如何使用scrapy回调在两个爬行器之间传递参数

import scrapy

class FirstSpider(scrapy.Spider):
    name = "first"

    def start_requests(self):
        url = "http://example.com"
        yield scrapy.Request(url, callback=self.parse, meta={'param': 'value'})

    def parse(self, response):
        # 解析响应数据
        # ...

        # 创建新的Request对象，并传递参数
        url = "http://example.com/second"
        yield scrapy.Request(url, callback=self.parse_second, meta=response.meta)

    def parse_second(self, response):
        # 解析第二个爬虫的响应数据
        # ...

import scrapy

class SecondSpider(scrapy.Spider):
    name = "second"

    def start_requests(self):
        url = "http://example.com/second"
        yield scrapy.Request(url, callback=self.parse)

    def parse(self, response):
        # 获取参数
        param = response.meta.get('param')

        # 处理参数
        # ...