HarmonyOS 多层json购物车类型结构应该如何使用懒加载

如下示例代码，重新定义数据源数据类型，通过配合HashMap实现嵌套懒加载效果。

import HashMap from '@ohos.util.HashMap';
class BasicDataSource implements IDataSource {
  private listeners: DataChangeListener[] = [];
  private originDataArray: Array<TimeTable> | Array<string> = [];
  public totalCount(): number {
    return 0;
  }
  public getData(index: number): TimeTable | string {
    return this.originDataArray[index];
  }
  registerDataChangeListener(listener: DataChangeListener): void {
    if (this.listeners.indexOf(listener) < 0) {
      console.info('add listener');
      this.listeners.push(listener);
    }
  }
  unregisterDataChangeListener(listener: DataChangeListener): void {
    const pos = this.listeners.indexOf(listener);
    if (pos >= 0) {
      console.info('remove listener');
      this.listeners.splice(pos, 1);
    }
  }
  notifyDataReload(): void {
    this.listeners.forEach(listener => {
      listener.onDataReloaded();
    })
  }
  notifyDataAdd(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataAdd(index);
      // 写法2：listener.onDatasetChange({type: DataOperationType.ADD, index: index});
    })
  }
  notifyDataChange(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataChange(index);
    })
  }
  notifyDataDelete(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataDelete(index);
    })
  }
  notifyDataMove(from: number, to: number): void {
    this.listeners.forEach(listener => {
      listener.onDataMove(from, to);
    })
  }
}
class MyDataSource extends BasicDataSource {
  private dataArray: TimeTable[] | Array<string> = []
  constructor(Datas: Array<TimeTable> | Array<string>) {
    super()
    this.dataArray = Datas
  }
  public totalCount(): number {
    return this.dataArray.length;
  }
  public getData(index: number): TimeTable | string {
    return this.dataArray[index];
  }
  public addDataTimeTable(index: number, data: TimeTable ): void {
    this.dataArray.splice(index, 0, data);
    this.notifyDataAdd(index);
  }
  public addDataString(index: number, data: string): void {
    this.dataArray.splice(index, 0, data);
    this.notifyDataAdd(index);
  }
  public pushDataTimeTable(data: TimeTable): void {
    (this.dataArray as Array<TimeTable>).push(data);
    this.notifyDataAdd(this.dataArray.length - 1);
  }
  public pushDataString(data: string): void {
    (this.dataArray as Array<string>).push(data);
    this.notifyDataAdd(this.dataArray.length - 1);
  }
}
interface TimeTable {
  title: string;
  projects: string[];
}
@Entry
@Component
struct MyComponent {
  @State timeTable: TimeTable[] = [
    {
      title: '星期一',
      projects: ['语文', '数学', '英语', '其他']
    },
    {
      title: '星期二',
      projects: ['物理', '化学', '生物']
    },
    {
      title: '星期三',
      projects: ['历史', '地理', '政治']
    },
    {
      title: '星期四',
      projects: ['美术', '音乐', '体育']
    }
  ]
  private data1: MyDataSource = new MyDataSource(this.timeTable);
  private data2: MyDataSource = new MyDataSource(['']);
  private hashMap: HashMap<string,MyDataSource> = new HashMap();
  aboutToAppear(): void {
    for (let index = 0; index < this.timeTable.length; index++) {
      this.hashMap.set(this.timeTable[index].title, new MyDataSource(this.timeTable[index].projects))
    }
  }
  @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)
  }
  build() {
    List({ space: 3 }) {
      LazyForEach(this.data1, (item: TimeTable) => {
        ListItemGroup({ header: this.itemHead(item.title), footer: this.itemFoot(item.projects.length) }) {
          LazyForEach(this.hashMap.get(item.title), (project: string) => {
            ListItem() {
              Text(project)
                .width("100%")
                .height(100)
                .fontSize(20)
                .textAlign(TextAlign.Center)
                .backgroundColor(0xFFFFFF)
            }
          }, (item: string) => item)
        }
        .divider({ strokeWidth: 1, color: Color.Blue }) // 每行之间的分界线
      }, (item: string) => item)
    }.cachedCount(5)
  }
}
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