. Its main advantages are as follows:
- 1. You can set different log levels to output only important information in the release version without displaying a large number of debugging information;
- 2. Especially when the code runs on the server, when there is a problem, it can be analyzed by viewing the log.
Basic use of logging module:
- Set logger name
logger = logging.getLogger(log_name)
- Set log level
logger.setLevel(logging.info)
- Create a handler to write to the log file
fh = logging.FileHandler(log_file)
- Set the log level, which is logging.WARNING by default
fh.setLevel(logLevel[log_level])
- Define the output format of handler
formatter = logging.Formatter('%(asctime)s %(name)s [line:%(lineno)d] %(levelname)s %(message)s')
fh.setFormatter(formatter)
- Add handler
logger.addHandler(fh)
- format
%(levelno)s: print log level values
%(levelname)s: print log level name
%(pathname)s: print the path of the current executing program, which is actually sys.argv[0]
%(filename)s: print the current executing program name
%(funcName)s: current function for printing logs
%(lineno)d: print the current line number of the log
%(ASCII) s: time to print log
%(thread)d: print thread ID
%(threadName)s: print thread name
%(process)d: print process ID
%(message)s: print log information
The example code is as follows:
import logging
import datetime
import os
# Define log level dictionary
logLevelDic={
"info":logging.INFO,
"debug":logging.DEBUG,
"warning":logging.WARNING,
"error":logging.ERROR
}
# Log save path
logSavePath=os.path.join(os.getcwd(),"logs")
if not os.path.exists(logSavePath):
os.makedirs(logSavePath,exist_ok=True)
# current time
curTime=datetime.datetime.now().strftime("%Y%m%d")
# Full name of the saved log
logFile=os.path.join(logSavePath,curTime+".SADCI.log")
# log level
logLevel="error"
class Logger:
def __init__(self,logFile=logFile,logLevel=logLevelDic["error"]):
self.logFile=logFile
self.logLevel=logLevel
# Set logger name
self.logger=logging.getLogger()
# Set parameter level
self.logger.setLevel(self.logLevel)
self.formatter=logging.Formatter("%(asctime)s - %(filename)s[line:%(lineno)d] - %(levelname)s: %(message)s")
# Determine whether handlers exist
if not self.logger.handlers:
# Write to console
consoleStream=logging.StreamHandler()
consoleStream.setLevel(self.logLevel)
consoleStream.setFormatter(self.formatter)
# write file
fileStream=logging.FileHandler(self.logFile,mode="a")
fileStream.setLevel(self.logLevel)
fileStream.setFormatter(self.formatter)
self.logger.addHandler(consoleStream)
self.logger.addHandler(fileStream)
def MyLogger():
return Logger(logFile=logFile,logLevel=logLevelDic[logLevel]).logger
if __name__ == '__main__':
MyLogger().error("test logg")