如何在scrapy中发送带有标头和有效负载的Post请求

import scrapy

class MySpider(scrapy.Spider):
    name = 'my_spider'
    start_urls = ['http://example.com']

    def start_requests(self):
        url = 'http://example.com/post-endpoint'
        headers = {
            'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.150 Safari/537.36',
            'Content-Type': 'application/json',
        }
        payload = {
            'key1': 'value1',
            'key2': 'value2',
        }
        yield scrapy.FormRequest(url=url, method='POST', headers=headers, formdata=payload, callback=self.parse)

    def parse(self, response):
        # 处理响应数据的方法
        pass