HarmonyOS 鸿蒙Next表单提交等待时如何实现显示上层的加载动画效果

可以使用promptAction.openCustomDialog自定义弹窗实现loading效果，开始上传时打开弹窗，上传成功关闭弹窗。参考文档： https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/js-apis-promptaction-V5#promptactionopencustomdialog11

下面demo你可以参考一下：

//Index.ets
import { changeDialogBuilder, MyShowTest } from '../common/HttpUtils'
import {customDialogBuilder} from './testProm'
let myShowTest = new MyShowTest()
@Entry
@Component
struct Index {
  @State message: string = 'Hello World'
  onPageShow(): void {
    changeDialogBuilder(customDialogBuilder.bind(this))
  }
  build() {
    Row {
      Column {
        Text(this.message)
          .fontSize(50)
          .fontWeight(FontWeight.Bold)
          .onClick(() => {
            myShowTest.showTest()
          })
      }
      .width('100%')
    }
    .height('100%')
  }
}

//testProm.ets
@Builder
export function customDialogBuilder() {
  Column {
    Text('正在加载中').fontSize(16)
  }
  .height(100).width(100)
}

//HttpUtils.ets
import promptAction from '@ohos.promptAction'
let myDialogBuilder: CustomBuilder;
let customDialogId: number = 0
export function changeDialogBuilder(builder: CustomBuilder) {
  myDialogBuilder = builder
}
export class MyShowTest {
  showTest() {
    if (myDialogBuilder === undefined) {
      return
    }
    promptAction.openCustomDialog({
      builder: myDialogBuilder,
      alignment: DialogAlignment.Center,
    })
    .then((dialogId: number) => {
      customDialogId = dialogId
    })
    setTimeout(() => {
      promptAction.closeCustomDialog(customDialogId)
    }, 2000)
  }
}