為什么Python記錄器無法在logging.INFO級別顯示信息或調試消息？

Question

有人可以向我解釋為什么.info（）和.debug（）調用即使看起來好像也不顯示任何內容？ 我覺得即使在通過了日志記錄模塊文檔之后，我仍然不了解一些非常基本的內容。

$  python                                    
Python 3.6.5 (default, Apr 25 2018, 14:23:58) 
[GCC 4.2.1 Compatible Apple LLVM 9.1.0 (clang-902.0.39.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import logging
>>> logger = logging.getLogger()
>>> logger.setLevel(logging.INFO)
>>> logger.warning('This is a warning. We should see it.')
This is a warning. We should see it.
>>> logger.debug('This is a debug message. We should not see it.')
>>> logger.info('This is an info message. We should... see it, right?')
>>> logger.setLevel(logging.DEBUG)
>>> logger.info('This is an info message. We should... see it, right?')
>>> logger.debug('Weird. So I guess we are not going to see this as well?')
>>> 

Answer 1

它正在記錄日志，只是不記錄到終端。 如果要查看輸出到終端的日志（類似於print ），則需要添加一個處理程序：

logger.addHandler(logging.StreamHandler())

這樣做之后，日志記錄應該按預期顯示在您的終端上。