ListItemGroup 和lazyforeach如何结合使用

@Entry 
@Component 
struct LazyForEachDemo { 
  private list: MyDataSource2 = new MyDataSource2() 
 
  @Builder 
  itemHead(text: string) { 
    Text(text) 
      .fontSize(20) 
      .backgroundColor(0xAABBCC) 
      .width("100%") 
      .padding(10) 
  } 
 
  @Builder 
  itemFoot(num: number) { 
    Text('共' + num + "节课") 
      .fontSize(16) 
      .backgroundColor(0xAABBCC) 
      .width("100%") 
      .padding(5) 
  } 
 
  aboutToAppear() { 
    for (let date = 1; date < ~~(Math.random() * 30) + 3; date++) { 
      let dayData = new dateListItem(date + "") 
      for (let index = 1; index < ~~(Math.random() * 100) + 30; index++) { 
        dayData.orderList.pushData(`hello${index}`) 
      } 
      this.list.pushData(dayData) 
    } 
  } 
 
  build() { 
    Column() { 
      List({ space: 20 }) { 
        LazyForEach(this.list, (item: dateListItem, index) => { 
          ListItemGroup({ header: this.itemHead(item.date + ""), footer: this.itemFoot(item.orderList.totalCount()) }) { 
            LazyForEach(item.orderList, (order: string, index2) => { 
              ListItem() { 
                Text(order) 
                  .onAppear(() => { 
                    console.info("appear:" + order, index2 + "") 
                  }) 
                  .width("100%") 
                  .height(60) 
                  .fontSize(20) 
                  .textAlign(TextAlign.Center) 
                  .backgroundColor(0xFFFFFF) 
              } 
            }, (item: string) => item) 
          } 
          .onAppear(() => { 
            console.info("appear:" + item, index + "") 
          }) 
          .divider({ strokeWidth: 1, color: Color.Blue }) // 每行之间的分界线 
        }) 
      } 
      .cachedCount(1) 
      .width('90%') 
      .sticky(StickyStyle.Header | StickyStyle.Footer) 
      .scrollBar(BarState.Off) 
    }.width('100%').height('100%').backgroundColor(0xDCDCDC).padding({ top: 5 }) 
  } 
} 
// Basic implementation of IDataSource to handle data listener 
class BasicDataSource implements IDataSource { 
  private listeners: DataChangeListener[] = []; 
  private originDataArray: string[] = []; 
 
  public totalCount(): number { 
    return 0; 
  } 
 
  public getData(index: number): string | dateListItem { 
    return this.originDataArray[index]; 
  } 
 
  // 该方法为框架侧调用，为LazyForEach组件向其数据源处添加listener监听 
  registerDataChangeListener(listener: DataChangeListener): void { 
    if (this.listeners.indexOf(listener) < 0) { 
      console.info('add listener'); 
      this.listeners.push(listener); 
    } 
  } 
 
  // 该方法为框架侧调用，为对应的LazyForEach组件在数据源处去除listener监听 
  unregisterDataChangeListener(listener: DataChangeListener): void { 
    const pos = this.listeners.indexOf(listener); 
    if (pos >= 0) { 
      console.info('remove listener'); 
      this.listeners.splice(pos, 1); 
    } 
  } 
 
  // 通知LazyForEach组件需要重载所有子组件 
  notifyDataReload(): void { 
    this.listeners.forEach(listener => { 
      listener.onDataReloaded(); 
    }) 
  } 
 
  // 通知LazyForEach组件需要在index对应索引处添加子组件 
  notifyDataAdd(index: number): void { 
    this.listeners.forEach(listener => { 
      listener.onDataAdd(index); 
    }) 
  } 
 
  // 通知LazyForEach组件在index对应索引处数据有变化，需要重建该子组件 
  notifyDataChange(index: number): void { 
    this.listeners.forEach(listener => { 
      listener.onDataChange(index); 
    }) 
  } 
 
  // 通知LazyForEach组件需要在index对应索引处删除该子组件 
  notifyDataDelete(index: number): void { 
    this.listeners.forEach(listener => { 
      listener.onDataDelete(index); 
    }) 
  } 
} 
// 内层数据 
class MyDataSource1 extends BasicDataSource { 
  private dataArray: string[] = []; 
 
  public totalCount(): number { 
    return this.dataArray.length; 
  } 
 
  public getData(index: number): string { 
    return this.dataArray[index]; 
  } 
 
  public addData(index: number, data: string): void { 
    this.dataArray.splice(index, 0, data); 
    this.notifyDataAdd(index); 
  } 
 
  public pushData(data: string): void { 
    this.dataArray.push(data); 
    this.notifyDataAdd(this.dataArray.length - 1); 
  } 
} 
 
// 外层数据 
class MyDataSource2 extends BasicDataSource { 
  private dataArray: dateListItem[] = []; 
 
  public totalCount(): number { 
    return this.dataArray.length; 
  } 
 
  public getData(index: number): dateListItem { 
    return this.dataArray[index]; 
  } 
 
  public addData(index: number, data: dateListItem): void { 
    this.dataArray.splice(index, 0, data); 
    this.notifyDataAdd(index); 
  } 
 
  public pushData(data: dateListItem): void { 
    this.dataArray.push(data); 
    this.notifyDataAdd(this.dataArray.length - 1); 
  } 
} 
 
class dateListItem { 
  date: string 
  orderList: MyDataSource1 
 
  constructor(date: string) { 
    this.date = date 
    this.orderList = new MyDataSource1() 
  } 
}