HarmonyOS 鸿蒙Next中用 '@ohos.request' 去上传一个 50M 的视频, 注册了 'progress' 进度监听. 但该回调只在上传完成后调用一次. 不应该是多次回调吗?

参考一下下面的代码：

import http from '@ohos.net.http';
import util from '@ohos.util';
import fs from '@ohos.file.fs';
import picker from '@ohos.file.picker';
import systemDateTime from '@ohos.systemDateTime';
import request from '@ohos.request';

@Entry
@Component
struct Index {
  //连接、通讯历史记录
  @State msgHistory: string = ''
  //上传地址
  @State uploadUrl: string = "http://192.168.100.100:8081/upload"
  //要上传的文件
  @State uploadFilePath: string = ""
  //是否允许上传
  @State canUpload: boolean = false
  scroller: Scroller = new Scroller()

  build() {
    Row() {
      Column() {
        Text("request上传示例")
          .fontSize(14)
          .fontWeight(FontWeight.Bold)
          .width('100%')
          .textAlign(TextAlign.Center)
          .padding(10)

        Flex({ justifyContent: FlexAlign.Start, alignItems: ItemAlign.Center }) {
          Text("上传的文件：")
            .fontSize(14)
            .width(100)
            .flexGrow(0)

          TextInput({ text: this.uploadFilePath })
            .enabled(false)
            .width(100)
            .fontSize(11)
            .flexGrow(1)

          Button("选择")
            .onClick(() => {
              this.selectFile()
            })
            .width(70)
            .fontSize(14)
        }
        .width('100%')
        .padding(10)

        Flex({ justifyContent: FlexAlign.Start, alignItems: ItemAlign.Center }) {
          Text("上传地址：")
            .fontSize(14)
            .width(80)
            .flexGrow(0)

          TextInput({ text: this.uploadUrl })
            .onChange((value) => {
              this.uploadUrl = value
            })
            .width(110)
            .fontSize(11)
            .flexGrow(1)

          Button("请求")
            .onClick(() => {
              this.uploadFile()
            })
            .enabled(this.canUpload)
            .width(70)
            .fontSize(14)
            .flexGrow(0)
        }
        .width('100%')
        .padding(10)

        Scroll(this.scroller) {
          Text(this.msgHistory)
            .textAlign(TextAlign.Start)
            .padding(10)
            .width('100%')
            .backgroundColor(0xeeeeee)
        }
        .align(Alignment.Top)
        .backgroundColor(0xeeeeee)
        .height(300)
        .flexGrow(1)
        .scrollable(ScrollDirection.Vertical)
        .scrollBar(BarState.On)
        .scrollBarWidth(20)
      }
      .width('100%')
      .justifyContent(FlexAlign.Start)
      .height('100%')
    }
    .height('100%')
  }

  //上传文件
  async uploadFile() {
    let context = getContext(this)
    let segments = this.uploadFilePath.split('/')
    //文件名称
    let fileName = segments[segments.length-1]

    //计划复制到的目标路径
    let realUri = context.cacheDir + "/" + fileName

    //复制选择的文件到沙箱cache文件夹
    try {
      let file = await fs.open(this.uploadFilePath);
      fs.copyFileSync(file.fd, realUri)
    } catch (err) {
      this.msgHistory += 'err.code : ' + err.code + ', err.message : ' + err.message;
    }

    let uploadTask: request.UploadTask
    let uploadConfig: request.UploadConfig = {
      url: this.uploadUrl,
      header: { 'Accept': '*/*' },
      method: "POST",
      files: [{ filename: fileName, name: fileName, uri: `internal://cache/${fileName}`, type: "txt" }],
      data: [],
    };

    try {
      request.uploadFile(context, uploadConfig).then((data) => {
        uploadTask = data;
        uploadTask.on("progress", (size, tot) => {
          this.msgHistory += `上传进度：${size}/${tot}\r\n`
        })
        uploadTask.on("complete", () => {
          this.msgHistory += "上传完成\r\n"
        })
      }).catch((e) => {
        this.msgHistory += "请求失败：" + e.message + "\r\n"
      })
    } catch (err) {
      this.msgHistory += 'err.code : ' + err.code + ', err.message : ' + err.message;
    }
  }

  //选择文件，为简单起见，选择一个不太大的文本文件
  selectFile() {
    let documentPicker = new picker.DocumentViewPicker();
    documentPicker.select().then((result) => {
      if (result.length > 0) {
        this.uploadFilePath = result[0]
        this.msgHistory += "select file: " + this.uploadFilePath + "\r\n";
        this.canUpload = true
      }
    }).catch((e) => {
      this.msgHistory += 'DocumentViewPicker.select failed ' + e.message + "\r\n";
    });
  }
}