请求服务器图片资源刷新卡片

downloadFile(context: BaseContext, config: DownloadConfig): Promise
updateForm(formId: string, formBindingData: formBindingData.FormBindingData): Promise
postCardAction(component: Object, action: Object): void

//pages/WidgetCard.ets 
let storage = new LocalStorage(); 
@Entry(storage) 
@Component 
struct WidgetCard { 
  @LocalStorageProp('text') text: string = '加载中...'; 
  @LocalStorageProp('loaded') loaded: boolean = false; 
  @LocalStorageProp('imgName') imgName: string = 'name'; 
 
  build() { 
    Column() { 
      Text(this.text) 
        .fontSize('12vp') 
        .textAlign(TextAlign.Center) 
        .width('100%') 
        .height('30%') 
        .margin({bottom:20}) 
      Row() { 
        if (this.loaded) { 
          Image('memory://' + this.imgName) 
            .width('30%') 
            .height('30%') 
            .margin('5%') 
        } else { 
          Image($r("app.media.startIcon")) 
            .width('20%') 
            .height('20%') 
            .margin('5%') 
        } 
      }.alignItems(VerticalAlign.Center) 
      .justifyContent(FlexAlign.Center) 
      Button('刷新') 
        .height('15%') 
        .onClick(() => { 
          //发送message，触发卡片的onFormEvent生命周期 
          postCardAction(this, { 
            'action': 'message', 
            'params': { 
              'info': 'refreshImage' 
            } 
          }); 
        }) 
    } 
    .width('100%').height('100%') 
    .alignItems(HorizontalAlign.Center) 
    .padding('5%') 
  } 
}
//entryformability/EntryFormAbility 
import formBindingData from '@ohos.app.form.formBindingData'; 
import formProvider from '@ohos.app.form.formProvider'; 
import FormExtensionAbility from '@ohos.app.form.FormExtensionAbility'; 
import request from '@ohos.request'; 
import fs from '@ohos.file.fs'; 
import Base from '@ohos.base'; 
import fileFs from '@ohos.file.fs'; 
import Want from '@ohos.app.ability.Want'; 
import formInfo from '@ohos.app.form.formInfo'; 
 
export default class EntryFormAbility extends FormExtensionAbility { 
  onAddForm(want: Want) { 
    // 假设在当前卡片应用的tmp目录下有一个本地图片：head.PNG 
    let tempDir = this.context.getApplicationContext().tempDir; 
    // 打开本地图片并获取其打开后的fd 
    let file: fileFs.File; 
    let imgBear: Record<string, number>; 
    try { 
      file = fs.openSync(tempDir + '/' + 'icon.png'); 
      imgBear = { 
        'imgBear': file.fd 
      } 
    } catch (e) { 
      console.error(`openSync failed: ${JSON.stringify(e as Base.BusinessError)}`); 
    } 
    class FormDataClass{ 
      text: string = 'Image: Bear' 
      imgName: string = 'imgBear' 
      loaded: boolean = true 
      formImages: Record<string, number> = imgBear 
    } 
    let formData = new FormDataClass(); 
 
    // 将fd封装在formData中并返回至卡片页面 
    return formBindingData.createFormBindingData(formData); 
  } 
 
  onCastToNormalForm(formId: string) { 
    // Called when the form provider is notified that a temporary form is successfully 
    // converted to a normal form. 
  } 
 
  onUpdateForm(formId: string) { 
    // Called to notify the form provider to update a specified form. 
  } 
 
  onChangeFormVisibility(newStatus: Record<string, number>) { 
    // Called when the form provider receives form events from the system. 
  } 
 
  onFormEvent(formId: string, message: string) { 
    let param: Record<string, string> = { 
      'text': '刷新中...' 
    }; 
    let formInfo: formBindingData.FormBindingData =formBindingData.createFormBindingData(param); 
    formProvider.updateForm(formId, formInfo); 
    // 注意：FormExtensionAbility在触发生命周期回调时被拉起，仅能在后台存在5秒 
    // 建议下载能快速下载完成的小文件，如在5秒内未下载完成，则此次网络图片无法刷新至卡片页面上 
    let netFile = 'https://piccpndali.v.myalicdn.com/pic/cctv2_2.png'; // 需要在此处使用真实的网络图片下载链接 
    let tempDir = this.context.getApplicationContext().tempDir; 
    let fileName = 'file' + Date.now(); 
    let tmpFile = tempDir + '/' + fileName+'.png'; 
    console.info('ArkTSCard download complete:'); 
    request.downloadFile(this.context, { 
      url: netFile, filePath: tmpFile, enableMetered: true, enableRoaming: true 
    }).then((task) => { 
      task.on('complete', () => { 
        console.info('ArkTSCard download complete:' + tmpFile); 
        let file: fileFs.File; 
        let imgBear: Record<string, number>; 
        try { 
          file = fs.openSync(tmpFile); 
          imgBear = { 
            'imgBear': file.fd 
          } 
          console.info('ArkTSCard download file.fd:' + file.fd); 
        } catch (e) { 
          console.error(`openSync failed: ${JSON.stringify(e as Base.BusinessError)}`); 
        } 
        class FormDataClass{ 
          text: string = 'Image:' + fileName 
          imgName: string = 'imgBear' 
          loaded: boolean = true 
          formImages: Record<string, number> = imgBear 
        } 
        let formData = new FormDataClass(); 
        console.info('FormAbility updateForm datainfo:{'+formData.loaded+' '+ formData.text + ' ' +formData.formImages +' ' +formData.imgName +'}.'); 
        let formInfo = formBindingData.createFormBindingData(formData); 
        formProvider.updateForm(formId, formInfo).then(() => { 
          console.info('FormAbility updateForm success.'); 
        }).catch((error: Base.BusinessError) => { 
          console.error('FormAbility updateForm failed: ' + JSON.stringify(error)); 
        }); 
      }) 
      task.on('fail', (err: number) => { 
        console.info('ArkTSCard download task failed. Cause:' + err); 
        let param: Record<string, string> = { 
          'text': '刷新失败' 
        }; 
        let formInfo: formBindingData.FormBindingData = formBindingData.createFormBindingData(param); 
        formProvider.updateForm(formId, formInfo); 
      }); 
    }).catch((err: Base.BusinessError) => { 
      console.error('Failed to request the download. Cause: ' + JSON.stringify(err)); 
    }); 
  } 
 
  onRemoveForm(formId: string) { 
    // Called to notify the form provider that a specified form has been destroyed. 
  } 
 
  onAcquireFormState(want: Want) { 
    // Called to return a {@link FormState} object. 
    return formInfo.FormState.READY; 
  } 
};