[python]使用 python 编写日志模块

本篇文章主要介绍一下，如何使用 python 来编写属于自己的日志模块

1. 使用 python 来实现多线程并发写日志文件

from     threading import Thread

import     logging
from     logging        import handlers
from     logging.handlers import RotatingFileHandler
from     logging      import Formatter

from     time      import sleep
import     time


LOG_LEVEL = {
'default'     :logging.DEBUG,
'debug'        :logging.DEBUG,
'info'        :logging.INFO,
'warning'    :logging.WARNING,
'error'        :logging.ERROR,
'critical'    :logging.CRITICAL }

LOG_FILENAME     = ''
LOG_BACKUP_COUNTER = 3
LOG_TYPE = 'default'
LOG_MAX_SIZE = 1024*1024*4 # bits = 0.5MB of each log file


def InitLogger(log_file_name, logger):
    str_time      = time.strftime("%Y%m%d_%H%M%S")
    LOG_FILENAME = str_time+'_'+log_file_name
    #print(LOG_FILENAME)

    handler = RotatingFileHandler( LOG_FILENAME,maxBytes = LOG_MAX_SIZE, backupCount = LOG_BACKUP_COUNTER)

    # method indefault
    # handler = FileHandler( LOG_FILENAME)

    # set log file output message format
    fmt = '[ %(asctime)s ]--[ %(filename)s:%(lineno)s ]--[%(name)s]--[%(levelname)s]--[ %(message)s ]'

    formatter = Formatter (fmt)

    handler.setFormatter( formatter )

    logger.addHandler(handler)

    logger.setLevel(LOG_LEVEL.get(LOG_TYPE.lower()))


    # after set every parameters , return logger
    return logger


#define a thread writer class
class log_writter(Thread):
     def __init__(self,threadName,file_name):

      self.log_file_name = file_name

      Thread.__init__(self,name = threadName)

      logger = logging.getLogger(self.log_file_name)

      self.logger = InitLogger(self.log_file_name,logger)



     def run(self):

         global i

          self.logger.info(self.log_file_name)

         while i in range(10):
            print '**** log writer '+self.log_file_name+' test ******'

            self.logger.info ('hello aimer')

            self.logger.debug ('hello kokia')

            self.logger.warning ('hello kylin-zhang')

            i += 1

            time.sleep (3)

      print('end of log file test '+ self.log_file_name )




i = 0

threadCounter = 2400

for j in range(threadCounter):

   # s is used for thread and log file no.
   s = 'thread'
   s +='_'+str(j)

   print ( s )

   log_file = str(j)+'_mylog.log'
   my_logger = log_writter( s , log_file)
   my_logger.start ()

运行方法:
python  myLogger.py

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2. 将编写的日志模块简单修改之后应用在实际项目代码中

在这个地方会涉及到这样一个问题：
如何将一个路径下面的 .py 文件中定义的方法引入到另一个 .py 文件中
解决方法很简单：
举例来说，我们要在 node.py 中使用 myLogger.py 中定义并且实现的 InitLogger 这个方法
|------ myLogger.py
|------ node_id.py 

首先在需要引入的 .py 文件（myLogger.py）路径下面创建一个名为 __init__.py 的文件即可(空文件就可以，
python 会将含有该文件的文件夹当做是一个模块--->module)
|--- myLogger.py
|--- __init__.py (刚刚创建)
|--- node_id.py

然后在 node_in.py 文件中的开头部分添加引入 myLogger.py 以及引入文件中某个方法的声明语句 :
from myLogger import InitLogger
即可

如果要将日志模块添加到代码中，需要对刚刚编写的 myLogger.py 文件中多线程类和后面调用多线程来写日志的代码进行注释
使用 '''''''  便可以实现注释的功能

// another version of myLogger.py 
// myLogger.py

from     threading import Thread

import     logging
from     logging        import handlers
from     logging.handlers import RotatingFileHandler
from     logging      import Formatter

from     time      import sleep
import     time


LOG_LEVEL = {
'default'     :logging.DEBUG,
'debug'        :logging.DEBUG,
'info'        :logging.INFO,
'warning'    :logging.WARNING,
'error'        :logging.ERROR,
'critical'    :logging.CRITICAL }

LOG_FILENAME     = ''
LOG_BACKUP_COUNTER = 3
LOG_TYPE = 'default'
LOG_MAX_SIZE = 1024*1024*32 # bits = 4MB


def InitLogger(log_file_name, logger):
    str_time      = time.strftime("%Y%m%d_%H%M%S")
    LOG_FILENAME = str_time+'_'+log_file_name
    print(LOG_FILENAME)

    handler = RotatingFileHandler( LOG_FILENAME,maxBytes = LOG_MAX_SIZE, backupCount = LOG_BACKUP_COUNTER)

    # method indefault
    # handler = FileHandler( LOG_FILENAME)

    # set log file output message format
    fmt = '[ %(asctime)s ]--[ %(filename)s:%(lineno)s ]--[%(name)s]--[%(levelname)s]--[ %(message)s ]'

    formatter = Formatter (fmt)

    handler.setFormatter( formatter )

    logger.addHandler(handler)

    logger.setLevel(LOG_LEVEL.get(LOG_TYPE.lower()))


    # after set every parameters , return logger
    return logger

// node_id.py

from hashlib import sha1   # sha1() method
from random import randint # randint method

import logging

# here we test our logger
from myLogger import InitLogger

# here we define a method with name of get_node_id
# it will return a sha1 data with length = 20bytes = 8*20 = 160 bits
# it's namespace length = 20bytes = 160 bits  ,which means we could
# get a unique node id from 2^160 ids

def get_node_id():
    hash = sha1()
  # print hash just for test
  # print ( hash)
    s    = ""

    # we try to get a string with length of 20 bytes
    # and each byte in string is a random integer varied from 0 to 255
    for i in range(20):
        s += chr(randint(0,255))

    hash.update(s)     # insert s string into hash dict

  # print hash just for test
  # print ( hash )
  # print ( s )
  # here is the test of myLogger.py

    log_file_name = 'node_id.log'

    mylogger = logging.getLogger(log_file_name)
    mylogger = InitLogger(log_file_name , mylogger)

    mylogger.info('node id :'+hash.digest())


  # return hash's binary value
    return hash.digest ()

# test method
get_node_id()

end