1. 程式人生 > >python中文件變化監控-watchdog

python中文件變化監控-watchdog

col 註釋 變量 改變 mac rup tro func .com

在python中文件監控主要有兩個庫,一個是pyinotify ( https://github.com/seb-m/pyinotify/wiki ),一個是watchdog(http://pythonhosted.org/watchdog/)。pyinotify依賴於Linux平臺的inotify,後者則對不同平臺的的事件都進行了封裝。因為我主要用於Windows平臺,所以下面著重介紹watchdog(推薦大家閱讀一下watchdog實現源碼,有利於深刻的理解其中的原理)。
watchdog在不同的平臺使用不同的方法進行文件檢測。在init.py中發現了如下註釋:

|Inotify|                             Linux 2.6.13+                    ``inotify(7)`` based observer
|FSEvents|                            Mac OS X                         FSEvents based observer
|Kqueue|                              Mac OS X and BSD with kqueue(2)  ``kqueue(2)`` based observer
|WinApi|(ReadDirectoryChangesW)       MS Windows                       Windows API-based observer
|Polling|                             Any                              fallback implementation

給出示例代碼如下:

from watchdog.observers import Observer
from watchdog.events import *
import time

class FileEventHandler(FileSystemEventHandler):
    def __init__(self):
        FileSystemEventHandler.__init__(self)

    def on_moved(self, event):
        if event.is_directory:
            print("directory moved from {0} to {1}".format(event.src_path,event.dest_path))
        else:
            print("file moved from {0} to {1}".format(event.src_path,event.dest_path))

    def on_created(self, event):
        if event.is_directory:
            print("directory created:{0}".format(event.src_path))
        else:
            print("file created:{0}".format(event.src_path))

    def on_deleted(self, event):
        if event.is_directory:
            print("directory deleted:{0}".format(event.src_path))
        else:
            print("file deleted:{0}".format(event.src_path))

    def on_modified(self, event):
        if event.is_directory:
            print("directory modified:{0}".format(event.src_path))
        else:
            print("file modified:{0}".format(event.src_path))

if __name__ == "__main__":
    observer = Observer()
    event_handler = FileEventHandler()
    observer.schedule(event_handler,"d:/dcm",True)
    observer.start()
    try:
        while True:
            time.sleep(1)
    except KeyboardInterrupt:
        observer.stop()
    observer.join()

watchdog主要采用觀察者模型(廢話,從變量命名就可以看出來)。主要有三個角色:observer,event_handler,被監控的文件夾。三者原本是獨立的,主要通過observer.schedule函數將三者串起來,意思為observer不斷檢測調用平臺依賴代碼對監控文件夾進行變動檢測,當發現改變時,通知event_handler處理。最後特別推薦讀者有時間可以閱讀一下watchdog的源碼,寫的易懂而且架構很好。

python中文件變化監控-watchdog