HarmonyOS 聊天窗口，历史消息如何基于底部展示？

// xxx.ets  
@Entry  
@Component  
struct RefreshExample {  
  @State isRefreshing: boolean = false  
  @State arr: String[] = ['0', '1', '2', '3', '4','5','6','7','8','9','10']  
  listScroller: ListScroller = new ListScroller()  
  build() {  
    Column() {  
      Refresh({ refreshing: $$this.isRefreshing}) {  
        List({scroller: this.listScroller}) {  
          ForEach(this.arr, (item: string) => {  
            ListItem() {  
              Text('' + item)  
                .width('100%').height(100).fontSize(16)  
                .textAlign(TextAlign.Center).borderRadius(10).backgroundColor(0xFFFFFF)  
            }  
          }, (item: string) => item)  
        }  
        .onScrollIndex((first: number) => {  
          console.info(first.toString())  
        })  
        .width('100%')  
        .height('100%')  
        .divider({strokeWidth:1,color:Color.Yellow,startMargin:10,endMargin:10})  
        .scrollBar(BarState.Off)  
      }  
      .onAppear(() => {  
        this.listScroller.scrollToIndex(  
          this.arr.length - 1,  
          false, //默认  
        )  
      })  
      .onStateChange((refreshStatus: RefreshStatus) => {  
        console.info('Refresh onStatueChange state is ' + refreshStatus)  
      })  
      .onRefreshing(() => {  
        setTimeout(() => {  
          this.isRefreshing = false  
        }, 2000)  
        console.log('onRefreshing test')  
      })  
      .backgroundColor(0x89CFF0)  
    }  
  }  
}
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List({  
        initialIndex: this.arr.length - 1,  
        scroller: this.listScroller  
      })
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