HarmonyOS http post请求参数传递

关于 extraData 额外参数 可以参考以下链接：

https://developer.huawei.com/consumer/cn/doc/harmonyos-references/js-apis-http-0000001774121990#ZH-CN_TOPIC_0000001811318566__httprequestoptions

建议使用 ‘content-Type’为’application/json’，该字段对应的类型通常为Object，extraData字段直接传入param

class Param {
  a:string = ''
}
async httpTest(){
  let options: http.HttpRequestOptions = {
    method: http.RequestMethod.POST,
    readTimeout: 5000,
    header: new Object({'content-Type': 'application/json'}),
    connectTimeout: 5000,
    extraData: new Param()
  }

  let response = await http.createHttp().request('',options)
}