HarmonyOS 懒加载列表更改属性UI不刷新

export  class BasicDataSource implements IDataSource {
  private listeners: DataChangeListener[] = [];

  public totalCount(): number {
    return 0;
  }

  public getData(index: number): Object {
    return index;
  }

  // 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) {
      this.listeners.push(listener);
    }
  }

  // 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) {
      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组件需要在index对应索引处添加子组件
  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);
    })
  }

  notifyDataMove(from: number, to: number): void {
    this.listeners.forEach(listener => {
      listener.onDataMove(from, to);
    })
  }
}
@Observed
export class ObservedArray<T> extends Array<T> {
  constructor(args: T[]) {
    if (args instanceof Array) {
      super(...args);
    } else {
      super(args)
    }
  }
}
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import { PullToRefresh, PullToRefreshConfigurator } from '@ohos/pulltorefresh';
import { plainToInstance } from 'class-transformer';
import { BasicDataSource } from '../../entryability/adapter/BasicDataSource';
import { ObservedArray } from '../../entryability/data/ObservedArray';

/**
 * @Author klxt002
 * @Date 2024/7/30 20:19
 * @version 1.0
 * @注释
 */
@Entry
@Component
struct TestPage {
  //type: string = ((router.getParams() as Record<string, string|number>)?.type?.toString()) ?? '0'

  // PullToRefresh组件必需参数
  @State pullData: string[] = [];
  // 创建用于懒加载的数据对象
  @State resultData: DataSource = new DataSource();
  @State hasData: boolean = false //有数据
  scroller: Scroller = new Scroller()
  // 下拉刷新组件配置对象
  private pullToRefreshConfigurator: PullToRefreshConfigurator =
    new PullToRefreshConfigurator().setHasRefresh(true).setHasLoadMore(true).setLoadTextSize(13);
  @State heightNum: string = '89'


  aboutToAppear(): void {
    if (!this.hasData) {
      this.requestData()
    }
  }

  build() {
    RelativeContainer() {
      if (this.hasData) {
        PullToRefresh({
          // TODO: 知识点：使用PullToRefresh组件时需要先绑定数据与主体布局。若使用LazyForEach组件渲染列表时，需将UI方法使用@Builder修饰并传入customList属性中。
          // 必传项，列表组件所绑定的数据
          data: $resultData,
          // 必传项，需绑定传入主体布局内的列表或宫格组件
          scroller: this.scroller,
          // 必传项，自定义主体布局，内部有列表或宫格组件
          customList: () => {
            // 一个用@Builder修饰过的UI方法
            this.getListView()
          },
          // // TODO: 知识点：设置onRefresh下拉刷新回调方法，该方法必须返回一个Promise类型。
          onRefresh: () => {
            return new Promise<string>((resolve, reject) => {
              this.requestData()
              resolve('')
            });
          },
          refreshConfigurator: (this.pullToRefreshConfigurator)
        })
          .height('100%')
          .width(`100%`)
          .padding({
            top: this.heightNum,
          })
          .alignRules({
            top: { anchor: '__container__', align: VerticalAlign.Top },
            middle: { anchor: '__container__', align: HorizontalAlign.Center }
          })
          .id('pullView')

      }


    }
    .height('100%')
    .width('100%')
  }

  // 必须使用@Builder修饰方法
  @Builder
  private getListView() {
    List({
      space: 10, scroller: this.scroller
    }) {
      // TODO: 性能知识点：使用懒加载组件渲染数据
      LazyForEach(this.resultData, (item: TestDemo, index: number) => {
        ListItem() {
          Text(item.name ?? '' + item.age ?? '0')
            .width('100%')
            .height('10%')
            .backgroundColor(Color.Pink)
            .textAlign(TextAlign.Center)
            .onClick(() => {
              item.name += '1'
            })
        }
      }, (item: TestDemo, index?: number) => JSON.stringify(item) + index);
    }.width(`100%`)
    .height('100%')

    // TODO: 知识点：必须设置列表为滑动到边缘无效果，否则无法触发pullToRefresh组件的上滑下拉方法。
    .edgeEffect(EdgeEffect.None)
  }

  private isChange = false
  /**
   * 请求数据
   * @param page
   * @param success
   * @param error
   */
  requestData() {

    let json: Record<string, string | number>[] =
      [{ 'name': 'abc', 'age': 12 }, { 'name': 'abc', 'age': 12 }, { 'name': 'abc', 'age': 12 }]
    if (this.isChange) {
      json = [{ 'name': 'abc2', 'age': 13 }, { 'name': 'abc2', 'age': 12 }, { 'name': 'abc', 'age': 12 }]
    }
    this.isChange = !this.isChange

    let jsonStr: string = JSON.stringify(json)
    let data: ObservedArray<TestDemo> = JSON.parse(jsonStr) as ObservedArray<TestDemo>


    setTimeout(() => {
      this.resultData.clear()
      this.resultData.pushDataAll(data)
    }, 1000)
  }
}

@Observed
export class TestDemo {
  name?: string
  age?: number
}

// 懒加载列表对象
class DataSource extends BasicDataSource {
  dataArray: Array<TestDemo> = [];

  public isEmpty(): boolean {
    return this.dataArray.length <= 0;
  }

  public isNotEmpty(): boolean {
    return this.totalCount() > 0;
  }

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

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

  public addData(index: number, data: TestDemo): void {
    let item = plainToInstance(TestDemo, data)
    this.dataArray.splice(index, 0, item);
    this.notifyDataAdd(index);
  }

  public pushData(data: TestDemo): void {
    let item = plainToInstance(TestDemo, data)
    this.dataArray.push(item);
    this.notifyDataAdd(this.dataArray.length - 1);
  }

  public pushDataAll(data: TestDemo[]): void {
    data.forEach((testItem: TestDemo) => {
      let item = plainToInstance(TestDemo, testItem)
      this.dataArray.push(item);
    })
    this.notifyDataAdd(this.dataArray.length - 1);
  }

  public reloadData(data: TestDemo[]): void {
    data.forEach((testItem: TestDemo) => {
      let item = plainToInstance(TestDemo, testItem)
      this.dataArray.push(item);
    })
    this.notifyDataReload();
  }

  public clear(): void {
    this.dataArray = [];
  }
}
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