#鸿蒙通关秘籍#如何创建一个用于瀑布流的自定义数据源类？

export class WaterFlowDataSource implements IDataSource {
  private dataArray: number[] = []
  private listeners: DataChangeListener[] = []

  constructor() {
    for (let i = 0; i < 100; i++) {
      this.dataArray.push(i)
    }
  }

  getData(index: number): number {
    return this.dataArray[index]
  }

  notifyDataReload(): void {
    this.listeners.forEach(listener => {
      listener.onDataReloaded()
    })
  }

  notifyDataAdd(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataAdd(index)
    })
  }

  totalCount(): number {
    return this.dataArray.length
  }

  registerDataChangeListener(listener: DataChangeListener): void {
    if (this.listeners.indexOf(listener) < 0) {
      this.listeners.push(listener)
    }
  }

  unregisterDataChangeListener(listener: DataChangeListener): void {
    const pos = this.listeners.indexOf(listener)
    if (pos >= 0) {
      this.listeners.splice(pos, 1)
    }
  }

  addLastItem(): void {
    this.dataArray.splice(this.dataArray.length, 0, this.dataArray.length)
    this.notifyDataAdd(this.dataArray.length - 1)
  }
}
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