HarmonyOS 关于下载文件采用POST请求方式

可以使用RemoteCommunicationKit中的post请求和downloadToFile来实现，文档参考：

https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/remote-communication-rcp-V5

可使用rcp能力实现文件下载，onDownloadProgress可返回当前下载进度，参考地址：

https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/remote-communication-rcp-V5#section557714186379

可以使用rcp的TracingConfiguration里的httpEventsHandler来实现文件下载参考地址：

https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/remote-communication-rcp-V5#section557714186379

示例参考：

import { BusinessError } from '@kit.BasicServicesKit';
import { rcp } from '@kit.RemoteCommunicationKit';

// 自定义响应处理器
const customHttpEventsHandler: rcp.HttpEventsHandler = {
  // 处理文件字节流的逻辑
  onDataReceive: (incomingData: ArrayBuffer) => {
    console.log("Received data:", incomingData);
    return incomingData.byteLength;
  },
};
//Configure tracing settings 
const tracingConfig: rcp.TracingConfiguration = { httpEventsHandler: customHttpEventsHandler, };
const session = rcp.createSession({ requestConfiguration: { tracing: tracingConfig } });
let req = new rcp.Request("http://huawei.com", "POST");
session.fetch(req).then((response) => {
  console.log(JSON.stringify(response));
  session.close();
}).catch((err: BusinessError) => {
  console.error("err:" + JSON.stringify(err));
  session.close();
})