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【轉(zhuǎn)】Python的標準logging模塊

Configuring Logging

Programmers can configure logging either by creating loggers, handlers, and formatters explicitly in a main module with the configuration methods listed above (using Python code), or by creating a logging config file. The following code is an example of configuring a very simple logger, a console handler, and a simple formatter in a Python module:

程序員可以顯示地通過在主模塊里面用上面列出的配置方法創(chuàng)建loggers,handlers和formatters的方式,或者,創(chuàng)建一個logging的配置文件的方式來配置logging.以下是一個非常簡單的配置logger的例子,一個python模塊里面包含了一個命令行handler和一個簡單的formmater:

import logging

#create logger

logger = logging.getLogger("simple_example")

logger.setLevel(logging.DEBUG)

#create console handler and set level to debug

ch = logging.StreamHandler()

ch.setLevel(logging.DEBUG)

#create formatter

formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s -

%(message)s")

#add formatter to ch

ch.setFormatter(formatter)

#add ch to logger

logger.addHandler(ch)

#"application" code

logger.debug("debug message")

logger.info("info message")

logger.warn("warn message")

logger.error("error message")

logger.critical("critical message")

Running this module from the command line produces the following output:

在在字符界面下運行上面的命令產(chǎn)生以下輸出:

jmjones@bean:~/logging $ python simple_logging_module.py

2005-03-19 15:10:26,618 - simple_example - DEBUG - debug message

2005-03-19 15:10:26,620 - simple_example - INFO - info message

2005-03-19 15:10:26,695 - simple_example - WARNING - warn message

2005-03-19 15:10:26,697 - simple_example - ERROR - error message

2005-03-19 15:10:26,773 - simple_example - CRITICAL - critical message

The following Python module creates a logger, handler, and formatter nearly identical to those in the example listed above, with the only difference being the names of the objects:

跟例子差不多,以下的Python模塊創(chuàng)建了一個logger,一個handler和一個formatter,這里僅僅換了換名字:

import logging

import logging.config

logging.config.fileConfig("logging.conf")

#create logger

logger = logging.getLogger("simpleExample")

#"application" code

logger.debug("debug message")

logger.info("info message")

logger.warn("warn message")

logger.error("error message")

logger.critical("critical message")

Here is the logging.conf file:

這里是logging.conf文件:

[loggers]

keys=root,simpleExample

[handlers]

keys=consoleHandler

[formatters]

keys=simpleFormatter

[logger_root]

level=DEBUG

handlers=consoleHandler

[logger_simpleExample]

level=DEBUG

handlers=consoleHandler

qualname=simpleExample

propagate=0

[handler_consoleHandler]

class=StreamHandler

level=DEBUG

formatter=simpleFormatter

args=(sys.stdout,)

[formatter_simpleFormatter]

format=%(asctime)s - %(name)s - %(levelname)s - %(message)s

datefmt=

The output is nearly identical to that of the non-config-file-based example:

輸出跟沒有配置文件的例子完全一樣:

jmjones@bean:~/logging $ python simple_logging_config.py

2005-03-19 15:38:55,977 - simpleExample - DEBUG - debug message

2005-03-19 15:38:55,979 - simpleExample - INFO - info message

2005-03-19 15:38:56,054 - simpleExample - WARNING - warn message

2005-03-19 15:38:56,055 - simpleExample - ERROR - error message

2005-03-19 15:38:56,130 - simpleExample - CRITICAL - critical message

The config file approach has a few advantages over the Python code approach. The first is the separation of configuration and code. The second is the ability of noncoders to easily modify the logging properties. The third is the really cool listen() method, which causes the application to listen on a socket for new configurations--and will update configurations at runtime without forcing you to restart the application!

用配置文件的方法比直接在Python代碼里面寫有幾個好處.第一個好處是配置和代碼的分離.第二個好處是即使看不懂程序也能方便的更改logging的屬性.第三個好處是”最酷的listen()方法”,用這個方法可以讓你的應(yīng)用程序在一個socket上監(jiān)聽新的配置信息 -- 可以直接在運行時改變配置而用不著重啟你的應(yīng)用~!

Here is a slight modification of the previous config file-based script:

這里是一個簡單的基于上面配置文件的腳本:

#!/usr/bin/env python

import logging

import logging.config

import time

import os

#specify logging config file

logging.config.fileConfig("logging.conf")

#create and start listener on port 9999

t = logging.config.listen(9999)

t.start()

#create logger

logger = logging.getLogger("simpleExample")

#watch for existence of file named "f"

#loop through the code while this file exists

while os.path.isfile('f'):

logger.debug("debug message")

logger.info("info message")

logger.warn("warn message")

logger.error("error message")

logger.critical("critical message")

time.sleep(5)

#cleanup

logging.config.stopListening()

t.join()

That was simple enough. Unfortunately, figuring out what format the config file needs to be took some investigation. The only useful information that I found in the Python Standard Library Reference documentation was in the logging configuration section under the listen() method:

夠簡單了吧!不幸地是,理解這個配置文件需要進行些研究.我僅僅在Python的標準庫文檔logging配置一節(jié)里面的listen()方法找到一點有用的信息:

Logging configurations will be sent as a file suitable for processing by fileConfig().

Logging配置會作為一個能被fileConfig()方法處理的文件發(fā)送.

Pushing a filename did not work. Pushing the contents of a config file did not work. I had to dig into the source a little. The docstring for the logging socket server's handle() method is:

用文件名不行,用配置文件的內(nèi)容也不行.我不得不深入一下源碼logging socket服務(wù)器的handler()方法的docstring是這樣寫的:

Handle a request.

Each request is expected to be a 4-byte length,

followed by the config file. Uses fileConfig() to do the

grunt work.

處理一個請求.

每個請求都應(yīng)該是4-byte長,后面跟一個配置文件.用fileConfig()方法完成剩下的工作.

This struck me as a bit odd. Does that mean you can send lengths only for config files of up to 9,999 bytes? Converting the length of the config file to a string did not work either. I looked farther down in the source code of the handle() method. Aaahh. It does a struct.unpack(), so the socket expects the first 4 bytes to be packed binary data. I tried it this way and it worked. The following snippet of code sends the contents of the file named on the command line to localhost:9999:

這讓我感到有些奇怪.難道說只能發(fā)送長度大于9,999bytes的配置文件嗎?而且把一個配置文件的內(nèi)容轉(zhuǎn)化成一個字符串也是不起作用.我又看了一下handler()方法的源碼.哈.它其實做了struct.unpack()!,所以socket才要求前面4個bytes打包二進制的數(shù)據(jù).我用這種方式重新試了一下,可以了.下面的代碼片斷把指定的文件內(nèi)容通過字符界面發(fā)送到了localhost:9999端口:

#!/usr/bin/env python

import socket

import sys

import struct

HOST = 'localhost'

PORT = 9999

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

print "connecting

s.connect((HOST, PORT))

print "connected

data_to_send = open(sys.argv[1], "r").read()

print "sending length

s.send(struct.pack(">L", len(data_to_send)))

print "sending data

s.send(data_to_send)

print "closing

s.close()

文章轉(zhuǎn)自：http://crazier9527.iteye.com/blog/290026
參考：
http://crazier9527.iteye.com/blog/290024
http://crazier9527.iteye.com/blog/290018
http://crazier9527.iteye.com/blog/290027

posted on 2011-08-12 14:49 XXXXXX 閱讀(1213) 評論(0) 編輯收藏所屬分類: Python

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【轉(zhuǎn)】Python的標準logging模塊