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好好学Python：Python打印日志

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1. 输出日志到控制台

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import sys
import logging

log = logging.getLogger(__name__)
log.setLevel(logging.DEBUG)
log.addHandler(logging.StreamHandler(sys.stdout)) #默认sys.error

log.info('print info level log to console')

2. 输出日志到文件

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import sys
import logging

log = logging.getLogger(__name__)
log.setLevel(logging.DEBUG)
log.addHandler(logging.FileHandler('python.log'))

log.info('print info level log to file')

日志文件默认存储到执行命令的路径下，可以通过使用绝对路径来指定日志文件路径。

3. 封装日志模块

1、封装一个日志模块 log.py

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

import os
import logging
import logging.handlers

def init_log(log_path, level=logging.INFO, when="D", backup=7,
             format="%(levelname)s: %(asctime)s: %(filename)s:%(lineno)d * %(thread)d %(message)s",
             datefmt="%m-%d %H:%M:%S"):
    """
    init_log - initialize log module

    Args:
    log_path - Log file path prefix.
    Log data will go to two files: log_path.log and log_path.log.wf
    Any non-exist parent directories will be created automatically
    level - msg above the level will be displayed
    DEBUG < INFO < WARNING < ERROR < CRITICAL
    the default value is logging.INFO
    when - how to split the log file by time interval
    'S' : Seconds
    'M' : Minutes
    'H' : Hours
    'D' : Days
    'W' : Week day
    default value: 'D'
    format - format of the log
    default format:
    %(levelname)s: %(asctime)s: %(filename)s:%(lineno)d * %(thread)d %(message)s
    INFO: 12-09 18:02:42: log.py:40 * 139814749787872 HELLO WORLD
    backup - how many backup file to keep
    default value: 7

    Raises:
    OSError: fail to create log directories
    IOError: fail to open log file
    """
    formatter = logging.Formatter(format, datefmt)
    logger = logging.getLogger()
    logger.setLevel(level)

    dir = os.path.dirname(log_path)
    if not os.path.isdir(dir):
        os.makedirs(dir)

    handler = logging.handlers.TimedRotatingFileHandler(log_path + ".log",
                                                        when=when,
                                                        backupCount=backup)
    handler.setLevel(level)
    handler.setFormatter(formatter)
    logger.addHandler(handler)

    handler = logging.handlers.TimedRotatingFileHandler(log_path + ".log.wf",
                                                        when=when,
                                                        backupCount=backup)
    handler.setLevel(logging.WARNING)
    handler.setFormatter(formatter)
    logger.addHandler(handler)

2、使用日志模块

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

import os
import logging

import log

class VKTest(object):
    def __init__(self):
        logging.info('print info level log to file')

if __name__=="__main__":
    # 日志保存到./log/vk.log和./log/vk.log.wf，按天切割，保留7天
    log.init_log("./log/vk")
    logging.info("程序启动!!!")

    vk = VKTest()

    logging.info("程序结束!!!")

执行脚本后，日志内容会输出到 log/vk.log 中。

4. 封装日志模块2.0

1、封装一个日志模块 log.py

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

import os
import logging
import logging.handlers

DEFAULT_LOG_PATH = './log/'

class Log(object):

    def __init__(self,
                 logfile_name='default',
                 log_path=DEFAULT_LOG_PATH,
                 level=logging.INFO,
                 when="D",
                 backup=7,
                 format="%(levelname)s: %(asctime)s: %(filename)s:%(lineno)d * %(thread)d %(message)s",
                 datefmt="%m-%d %H:%M:%S"):
        """
        init_log - initialize log module

        Args:
        log_path - Log file path prefix.
        Log data will go to two files: log_path.log and log_path.log.wf
        Any non-exist parent directories will be created automatically
        level - msg above the level will be displayed
        DEBUG < INFO < WARNING < ERROR < CRITICAL
        the default value is logging.INFO
        when - how to split the log file by time interval
        'S' : Seconds
        'M' : Minutes
        'H' : Hours
        'D' : Days
        'W' : Week day
        default value: 'D'
        format - format of the log
        default format:
        %(levelname)s: %(asctime)s: %(filename)s:%(lineno)d * %(thread)d %(message)s
        INFO: 12-09 18:02:42: log.py:40 * 139814749787872 HELLO WORLD
        backup - how many backup file to keep
        default value: 7

        Raises:
        OSError: fail to create log directories
        IOError: fail to open log file
        """
        formatter = logging.Formatter(format, datefmt)
        # getLogger一定要传参，否则多次调用对象创建，得到的会是同一个logger对象
        # 后果就是相同的日志内容，会同时写到多个不同的日志文件中
        self.logger = logging.getLogger(logfile_name)
        self.logger.setLevel(level)

        if not os.path.exists(log_path):
            os.makedirs(log_path)
            
        common_log = os.path.join(log_path, logfile_name + ".log")
        handler = logging.handlers.TimedRotatingFileHandler(common_log,
                                                            when=when,
                                                            backupCount=backup)
        handler.setLevel(level)
        handler.setFormatter(formatter)
        self.logger.addHandler(handler)

        wf_log = os.path.join(log_path, logfile_name + ".log.wf")
        handler = logging.handlers.TimedRotatingFileHandler(wf_log,
                                                            when=when,
                                                            backupCount=backup)
        handler.setLevel(logging.WARNING)
        handler.setFormatter(formatter)
        self.logger.addHandler(handler)

    def get_logger(self):
        return self.logger

    # 同时输出内容到日志和控制台
    def get_console_logger(self):
        self.logger.addHandler(logging.StreamHandler(sys.stdout))
        return self.logger

2、使用日志模块

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

import os
import log

# 日志保存到./log/vk.log和./log/vk.log.wf，按天切割，保留7天
logger = log.Log(logfile_name='vk').get_logger()
# logger = log.Log(logfile_name='vk').get_console_logger()

class VKTest(object):
    def __init__(self):
        logger.info('print info level log to file')

if __name__=="__main__":
    logger.info("程序启动!!!")
    vk = VKTest()
    logger.info("程序结束!!!")

执行脚本后，日志内容会输出到 log/vk.log 中。

5. 参考文档

  • 本文作者： 好好学习的郝
  • 原文链接： https://www.voidking.com/dev-python-log/
  • 版权声明： 本文采用 BY-NC-SA 许可协议，转载请注明出处！源站会即时更新知识点并修正错误，欢迎访问~

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