


Python logging module knowledge points revealed: common questions all in one place
Mar 08, 2024 am 08:00 AMpython logging module basics
The basic principle of the logging module is to create a logger (logger) and then record messages by calling the logger method. A logger has a level that determines which messages will be logged. The logging module defines several predefined levels, including DEBUG, INFO, WARNING, ERROR, and CRITICAL.
import logging # 創(chuàng)建一個(gè)名為 "my_logger" 的記錄器,并設(shè)置其級(jí)別為 INFO logger = logging.getLogger("my_logger") logger.setLevel(logging.INFO)
A logger can log messages through its methods:
# 記錄一條 INFO 級(jí)別的消息 logger.info("This is an INFO message") # 記錄一條 WARNING 級(jí)別的消息 logger.warning("This is a WARNING message") # 記錄一條 ERROR 級(jí)別的消息 logger.error("This is an ERROR message")
LogHandler
The log handler (handler) writes log messages to a specific destination, such as the console, file, or Networkserver. The logging module provides several predefined handlers:
# 創(chuàng)建一個(gè)控制臺(tái)處理程序 handler = logging.StreamHandler() # 創(chuàng)建一個(gè)文件處理程序,將日志寫入文件 "my_log.txt" handler = logging.FileHandler("my_log.txt")
Handlers can be attached to the logger by adding to the logger:
# 將處理程序添加到記錄器 logger.addHandler(handler)
Log formatter
The log formatter (fORMatter) controls the appearance of log messages. The logging module provides several predefined formatters:
# 創(chuàng)建一個(gè)基本格式器 formatter = logging.BasicFormatter() # 使用自定義格式字符串創(chuàng)建自定義格式器 formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
Formatters can be attached to handlers by adding to the handler:
# 將格式器添加到處理程序 handler.setFormatter(formatter)
common problem
1. How to set logging level in Python script?
import logging # 設(shè)置根日志記錄器的級(jí)別為 INFO logging.basicConfig(level=logging.INFO)
2. How to log exceptions?
try: # 嘗試執(zhí)行一些代碼 except Exception as e: # 記錄異常 logger.error(e, exc_info=True)
3. How to disable a specific handler?
# 禁用控制臺(tái)處理程序 logger.removeHandler(handler)
4. How to use custom log format?
# 使用自定義格式字符串創(chuàng)建自定義格式器 formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s") # 將格式器添加到處理程序 handler.setFormatter(formatter)
5. How to catch uncaught exceptions and log them to a file?
import sys import logging def exception_handler(type, value, traceback): # 記錄未捕獲的異常 logger.error(value, exc_info=(type, value, traceback)) sys.excepthook = exception_handler
in conclusion
Python The logging module is a powerful tool that can help you easily log and process application messages. By mastering its key points, you can effectively use the logging module to debug, troubleshoot, and analyze the behavior of your application.
The above is the detailed content of Python logging module knowledge points revealed: common questions all in one place. For more information, please follow other related articles on the PHP Chinese website!

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