Python----logging模块的使用方法（python中logging模块）

Python----logging模块的使用方法（python中logging模块）

1 logging 日志级别

2 logging 默认的是warning级别

import logginglogging.debug("this is debug log")logging.info("this is info log")logging.warning("this is warning log")logging.error("this is error log")logging.critical("this is critical log")

执行结果如下：

WARNING:root:this is warning logERROR:root:this is error logCRITICAL:root:this is

3 可以通过logging.basicConfig(level=logging.DEBUG) 来设置日志级别

import logginglogging.basicConfig(level=logging.DEBUG)logging.debug("this is debug log")logging.info("this is info log")logging.warning("this is warning log")logging.error("this is error log")logging.critical("this is critical log")

运行结果如下：

DEBUG:root:this is debug logINFO:root:this is info logWARNING:root:this is warning logERROR:root:this is error logCRITICAL:root:this is

4 logging日志是一部写入的，logging打印的内容和print打印的内筒先后顺序是不一致的

import loggingprint("this is print log")logging.basicConfig(level=logging.DEBUG)logging.debug("this is debug log")logging.info("this is info log")logging.warning("this is warning log")logging.error("this is error log")logging.critical("this is critical log")

运行结果有可能是下面这种输出顺序

DEBUG:root:this is debug logINFO:root:this is info logWARNING:root:this is warning logERROR:root:this is error logCRITICAL:root:this is critical logthis is print

5 logging.basicConfig(filename=“demo.log”)可以指定日志文件名，默认在当前目录下生成文件，此时不再往屏幕打印日志，而是将日志信息输出到指定的日志文件中去

import loggingprint("this is print log")logging.basicConfig(filename="demo.log",level=logging.DEBUG)logging.debug("this is debug log")logging.info("this is info log")logging.warning("this is warning log")logging.error("this is error log")logging.critical("this is critical log")

运行后屏幕上输出结果为：

this is print

而在当前文件下生成了一个demo.log的日志文件，此日志文件的内容为：

DEBUG:root:this is debug logINFO:root:this is info logWARNING:root:this is warning logERROR:root:this is error logCRITICAL:root:this is

6 logging.basicConfig(filemode=‘w’) 可以指定日志文件的模式，w表示每次清空日志文件，重新写入，a表示在日志文件后面追加，默认的模式为a

将上述 5 中的实例代码再执行一次，demo.log中内容为：

DEBUG:root:this is debug logINFO:root:this is info logWARNING:root:this is warning logERROR:root:this is error logCRITICAL:root:this is critical logDEBUG:root:this is debug logINFO:root:this is info logWARNING:root:this is warning logERROR:root:this is error logCRITICAL:root:this is

若代码修改为如下，再执行：

import loggingprint("this is print log")logging.basicConfig(filename="demo.log",filemode='w',level=logging.DEBUG)logging.debug("this is debug log")logging.info("this is info log")logging.warning("this is warning log")logging.error("this is error log")logging.critical("this is critical log")

运行后，demo.log中的内容又恢复到如下内容：

DEBUG:root:this is debug logINFO:root:this is info logWARNING:root:this is warning logERROR:root:this is error logCRITICAL:root:this is

7 logging 向日志中写入变量的方式

import logginglogging.basicConfig(level=logging.DEBUG)name="zhangsan"age=20logging.debug("name: %s age: %d",name,age)logging.info("name: %s age: %d" %(name,age))logging.warning("name: {} age: {}".format(name,age))logging.error("name: {name} age: {age}".format(name=name,age=age))

运行结果如下：

DEBUG:root:name: zhangsan age: 20INFO:root:name: zhangsan age: 20WARNING:root:name: zhangsan age: 20ERROR:root:name: zhangsan age: 20

8 日志内容格式增加一些公共的内容

import logginglogging.basicConfig(format=("%(asctime)s | %(levelname)s | %(filename)s:%(lineno)s | %(message)s"), datefmt="%Y-%m-%d_%H:%M:%S", level=logging.DEBUG)name="zhangsan"age=20logging.debug("name: %s age: %d",name,age)logging.info("name: %s age: %d" %(name,age))logging.warning("name: {} age: {}".format(name,age))logging.error("name: {name} age: {age}".format(name=name,age=age))

运行结果为：

2020-08-03_07:20:42 | DEBUG | test1.py:9 | name: zhangsan age: 202020-08-03_07:20:42 | INFO | test1.py:10 | name: zhangsan age: 202020-08-03_07:20:42 | WARNING | test1.py:11 | name: zhangsan age: 202020-08-03_07:20:42 | ERROR | test1.py:12 | name: zhangsan age: 20

9 logging的高级应用

logging模块采用了模块化设计，主要包含四种组件

Loggers：记录器，提供应用程序代码能直接使用的接口Handlers：处理器，将记录器产生的日志发送到目的地Filters：过滤器，提供更好的粒度控制，决定哪些日志会被输出格式化器：设置内置内容的组成结构和消息字段

10 logging的高级应用流程

|---创建屏幕StreamHandler--设置日志等级---|创建一个logger并设置默认等级---| |----创建formatter----用formatter渲染所有的hansdler----将所有的handler加入logger内----程序调用logger |---创建文件FileHandler--设置日志等级-----|

11 loggers记录器

提供应用程序的调用接口logger=logging。getLogger(name) logger是单例的决定日志记录的级别logger.setLevel()将日志内容传递到相关联的handlers中logger.addHandler()logger。removeHandler()

12 handler处理器

StreamHandler标准输出stdout（如显示器）分发器创建方法： sh=logging.StreamHandler(stream=None)FileHandler将日志保存到磁盘文件的处理器创建方法：fh=logging.FileHandler(filename,mode=“a”,enconding=None,delay=False)setFormatter(): 设置当前handler对象使用的消息格斯

13 常用的Handlers处理器

StreamHandlerFileHandlerBaseRotatingHandlerRotatingHandlerTimedRotatingFileHandlerSocketHandlerDatagramHandlerSMTPHandlerSysLogHandlerNTEventLogHandlerHTTPHandlerWatchedFileHandlerQueueHandlerNullHandler

14 常见的formatter格式

15 下面两段代码的功能是完全一样的，使用logging直接调info、debug等日志与实例化一个默认的root logger是一样的，换言之，使用logging直接调日志方法的方式就是通过获取root日志来实现的

import logginglogging.debug("this is debug log")logging.info("this is info log")logging.warning("this is warning log")logging.error("this is error log")logging.critical("this is critical log")logger=logging.getLogger()logger.debug("this is debug log")logger.info("this is info log")logger.warning("this is warning log")logger.error("this is error log")logger.critical("this is critical log"

运行结果如下：

WARNING:root:this is warning logERROR:root:this is error logCRITICAL:root:this is critical logWARNING:root:this is warning logERROR:root:this is error logCRITICAL:root:this is

16 下面一段代码使用getLogger时指定一个名称，即实例化一个logger，然后设置两种处理器，分别往控制台和文件中写日志，还可以设置日志内容的格式，具体如下所示

import logginglogger=logging.getLogger("test")console_handler=logging.StreamHandler()console_handler.setLevel(logging.DEBUG)file_handler=logging.FileHandler(filename="demo.log")file_handler.setLevel(logging.DEBUG)formatter=logging.Formatter(fmt="%(asctime)s | %(levelname)s | %(filename)s:%(lineno)s | %(message)s")console_handler.setFormatter(formatter)file_handler.setFormatter(formatter)logger.addHandler(console_handler)logger.addHandler(file_handler)log=loggerlog.debug("this is debug log")log.info("this is info log")log.warning("this is warning log")log.error("this is error log")log.critical("this is critical log")

运行结果如下：

2020-08-04 23:08:56,625 | WARNING | test1.py:25 | this is warning log2020-08-04 23:08:56,625 | ERROR | test1.py:26 | this is error log2020-08-04 23:08:56,625 | CRITICAL | test1.py:27 | this is

并且在demo.log日志文件中写入了如下内容：

2020-08-04 23:08:56,625 | WARNING | test1.py:25 | this is warning log2020-08-04 23:08:56,625 | ERROR | test1.py:26 | this is error log2020-08-04 23:08:56,625 | CRITICAL | test1.py:27 | this is

17 上述 16 的日志打印明显与本来的期望是不一致的，本来期望控制台和文件都是设置了DEBUG级别，但实际上控制台和文件中都打印了Warning的级别的日志

这里需要注意的是，logger默认的日志级别是warning，而日志的最终级别将取决于logger和handler级别的最高级别，所以上述16中虽然控制台和文件handler的日志级别都设置了debug，但是因为logger默认级别是warning，所以最终打印的都是warning级别，下面一段代码将logger设置为debug级别，然后将控制台设置为info，将文件handler设置为warning，然后再看一下效果：

import logginglogger=logging.getLogger("test")logger.setLevel(logging.DEBUG)console_handler=logging.StreamHandler()console_handler.setLevel(logging.INFO)file_handler=logging.FileHandler(filename="demo.log")file_handler.setLevel(logging.WARNING)formatter=logging.Formatter(fmt="%(asctime)s | %(levelname)s | %(filename)s:%(lineno)s | %(message)s")console_handler.setFormatter(formatter)file_handler.setFormatter(formatter)logger.addHandler(console_handler)logger.addHandler(file_handler)log=loggerlog.debug("this is debug log")log.info("this is info log")log.warning("this is warning log")log.error("this is error log")log.critical("this is critical log")

运行结果如下：

2020-08-04 23:21:37,888 | INFO | test1.py:25 | this is info log2020-08-04 23:21:37,888 | WARNING | test1.py:26 | this is warning log2020-08-04 23:21:37,888 | ERROR | test1.py:27 | this is error log2020-08-04 23:21:37,888 | CRITICAL | test1.py:28 | this is

而在demo.log日志文件中写入了如下内容，此时与上述分析一致了

2020-08-04 23:21:37,888 | WARNING | test1.py:26 | this is warning log2020-08-04 23:21:37,888 | ERROR | test1.py:27 | this is error log2020-08-04 23:21:37,888 | CRITICAL | test1.py:28 | this is

18 定义filter并给控制台的handler加一个filter，过滤的name与日志名称不一致，如下代码，此时则不会往控制台写日志，但日志文件的日志还是正常写的

import logginglogger=logging.getLogger("test")logger.setLevel(logging.DEBUG)console_handler=logging.StreamHandler()console_handler.setLevel(logging.INFO)file_handler=logging.FileHandler(filename="demo.log")file_handler.setLevel(logging.WARNING)formatter=logging.Formatter(fmt="%(asctime)s | %(levelname)s | %(filename)s:%(lineno)s | %(message)s")console_handler.setFormatter(formatter)file_handler.setFormatter(formatter)logger.addHandler(console_handler)logger.addHandler(file_handler)filter=logging.Filter("test1")console_handler.addFilter(filter)log=loggerlog.debug("this is debug log")log.info("this is info log")log.warning("this is warning log")log.error("this is error log")log.critical("this is critical log")

此时运行后控制台结果为空，日志文件如下日志打印正常

2020-08-04 23:31:00,459 | WARNING | test1.py:29 | this is warning log2020-08-04 23:31:00,459 | ERROR | test1.py:30 | this is error log2020-08-04 23:31:00,459 | CRITICAL | test1.py:31 | this is

19 配置文件的方式

(1) 首先编写类似如下的log配置文件：logging.conf， 这里面定义了root和test两个logger

[loggers]keys=root,test[handlers]keys=fileHandler,consoleHandler[formatters];keys=simpleFormatter[logger_root]level=DEBUGhandlers=consoleHandler[logger_test]level=DEBUGhandlers=fileHandler,consoleHandlerqualname=testpropagate=0[handler_consoleHandler]class=StreamHandlerargs=(sys.stdout,)level=DEBUGformatter=simpleFormatter[handler_fileHandler]class=handlers.TimedRotatingFileHandlerargs=("test.log","midnight",1,0)level=DEBUGformatter=simpleFormatter[formatter_simpleFormatter]format=%(asctime)s|%(levelname)s|%(filename)s[line:%(lineno)d]|%(message)sdatafmt=%Y-%m-%d_%H:%M:%S

（2）然后在py文件中编写如下代码，这里演示了root的logger和test的logger两种的使用方式

import logging.configlogging.config.fileConfig("logging.conf")logger=logging.getLogger("test")log=loggerlog.debug("this is debug log")log.info("this is info log")log.warning("this is warning log")log.error("this is error log")log.critical("this is critical log")rlog=logging.getLogger("root")rlog.debug("this is debug log")rlog.info("this is info log")rlog.warning("this is warning log")rlog.error("this is error log")rlog.critical("this is critical log")

运行结果如下：

2020-08-05 00:25:02,673|DEBUG|test1.py[line:8]|this is debug log2020-08-05 00:25:02,674|INFO|test1.py[line:9]|this is info log2020-08-05 00:25:02,674|WARNING|test1.py[line:10]|this is warning log2020-08-05 00:25:02,674|ERROR|test1.py[line:11]|this is error log2020-08-05 00:25:02,674|CRITICAL|test1.py[line:12]|this is critical log2020-08-05 00:25:02,674|DEBUG|test1.py[line:15]|this is debug log2020-08-05 00:25:02,674|INFO|test1.py[line:16]|this is info log2020-08-05 00:25:02,674|WARNING|test1.py[line:17]|this is warning log2020-08-05 00:25:02,674|ERROR|test1.py[line:18]|this is error log2020-08-05 00:25:02,674|CRITICAL|test1.py[line:19]|this is

同时在test.log日志文件中生成如下日志：

2020-08-05 00:25:02,673|DEBUG|test1.py[line:8]|this is debug log2020-08-05 00:25:02,674|INFO|test1.py[line:9]|this is info log2020-08-05 00:25:02,674|WARNING|test1.py[line:10]|this is warning log2020-08-05 00:25:02,674|ERROR|test1.py[line:11]|this is error log2020-08-05 00:25:02,674|CRITICAL|test1.py[line:12]|this is

20 在上述19的基础上，加入在其他文件中想使用建好的log系统进行日志的打印，有如下两种使用方法：

import test1import logginglog=logging.getLogger("test")log.debug("this is debug log")log.info("this is info log")log.warning("this is warning log")log.error("this is error log")log.critical("this is critical log")log=test1.loggerlog.debug("this is debug log")log.info("this is info log")log.warning("this is warning log")log.error("this is error log")log.critical("this is critical log")

运行结果如下：

2020-08-05_00:31:35|DEBUG|test2.py[line:8]|this is debug log2020-08-05_00:31:35|INFO|test2.py[line:9]|this is info log2020-08-05_00:31:35|WARNING|test2.py[line:10]|this is warning log2020-08-05_00:31:35|ERROR|test2.py[line:11]|this is error log2020-08-05_00:31:35|CRITICAL|test2.py[line:12]|this is critical log2020-08-05_00:31:35|DEBUG|test2.py[line:16]|this is debug log2020-08-05_00:31:35|INFO|test2.py[line:17]|this is info log2020-08-05_00:31:35|WARNING|test2.py[line:18]|this is warning log2020-08-05_00:31:35|ERROR|test2.py[line:19]|this is error log2020-08-05_00:31:35|CRITICAL|test2.py[line:20]|this is

日志文件中也生成了对应的日志：

2020-08-05_00:31:35|DEBUG|test2.py[line:8]|this is debug log2020-08-05_00:31:35|INFO|test2.py[line:9]|this is info log2020-08-05_00:31:35|WARNING|test2.py[line:10]|this is warning log2020-08-05_00:31:35|ERROR|test2.py[line:11]|this is error log2020-08-05_00:31:35|CRITICAL|test2.py[line:12]|this is critical log2020-08-05_00:31:35|DEBUG|test2.py[line:16]|this is debug log2020-08-05_00:31:35|INFO|test2.py[line:17]|this is info log2020-08-05_00:31:35|WARNING|test2.py[line:18]|this is warning log2020-08-05_00:31:35|ERROR|test2.py[line:19]|this is error log2020-08-05_00:31:35|CRITICAL|test2.py[line:20]|this is

21 在try - except语句块中，打印异常日志可以使用log.exception(e)，这个函数可以将程序错误调用栈打印出来

import logging.configlogging.config.fileConfig("logging.conf")logger=logging.getLogger("test")log=loggertry: a=1/0except Exception as e: log.exception(e)

运行结果如下：

2020-08-05_00:35:14|ERROR|test1.py[line:12]|division by zeroTraceback (most recent call last): File "G:/lamb_source/test/log/test1.py", line 10, in a=1/0ZeroDivisionError:

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