要调用该方法，您需要使用 self. 限定函数.除此之外，如果您想传递文件名，请添加 filename 参数(或您想要的其他名称).

To call the method, you need to qualify function with self.. In addition to that, if you want to pass a filename, add a filename parameter (or other name you want).

class MyHandler(FileSystemEventHandler):

    def on_any_event(self, event):
        srcpath = event.src_path
        print (srcpath, 'has been ',event.event_type)
        print (datetime.datetime.now())
        filename = srcpath[12:]
        self.dropbox_fn(filename) # <----

    def dropbox_fn(self, filename):  # <-----
        print('In dropbox_fn:', filename)