (if filemode is unspecified, it defaults to 'a').
    format    Use the specified format string for the handler.
    datefmt   Use the specified date/time format.
    style     If a format string is specified, use this to specify the
              type of format string (possible values '%', '{', '$', for
              %-formatting, :meth:`str.format` and :class:`string.Template`
              - defaults to '%').
    level     Set the root logger level to the specified level.
    stream    Use the specified stream to initialize the StreamHandler. Note
              that this argument is incompatible with 'filename' - if both
              are present, 'stream' is ignored.
    handlers  If specified, this should be an iterable of already created
              handlers, which will be added to the root handler. Any handler
              in the list which does not have a formatter assigned will be
              assigned the formatter created in this function.
    force     If this keyword  is specified as true, any existing handlers
              attached to the root logger are removed and closed, before
              carrying out the configuration as specified by the other
              arguments.
    Note that you could specify a stream created using open(filename, mode)
    rather than passing the filename and mode in. However, it should be
    remembered that StreamHandler does not close its stream (since it may be
    using sys.stdout or sys.stderr), whereas FileHandler closes its stream
    when the handler is closed.

2. 使用FileHandler和Formatter进行配置

步骤如下

1. 创建logger对象
2. 创建FileHandler和Formatter对象
3. 使用FileHandler和Formatter对logger进行配置
   示例代码如下:

# -*- encoding:utf-8 -*-
import logging


# create logger
logger_name = "example"
logger = logging.getLogger(logger_name)
logger.setLevel(logging.DEBUG)
# create file handler
log_path = "./log.log"
fh = logging.FileHandler(log_path)
fh.setLevel(logging.WARN)
# create formatter
fmt = "%(asctime)-15s %(levelname)s %(filename)s %(lineno)d %(process)d %(message)s"
datefmt = "%a %d %b %Y %H:%M:%S"
formatter = logging.Formatter(fmt, datefmt)
# add handler and formatter to logger
fh.setFormatter(formatter)
logger.addHandler(fh)
# print log info
logger.debug('debug message')
logger.info('info message')
logger.warning('warn message')
logger.error('error message')
logger.critical('critical message')

注意: %(levelname)s 是python风格的格式化字符串，参考文章python格式化字符串

参考

• python配置logging
• python格式化字符串

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