scrapy开启时或者关闭时的勾子

在spider class中

def closed(self,reason):

当spider关闭的时候，执行此函数。

spider_opened(self,reason)

spider_closed(reason)

在pipeline中

open_spider(self, spider)

This method is called when the spider is opened.

close_spider(self, spider)

This method is called when the spider is closed.