python logging 转载

logging 在任何一个 python 工程中都应该是默认配置。因此掌握 logging 模块是构写大型 python 程序必知必会。好在这个模块非常简单易用。

logging模块最初在 2.3 引入。

常用接口：

logging.getLogger(name) name 一般是一个由"."分割的层次值。比如 foo.bar.baz（当然也可以为foo），logging 的分层与pyhon 包的分层类似，其中 foo.bar,foo.bar.baz 都是 foo 子代。 如果多次指定相同的 name，后面只是前面的引用。 如果你写一个独立的模块，推荐用logging.getLogger(name)，在 python
包的命名空间中 name 是模块名。

简单的将日志打印到屏幕

import logging
logging.debug('This is debug message')
logging.info('This is info message')
logging.warning('This is warning message')

屏幕上打印: WARNING:root:This is warning message

默认情况下，logging将日志打印到屏幕，日志级别为WARNING； 日志级别大小关系为：CRITICAL > ERROR > WARNING > INFO > DEBUG > NOTSET，当然也可以自己定义日志级别。

通过logging.basicConfig函数对日志的输出格式及方式做相关配置

import logging
logging.basicConfig(level=logging.DEBUG,
format='%(asctime)s %(filename)s[line:%(lineno)d] %(levelname)s %(message)s',
datefmt='%a, %d %b %Y %H:%M:%S',
filename='myapp.log',
filemode='w')
logging.debug('This is debug message')
logging.info('This is info message')
logging.warning('This is warning message')

./myapp.log文件中内容为: Sun, 24 May 2009 21:48:54 demo2.py[line:11] DEBUG This is debug message Sun, 24 May 2009 21:48:54 demo2.py[line:12] INFO This is info message Sun, 24 May 2009 21:48:54 demo2.py[line:13] WARNING This is warning message

logging.basicConfig函数各参数:

filename: 指定日志文件名 filemode: 和file函数意义相同，指定日志文件的打开模式，'w'或'a' format: 指定输出的格式和内容，format可以输出很多有用信息，如上例所示: %(levelno)s: 打印日志级别的数值 %(levelname)s: 打印日志级别名称 %(pathname)s: 打印当前执行程序的路径，其实就是sys.argv[0] %(filename)s: 打印当前执行程序名 %(funcName)s: 打印日志的当前函数 %(lineno)d:
打印日志的当前行号 %(asctime)s: 打印日志的时间 %(thread)d: 打印线程ID %(threadName)s: 打印线程名称 %(process)d: 打印进程ID %(message)s: 打印日志信息 datefmt: 指定时间格式，同time.strftime() level: 设置日志级别，默认为logging.WARNING stream: 指定将日志的输出流，可以指定输出到sys.stderr,sys.stdout或者文件，默认输出到sys.stderr，当stream和filename同时指定时，stream被忽略

将日志同时输出到文件和屏幕

import logging
logging.basicConfig(level=logging.DEBUG,
format='%(asctime)s %(filename)s[line:%(lineno)d] %(levelname)s %(message)s',
datefmt='%a, %d %b %Y %H:%M:%S',
filename='myapp.log',
filemode='w')

定义一个StreamHandler，将INFO级别或更高的日志信息打印到标准错误，并将其添加到当前的日志处理对象

console = logging.StreamHandler()
console.setLevel(logging.INFO)
formatter = logging.Formatter('%(name)-12s: %(levelname)-8s %(message)s')
console.setFormatter(formatter)
logging.getLogger('').addHandler(console)

logging.debug('This is debug message')
logging.info('This is info message')
logging.warning('This is warning message')

屏幕上打印:

root: INFOThis is info message
root: WARNINGThis is warning message

./myapp.log文件中内容为: Sun, 24 May 2009 21:48:54 demo2.py[line:11] DEBUG This is debug message Sun, 24 May 2009 21:48:54 demo2.py[line:12] INFO This is info message Sun, 24 May 2009 21:48:54 demo2.py[line:13] WARNING This is warning message

logging之日志回滚

import logging
from logging.handlers import RotatingFileHandler

#定义一个RotatingFileHandler，最多备份5个日志文件，每个日志文件最大10M
Rthandler = RotatingFileHandler('myapp.log', maxBytes=10*1024*1024,backupCount=5)
Rthandler.setLevel(logging.INFO)
formatter = logging.Formatter('%(name)-12s: %(levelname)-8s %(message)s')
Rthandler.setFormatter(formatter)
logging.getLogger('').addHandler(Rthandler)

从上例和本例可以看出，logging有一个日志处理的主对象，其它处理方式都是通过addHandler添加进去的。

logging的几种handle方式如下：

logging.StreamHandler: 日志输出到流，可以是sys.stderr、sys.stdout或者文件

logging.FileHandler: 日志输出到文件

logging.handlers.BaseRotatingHandler

logging.handlers.RotatingFileHandler
logging.handlers.TimedRotatingFileHandler
logging.handlers.SocketHandler: 远程输出日志到TCP/IP sockets
logging.handlers.DatagramHandler: 远程输出日志到UDP sockets
logging.handlers.SMTPHandler: 远程输出日志到邮件地址
logging.handlers.SysLogHandler: 日志输出到syslog
logging.handlers.NTEventLogHandler: 远程输出日志到Windows NT/2000/XP的事件日志
logging.handlers.MemoryHandler: 日志输出到内存中的制定buffer
logging.handlers.HTTPHandler: 通过"GET"或"POST"远程输出到HTTP服务器
日志回滚方式，实际使用时用RotatingFileHandler和TimedRotatingFileHandler 由于StreamHandler和FileHandler是常用的日志处理方式，所以直接包含在logging模块中，而其他方式则包含在logging.handlers模块中，

通过logging.config模块配置日志

#logger.conf

[loggers]
keys=root,example01,example02
[logger_root]
level=DEBUG
handlers=hand01,hand02
[logger_example01]
handlers=hand01,hand02
qualname=example01
propagate=0
[logger_example02]
handlers=hand01,hand03
qualname=example02
propagate=0

[handlers]
keys=hand01,hand02,hand03
[handler_hand01]
class=StreamHandler
level=INFO
formatter=form02
args=(sys.stderr,)
[handler_hand02]
class=FileHandler
level=DEBUG
formatter=form01
args=('myapp.log', 'a')
[handler_hand03]
class=handlers.RotatingFileHandler
level=INFO
formatter=form02
args=('myapp.log', 'a', 10*1024*1024, 5)

[formatters]
keys=form01,form02
[formatter_form01]
format=%(asctime)s %(filename)s[line:%(lineno)d] %(levelname)s %(message)s
datefmt=%a, %d %b %Y %H:%M:%S
[formatter_form02]
format=%(name)-12s: %(levelname)-8s %(message)s
datefmt=

上例3： import logging import logging.config

logging.config.fileConfig("logger.conf")
logger = logging.getLogger("example01")

logger.debug('This is debug message')
logger.info('This is info message')
logger.warning('This is warning message')

上例4： import logging import logging.config

logging.config.fileConfig("logger.conf")
logger = logging.getLogger("example02")

logger.debug('This is debug message')
logger.info('This is info message')
logger.warning('This is warning message')

6.logging是线程安全的

7.logging重定向strerr,strout

import logging
import sys
class StreamToLogger(object):
"""   Fake file-like stream object that redirects writes to a logger instance.   """
def __init__(self, logger, log_level=logging.INFO):
self.logger = logger
self.log_level = log_level
self.linebuf = ''

def write(self, buf):
for line in buf.rstrip().splitlines():
self.logger.log(self.log_level, line.rstrip())

logging.basicConfig(
level=logging.DEBUG,
format='%(asctime)s:%(levelname)s:%(name)s:%(message)s',
filename="out.log",
filemode='a')

stdout_logger = logging.getLogger('STDOUT')
sl = StreamToLogger(stdout_logger, logging.INFO)
sys.stdout = sl

stderr_logger = logging.getLogger('STDERR')
sl = StreamToLogger(stderr_logger, logging.ERROR)
sys.stderr = sl

print "Test to standard out"
raise Exception('Test to standard error')

输出：

2011-08-14 14:46:20,573:INFO:STDOUT:Test to standard out
2011-08-14 14:46:20,573:ERROR:STDERR:Traceback (most recent call last):
2011-08-14 14:46:20,574:ERROR:STDERR:  File "redirect.py", line 33, in   2011-08-14 14:46:20,574:ERROR:STDERR:raise Exception('Test to standard error')
2011-08-14 14:46:20,574:ERROR:STDERR:Exception
2011-08-14 14:46:20,574:ERROR:STDERR::
2011-08-14 14:46:20,574:ERROR:STDERR:Test to standard error
2011-08-14 14:46:20,573:INFO:STDOUT:Test to standard out
2011-08-14 14:46:20,573:ERROR:STDERR:Traceback (most recent call last):
2011-08-14 14:46:20,574:ERROR:STDERR:  File "redirect.py", line 33, in 2011-08-14 14:46:20,574:ERROR:STDERR:raise Exception('Test http://blog.csdn.net/azhao_dn/article/details/7320186to standard error')
2011-08-14 14:46:20,574:ERROR:STDERR:Exception
2011-08-14 14:46:20,574:ERROR:STDERR::
2011-08-14 14:46:20,574:ERROR:STDERR:Test to standard error

class logging.Logger

Logger.propagate
Logger.setLevel(lvl)
Logger.isEnabledFor(lvl)
Logger.getEffectiveLevel()
Logger.getChild(suffix)
Logger.debug(msg, args, *kwargs)
Logger.info(msg, args, *kwargs)
Logger.warning(msg, args, *kwargs)
Logger.error(msg, args, *kwargs)
Logger.critical(msg, args, *kwargs)
Logger.log(lvl, msg, args, *kwargs)
Logger.exception(msg, *args)
Logger.addFilter(filt)
Logger.removeFilter(filt)
Logger.filter(record)
Logger.removeHandler(hdlr)
Logger.findCaller()
Logger.handle(record)
Logger.makeRecord(name, lvl, fn, lno, msg, args, exc_info, func=None, extra=None)
Handler Objects