如何编写自定义python日志处理程序？

Question

如何编写自定义控制台日志功能,仅在控制台窗口上输出日志消息在一行(不附加),直到第一个常规日志记录.

progress = ProgressConsoleHandler()
console  = logging.StreamHandler()  

logger = logging.getLogger('test')
logger.setLevel(logging.DEBUG) 
logger.addHandler(console)  
logger.addHandler(progress)

logger.info('test1')
for i in range(3):
    logger.progress('remaining %d seconds' % i)
    time.sleep(1)   
logger.info('test2')

这样控制台输出只有三行:

INFO: test1
remaining 0 seconds... 
INFO: test2

关于如何实现这个的最佳方法的任何建议？

Answer 1

import logging
class ProgressConsoleHandler(logging.StreamHandler):
    """
    A handler class which allows the cursor to stay on
    one line for selected messages
    """
    on_same_line = False
    def emit(self, record):
        try:
            msg = self.format(record)
            stream = self.stream
            same_line = hasattr(record, 'same_line')
            if self.on_same_line and not same_line:
                stream.write(self.terminator)
            stream.write(msg)
            if same_line:
                stream.write('... ')
                self.on_same_line = True
            else:
                stream.write(self.terminator)
                self.on_same_line = False
            self.flush()
        except (KeyboardInterrupt, SystemExit):
            raise
        except:
            self.handleError(record)
if __name__ == '__main__':
    import time
    progress = ProgressConsoleHandler()
    console  = logging.StreamHandler()  

    logger = logging.getLogger('test')
    logger.setLevel(logging.DEBUG) 
    logger.addHandler(progress)

    logger.info('test1')
    for i in range(3):
        logger.info('remaining %d seconds', i, extra={'same_line':True})
        time.sleep(1)   
    logger.info('test2')

请注意,只有一个处理程序正在注册,并且extra让处理程序知道它的关键字参数应该保持在一行上.该emit()方法中有更多逻辑来处理应保留在一行上的消息与需要拥有自己的行的消息之间的更改.