scrapy-redis如何将第一个请求实现为post请求

from scrapy_redis.spiders import RedisSpider
from scrapy.http import Request, FormRequest

class MySpider(RedisSpider):
    name = 'my_spider'
    redis_key = 'my_spider:start_urls'

    def start_requests(self):
        # 构造POST请求的参数
        formdata = {
            'param1': 'value1',
            'param2': 'value2',
        }
        # 发送POST请求
        yield FormRequest(url='http://example.com/post_url', formdata=formdata, callback=self.parse)

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

SCHEDULER = "scrapy_redis.scheduler.Scheduler"
DUPEFILTER_CLASS = "scrapy_redis.dupefilter.RFPDupeFilter"