WIN 10
Python 3.6.5
logging.config.dictConfig(config)
dictConfig函数位于logging.config模块，该函数通过字典参数config对logging进行配置。3.2版本新增的函数
config 字典类型，包含以下key：
* version - 表示版本，该键值为从1开始的整数。该key必选，除此之外，其它key都是可选。 * formatters - 日志格式化器，其value值为一个字典，该字典的每个键值对都代表一个Formatter，键值对中，key代表Formatter ID(自定义ID)，value为字典，描述如何配置相应的Formatter实例。默认格式为 ‘%(message)s’ * filters - 日志过滤器，其value值为一个字典，该字典的每个键值对都代表一个Filter，键值对中，key代表Filter ID(自定义ID)，value为字典，描述如何配置相应的Filter实例。 * handlers - 日志处理器，其value值为一个字典，该字典的每个键值对都代表一个Handler，键值对中，key代表Handler ID(自定义ID)，value为字典，描述如何配置相应的Handler实例，包含以下配置key： * class (必选). 日志处理器类全称 * level (可选). 指定该日志处理器需要处理哪些级别的日志，低于该级别的日志将不被该handler处理。level可以为代表日志级别的整数或者表大写字符串，字符串日志级别和数字日志级别对应关系如下：
CRITICAL = 50
FATAL = CRITICAL
ERROR = 40
WARNING = 30
WARN = WARNING
INFO = 20
DEBUG = 10
NOTSET = 0
下同，不再赘述.
* formatter (可选). 指定该日志处理器使用的日志格式化器 * filters (可选). 制定该日志处理器使用的日志过滤器
# 上述的class配置项的值，可以使用自定义Handler类，此时，如果自定义Handler类的init构造函数还需要其它参数来初始化类实例，可以继续添自定义参数，这些自定义参数被当做关键字参数会自动传递给构造函数。
一个例子：
"handlers": { "console":{ "class":"study.MyLogHandler", "formatter":"brief", "level":"INFO" }, "file": { "class": "logging.handlers.RotatingFileHandler", "formatter": "precise", "filename": "logconfig.log", "maxBytes": 1024, "backupCount": 3 } }
id为console的日志处理器被实例化为一个logging.StreamHandler，使用sys.stout作为基础实例流。id为file的日志处理器则被实例化为具有关键字参数filename ='logconfig.log'，maxBytes = 1024，backupCount = 3的 logging.handlers.RotatingFileHandler
* loggers - 日志记录器，其value值为一个字典，该字典的每个键值对都代表一个Handler，键值对中，key代表Handler ID，value为字典，描述如何配置相应的Logger实例，包含以下配置key： * level (可选). 指定该日志记录器需要记录哪些级别的日志，低于该级别的日志将不被该logger记录。 * propagate (可选). 指定该日志记录器的propagation配置，为布尔值，即True 或 False，用于控制是否向上遍历父辈日志打印器，进而控制当前日志打印器是否共享父辈打印器的日志处理器。True，向上遍历，否则不向上遍历。 * filters (可选). 指定该日志记录器使用的日志过滤器 * handlers (可选). 制定该日志记录器使用的日志处理器 * root - root logger配置。除了不支持propagate配置项以外，该配置的处理过程同处理其它logger的配置一样，配置规则也一样 * incremental - 用于判断该config配置是否解释为现有配置的增量配置，还是覆盖原有配置。默认为False，即使用现有fileConfig（）API使用的相同语义替换现有配置
study.py
study.py #!/usr/bin/env python # -*- coding:utf-8 -*- ''' @CreateTime: 2020/12/29 14:08 @Author : shouke ''' import logging import logging.config LOGGING_CONFIG = { "version": 1, "formatters": { "default": { 'format':'%(asctime)s %(filename)s %(lineno)s %(levelname)s %(message)s', }, "plain": { "format": "%(message)s", }, }, "handlers": { "console": { "class": "logging.StreamHandler", "level": "INFO", "formatter": "default", }, "console_plain": { "class": "logging.StreamHandler", "level":logging.INFO, "formatter": "plain" }, "file":{ "class": "logging.FileHandler", "level":20, "filename": "./log.txt", "formatter": "default", } }, "loggers": { "console_logger": { "handlers": ["console"], "level": "INFO", "propagate": False, }, "console_plain_logger": { "handlers": ["console_plain"], "level": "DEBUG", "propagate": False, }, "file_logger":{ "handlers": ["file"], "level": "INFO", "propagate": False, } }, "disable_existing_loggers": True, } # 运行测试 logging.config.dictConfig(LOGGING_CONFIG) logger = logging.getLogger("console_logger") logger.debug('debug message') logger.info('info message') logger.warn('warning message') logger.error('error message') logger.critical('critical message')
运行study.py，结果输出如下
2021-01-09 10:01:59,123 study.py 66 INFO info message
2021-01-09 10:01:59,123 study.py 67 WARNING warning message
2021-01-09 10:01:59,123 study.py 68 ERROR error message
2021-01-09 10:01:59,123 study.py 69 CRITICAL critical message
基于代码示例1，修改LOGGING_CONFIG及getLogger函数参数
LOGGING_CONFIG = { "version": 1, "formatters": { "default": { 'format':'%(asctime)s %(filename)s %(lineno)s %(levelname)s %(message)s', } }, "handlers": { "console": { "class": "logging.StreamHandler", "level": "INFO", "formatter": "default", } }, "disable_existing_loggers": True, "root": { "handlers": ["console"], "level": "DEBUG" }, } # 运行测试 logging.config.dictConfig(LOGGING_CONFIG) logger = logging.getLogger("root") logger.debug('debug message') logger.info('info message') logger.warn('warning message') logger.error('error message') logger.critical('critical message')
2021-01-09 10:33:03,456 study.py 38 INFO info message
2021-01-09 10:33:03,456 study.py 39 WARNING warning message
2021-01-09 10:33:03,456 study.py 40 ERROR error message
2021-01-09 10:33:03,456 study.py 41 CRITICAL critical message
Logger类，位于logging/init.py
class Logger(Filterer): #...略 def debug(self, msg, *args, **kwargs): """ Log 'msg % args' with severity 'DEBUG'. To pass exception information, use the keyword argument exc_info with a true value, e.g. logger.debug("Houston, we have a %s", "thorny problem", exc_info=1) """ if self.isEnabledFor(DEBUG): self._log(DEBUG, msg, args, **kwargs) def info(self, msg, *args, **kwargs): """ Log 'msg % args' with severity 'INFO'. To pass exception information, use the keyword argument exc_info with a true value, e.g. logger.info("Houston, we have a %s", "interesting problem", exc_info=1) """ if self.isEnabledFor(INFO): self._log(INFO, msg, args, **kwargs) #...略 def _log(self, level, msg, args, exc_info=None, extra=None, stack_info=False): """ Low-level logging routine which creates a LogRecord and then calls all the handlers of this logger to handle the record. """ sinfo = None if _srcfile: #IronPython doesn't track Python frames, so findCaller raises an #exception on some versions of IronPython. We trap it here so that #IronPython can use logging. try: fn, lno, func, sinfo = self.findCaller(stack_info) except ValueError: # pragma: no cover fn, lno, func = "(unknown file)", 0, "(unknown function)" else: # pragma: no cover fn, lno, func = "(unknown file)", 0, "(unknown function)" if exc_info: if isinstance(exc_info, BaseException): exc_info = (type(exc_info), exc_info, exc_info.__traceback__) elif not isinstance(exc_info, tuple): exc_info = sys.exc_info() record = self.makeRecord(self.name, level, fn, lno, msg, args, exc_info, func, extra, sinfo) self.handle(record) def handle(self, record): """ Call the handlers for the specified record. This method is used for unpickled records received from a socket, as well as those created locally. Logger-level filtering is applied. """ if (not self.disabled) and self.filter(record): self.callHandlers(record) def hasHandlers(self): """ See if this logger has any handlers configured. Loop through all handlers for this logger and its parents in the logger hierarchy. Return True if a handler was found, else False. Stop searching up the hierarchy whenever a logger with the "propagate" attribute set to zero is found - that will be the last logger which is checked for the existence of handlers. """ c = self rv = False while c: if c.handlers: rv = True break if not c.propagate: break else: c = c.parent return rv def callHandlers(self, record): """ Pass a record to all relevant handlers. Loop through all handlers for this logger and its parents in the logger hierarchy. If no handler was found, output a one-off error message to sys.stderr. Stop searching up the hierarchy whenever a logger with the "propagate" attribute set to zero is found - that will be the last logger whose handlers are called. """ c = self found = 0 while c: for hdlr in c.handlers: found = found + 1 if record.levelno >= hdlr.level: hdlr.handle(record) if not c.propagate: c = None #break out else: c = c.parent if (found == 0): if lastResort: if record.levelno >= lastResort.level: lastResort.handle(record) elif raiseExceptions and not self.manager.emittedNoHandlerWarning: sys.stderr.write("No handlers could be found for logger" " \"%s\"\n" % self.name) self.manager.emittedNoHandlerWarning = True
默认的，当通过logger.debug，logger.info的方式打印日志时，会先判断对应日志级别是否开启，如果开启，则调用logger实例的_log方法，接着经过一连串的函数调用（self._log() -> self.handle -> self.callHandlers），如上，self.callHandlers中，会先遍历当前日志打印器自身的所有日志处理器，处理日志消息，然后判断propagate属性是否为True，如果为True，则获取上级日志打印器，继续遍历其日志处理器，处理消息，否则不遍历上级
另外，查看hasHandlers函数可知，判断一个logger是否有日志处理器，也用到了propagate，如果propagate为True，则遍历父级日志打印器，看其是否存在日志处理器，如果父级或者父辈日志打印器存在日志处理器，则判断该logger拥有日志处理器。
由此可见，propagate功能就是用于控制是否向上遍历父辈日志打印器，进而控制当前日志打印器是否共享父辈打印器的日志处理器。
Python 日志打印之logging.config.dictConfig使用总结介绍到这里，更多Python学习请参考编程字典Python教程 和问答部分，谢谢大家对编程字典的支持。
原文链接：https://www.cnblogs.com/shouke/p/14256086.html
