Python如何记录日志

python的日志记录非常简单，短短几行代码就能实现日志记录，注释比较清楚了，不详细解释了。

Python代码  

#encoding: utf-8
import logging
#获取日志对象，可以带名字，不带名字返回root Logger
logger = logging.getLogger()
#定义一个文件句柄
file=logging.FileHandler("log.txt")
logger.addHandler(file)
#定义格式器，时间，日志级别，消息
formatter=logging.Formatter("%(asctime)s %(levelname)s %(message)s")
file.setFormatter(formatter)
#设置为记录任何日志，logging提供多种级别的日志信息，如：NOTSET, DEBUG, INFO, WARNING, ERROR, CRITICAL等
logger.setLevel(logging.NOTSET)
for i in range(0,10):
    logger.info(str(i))

关于formatter的配置，采用的是%(<dict key>)s的形式，就是字典的关键字替换。提供的关键字包括：

Format	Description
%(name)s	Name of the logger (logging channel).
%(levelno)s	Numeric logging level for the message (DEBUG, INFO, WARNING, ERROR, CRITICAL).
%(levelname)s	Text logging level for the message ('DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL').
%(pathname)s	Full pathname of the source file where the logging call was issued (if available).
%(filename)s	Filename portion of pathname.
%(module)s	Module (name portion of filename).
%(funcName)s	Name of function containing the logging call.
%(lineno)d	Source line number where the logging call was issued (if available).
%(created)f	Time when the LogRecord was created (as returned by time.time()).
%(relativeCreated)d	Time in milliseconds when the LogRecord was created, relative to the time the logging module was loaded.
%(asctime)s	Human-readable time when the LogRecord was created. By default this is of the form “2003-07-08 16:49:45,896” (the numbers after the comma are millisecond portion of the time).
%(msecs)d	Millisecond portion of the time when the LogRecord was created.
%(thread)d	Thread ID (if available).
%(threadName)s	Thread name (if available).
%(process)d	Process ID (if available).
%(message)s	The logged message, computed as msg % args.