如何使用Scrapy获取stat (item_scraped_count)？

from scrapy import signals

class MySpider(scrapy.Spider):
    name = 'my_spider'

    def __init__(self, *args, **kwargs):
        super(MySpider, self).__init__(*args, **kwargs)
        self.item_count = 0

    @classmethod
    def from_crawler(cls, crawler, *args, **kwargs):
        spider = super(MySpider, cls).from_crawler(crawler, *args, **kwargs)
        crawler.signals.connect(spider.spider_closed, signal=signals.spider_closed)
        return spider

    def parse(self, response):
        # 爬取数据的逻辑处理
        self.item_count += 1

    def spider_closed(self, spider):
        item_scraped_count = spider.crawler.stats.get_value('item_scraped_count')
        self.logger.info("Total items scraped: %s" % item_scraped_count)