Web组件如何实现文件上传功能？

import web_webview from '@ohos.web.webview';
import picker from '@ohos.file.picker';
import { BusinessError } from '@ohos.base';
@Entry
@Component
struct Index {
  controller: web_webview.WebviewController = new web_webview.WebviewController()
  build() {
    Column() {
      Web({ src: $rawfile('xxx.html'), controller: this.controller })
        .onShowFileSelector((event) => {
          // 点击上传按钮后会回调此方法
          const documentSelectOptions = new picker.DocumentSelectOptions();
          let uri: string | null = null;
          const documentViewPicker = new picker.DocumentViewPicker();
          documentViewPicker.select(documentSelectOptions).then((documentSelectResult) => {
            uri = documentSelectResult[0];
            if (event) {
              event.result.handleFileList([uri]);
            }
          }).catch((err: BusinessError) => {
            console.error(`Invoke documentViewPicker.select failed, code is ${err.code}, message is ${err.message}`);
          })
          return true
        })
    }
    .width('100%')
    .height('100%')
    .justifyContent(FlexAlign.Center)
  }
}