python之强大的日志模块

1.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。

2.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

3.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 : INFO This is info message root : WARNING This is warning message

4.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

日志回滚方式，实际使用时用RotatingFileHandler和TimedRotatingFileHandler
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

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，
上述其它处理方式的使用请参见python2.5手册！

5.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')

We define a custom file-like object called StreamToLogger object which sends anything written to it to a logger instead. We then create two instances of that object and replace sys.stdout and sys.stderr with our fake file-like instances.

The output logfile looks like this:

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 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