根据卡片状态刷新不同内容

相同的卡片可以添加到桌面上实现不同的功能，比如添加两张桌面的卡片，一张显示杭州的天气，一张显示北京的天气，设置每天早上7点触发定时刷新，卡片需要感知当前的配置是杭州还是北京，然后将对应城市的天气信息刷新到卡片上，以下示例介绍了如何根据卡片的状态动态选择需要刷新的内容。

• 卡片配置文件：配置每天早上7点触发定时刷新。

  {
    "forms": [
      {
        "name": "widget",
        "description": "This is a service widget.",
        "src": "./ets/widget/pages/WidgetCard.ets",
        "uiSyntax": "arkts",
        "window": {
          "designWidth": 720,
          "autoDesignWidth": true
        },
        "colorMode": "auto",
        "isDefault": true,
        "updateEnabled": true,
        "scheduledUpdateTime": "07:00",
        "updateDuration": 0,
        "defaultDimension": "2*2",
        "supportDimensions": ["2*2"]
      }
    ]
  }

• 卡片页面：卡片具备不同的状态选择，在不同的状态下需要刷新不同的内容，因此在状态发生变化时通过postCardAction通知EntryFormAbility。

  let storage = new LocalStorage();
  @Entry(storage)
  @Component
  struct WidgetCard {
    @LocalStorageProp('textA') textA: string = '待刷新...';
    @LocalStorageProp('textB') textB: string = '待刷新...';
    @State selectA: boolean = false;
    @State selectB: boolean = false;
  
    build() {
      Column() {
        Row() {
          Checkbox({ name: 'checkbox1', group: 'checkboxGroup' })
            .select(false)
            .onChange((value: boolean) => {
              this.selectA = value;
              postCardAction(this, {
                'action': 'message',
                'params': {
                  'selectA': JSON.stringify(value)
                }
              });
            })
          Text('状态A')
        }
  
        Row() {
          Checkbox({ name: 'checkbox2', group: 'checkboxGroup' })
            .select(false)
            .onChange((value: boolean) => {
              this.selectB = value;
              postCardAction(this, {
                'action': 'message',
                'params': {
                  'selectB': JSON.stringify(value)
                }
              });
            })
          Text('状态B')
        }
  
        Row() { // 选中状态A才会进行刷新的内容
          Text('状态A: ')
          Text(this.textA)
        }
  
        Row() { // 选中状态B才会进行刷新的内容
          Text('状态B: ')
          Text(this.textB)
        }
      }.padding('10%')
    }
  }

• EntryFormAbility：将卡片的状态存储在本地数据库中，在刷新事件回调触发时，通过formId获取当前卡片的状态，然后根据卡片的状态选择不同的刷新内容。

  import formInfo from '@ohos.app.form.formInfo'
  import formProvider from '@ohos.app.form.formProvider';
  import formBindingData from '@ohos.app.form.formBindingData';
  import FormExtensionAbility from '@ohos.app.form.FormExtensionAbility';
  import dataPreferences from '@ohos.data.preferences';
  import Want from '@ohos.app.ability.Want';
  import Base from '@ohos.base';
  
  export default class EntryFormAbility extends FormExtensionAbility {
    onAddForm(want: Want) {
      let formId: string = '';
      let isTempCard: boolean;
      if (want.parameters) {
        formId = JSON.stringify(want.parameters[formInfo.FormParam.IDENTITY_KEY]);
        isTempCard = want.parameters[formInfo.FormParam.TEMPORARY_KEY] as boolean;
        if (isTempCard === false) { // 如果为常态卡片，直接进行信息持久化
          console.info('Not temp card, init db for:' + formId);
          let promise: Promise<dataPreferences.Preferences> = dataPreferences.getPreferences(this.context, 'myStore');
          promise.then(async (storeDB: dataPreferences.Preferences) => {
            console.info("Succeeded to get preferences.");
            await storeDB.put('A' + formId, 'false');
            await storeDB.put('B' + formId, 'false');
            await storeDB.flush();
          }).catch((err: Base.BusinessError) => {
            console.info(`Failed to get preferences. ${JSON.stringify(err)}`);
          })
        }
      }
      let formData: Record<string, Object|string> = {};
      return formBindingData.createFormBindingData(formData);
    }

    onRemoveForm(formId: string) {
      console.info('onRemoveForm, formId:' + formId);
      let promise = dataPreferences.getPreferences(this.context, 'myStore');
      promise.then(async (storeDB) => {
        console.info("Succeeded to get preferences.");
        await storeDB.delete('A' + formId);
        await storeDB.delete('B' + formId);
      }).catch((err: Base.BusinessError) => {
        console.info(`Failed to get preferences. ${JSON.stringify(err)}`);
      })
    }

    // 如果在添加时为临时卡片，则建议转为常态卡片时进行信息持久化
    onCastToNormalForm(formId: string) {
      console.info('onCastToNormalForm, formId:' + formId);
      let promise: Promise<dataPreferences.Preferences> = dataPreferences.getPreferences(this.context, 'myStore');
      promise.then(async (storeDB: dataPreferences.Preferences) => {
        console.info("Succeeded to get preferences.");
        await storeDB.put('A' + formId, 'false');
        await storeDB.put('B' + formId, 'false');
        await storeDB.flush();
      }).catch((err: Base.BusinessError) => {
        console.info(`Failed to get preferences. ${JSON.stringify(err)}`);
      })
    }

    onUpdateForm(formId: string) {
      let promise: Promise<dataPreferences.Preferences> = dataPreferences.getPreferences(this.context, 'myStore');
      promise.then(async (storeDB: dataPreferences.Preferences) => {
        console.info("Succeeded to get preferences.");
        let stateA = await storeDB.get('A' + formId, 'false');
        let stateB = await storeDB.get('B' + formId, 'false');
        // A状态选中则更新textA
        if (stateA === 'true') {
          let param: Record<string, string> = { 'textA': 'AAA' };
          let formInfo: formBindingData.FormBindingData = formBindingData.createFormBindingData(param);
          await formProvider.updateForm(formId, formInfo);
        }
        // B状态选中则更新textB
        if (stateB === 'true') {
          let param: Record<string, string> = { 'textB': 'BBB' };
          let formInfo: formBindingData.FormBindingData = formBindingData.createFormBindingData(param);
          await formProvider.updateForm(formId, formInfo);
        }
        console.info(`Update form success stateA:${stateA} stateB:${stateB}.`);
      }).catch((err: Base.BusinessError) => {
        console.info(`Failed to get preferences. ${JSON.stringify(err)}`);
      })
    }

    onFormEvent(formId: string, message: string) {
      // 存放卡片状态
      console.info('onFormEvent formId:' + formId + 'msg:' + message);
      let promise: Promise<dataPreferences.Preferences> = dataPreferences.getPreferences(this.context, 'myStore');
      promise.then(async (storeDB: dataPreferences.Preferences) => {
        console.info("Succeeded to get preferences.");
        let msg: Record<string, string> = JSON.parse(message);
        if (msg.selectA != undefined) {
          console.info('onFormEvent selectA info:' + msg.selectA);
          await storeDB.put('A' + formId, msg.selectA);
        }
        if (msg.selectB != undefined) {
          console.info('onFormEvent selectB info:' + msg.selectB);
          await storeDB.put('B' + formId, msg.selectB);
        }
        await storeDB.flush();
      }).catch((err: Base.BusinessError) => {
        console.info(`Failed to get preferences. ${JSON.stringify(err)}`);
      })
    }
  };

说明：

通过本地数据库进行卡片信息的持久化时，建议先在onAddForm生命周期中通过TEMPORARY_KEY判断当前添加的卡片是否为常态卡片：如果是常态卡片，则直接进行卡片信息持久化；如果为临时卡片，则可以在卡片转为常态卡片(onCastToNormalForm)时进行持久化；同时需要在卡片销毁(onRemoveForm)时删除当前卡片存储的持久化信息，避免反复添加删除卡片导致数据库文件持续变大。

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