HarmonyOS自定义弹窗只能写在组件里面，不能写在方法里面吗？

import { GlobalContext } from './GlobalContext' 
import { testPromptDialog } from './HttpUtil' 
 
 
@Entry 
@Component 
struct Index { 
  @State message: string = 'Hello World' 
 
  aboutToAppear(): void { 
    GlobalContext.getContext().setObject('UIContext', this) 
  } 
 
  build() { 
    Row() { 
      Column() { 
        Text(this.message) 
          .fontSize(50) 
          .fontWeight(FontWeight.Bold) 
          .onClick(() => { 
            testPromptDialog() 
          }) 
      } 
      .width('100%') 
    } 
    .height('100%') 
 
    .backgroundColor(Color.Orange) 
  } 
}

export class GlobalContext { 
  private constructor() { 
  } 
 
  private static instance: GlobalContext; 
  private _objects = new Map<string, Object>(); 
 
  public static getContext(): GlobalContext { 
    if (!GlobalContext.instance) { 
      GlobalContext.instance = new GlobalContext(); 
    } 
    return GlobalContext.instance; 
  } 
 
  getObject(value: string): Object | undefined { 
    return this._objects.get(value); 
  } 
 
  setObject(key: string, objectClass: Object): void { 
    this._objects.set(key, objectClass); 
  } 
}

import { promptAction } from '@kit.ArkUI'; 
import { GlobalContext } from './GlobalContext'; 
 
 
let customDialogId: number = 0 
 
 
@Builder 
export function customDialogBuilder(content: String) { 
  Column() { 
    Text(`Tip: ${content} `).fontSize(20).height("30%") 
    Text('失败原因：!!!!').fontSize(16).height("30%") 
    Row() { 
      Button("确认").onClick(() => { 
        promptAction.closeCustomDialog(customDialogId) 
      }) 
      Blank().width(50) 
      Button("取消").onClick(() => { 
        promptAction.closeCustomDialog(customDialogId) 
      }) 
    } 
    .margin({top: 30}) 
  }.height(200).padding(5) 
} 
 
export function testPromptDialog() { 
 
  const that = GlobalContext.getContext().getObject('UIContext') as UIContext; 
  if (that) { 
    promptAction.openCustomDialog({ 
      builder: customDialogBuilder.bind(that, "网络请求失败！") 
    }).then((dialogId: number) => { 
      customDialogId = dialogId; 
    }) 
  } 
}