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python 通过logging写入日志到文件和控制台的实例

yipeiwu_com5年前 (2020-03-06)Python基础

如下所示：

import logging 
 
# 创建一个logger 
logger = logging.getLogger('mylogger') 
logger.setLevel(logging.DEBUG) 
 
# 创建一个handler，用于写入日志文件 
fh = logging.FileHandler('test.log') 
fh.setLevel(logging.DEBUG) 
 
# 再创建一个handler，用于输出到控制台 
ch = logging.StreamHandler() 
ch.setLevel(logging.DEBUG) 
 
# 定义handler的输出格式 
formatter = logging.Formatter('[%(asctime)s][%(thread)d][%(filename)s][line: %(lineno)d][%(levelname)s] ## %(message)s')
fh.setFormatter(formatter) 
ch.setFormatter(formatter) 
 
# 给logger添加handler 
logger.addHandler(fh) 
logger.addHandler(ch) 
 
# 记录一条日志 
logger.info('foorbar')

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`.