HarmonyOS ListItemGroup和LazyForEach如何结合

@Entry 
@Component 
struct ListItemGroupExample { 
  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 }) 
  } 
}