seo网站架构,在什么网站可以做推广,传媒公司合同模板,做美食网站的模板鸿蒙开发深入浅出03#xff08;封装通用LazyForEach实现懒加载#xff09; 1、效果展示2、ets/models/BasicDataSource.ets3、ets/models/HomeData.ets4、ets/api/home.ets5、ets/pages/Home.ets6、ets/views/Home/SwiperLayout.ets7、后端代码 1、效果展示 2、ets/models/Ba… 鸿蒙开发深入浅出03封装通用LazyForEach实现懒加载 1、效果展示2、ets/models/BasicDataSource.ets3、ets/models/HomeData.ets4、ets/api/home.ets5、ets/pages/Home.ets6、ets/views/Home/SwiperLayout.ets7、后端代码 1、效果展示 2、ets/models/BasicDataSource.ets
// BasicDataSource实现了IDataSource接口用于管理listener监听以及通知LazyForEach数据更新
// https://developer.huawei.com/consumer/cn/doc/harmonyos-guides-V5/arkts-rendering-control-lazyforeach-V5#stringdata%E7%B1%BB%E5%9E%8B%E6%95%B0%E7%BB%84%E7%9A%84basicdatasource%E4%BB%A3%E7%A0%81
export default class BasicDataSourceT implements IDataSource {// 内部用来触发UI更新的对象private listeners: DataChangeListener[] [];// 管理的数据private list: T[] [];// 返回数据总长度public totalCount(): number {return this.list.length;}// 读取对应下标的数据public getData(index: number): T {return this.list[index];}// 保存单个数据public setData(item: T) {// 只会更新数据不会更新UIthis.list.push(item);// 更新UI操作this.notifyDataAdd(this.list.length - 1);}// 更新所有列表数据public setList(list: T[]) {this.list list;// 全部通知修改this.notifyDataReload();}// 该方法为框架侧调用为LazyForEach组件向其数据源处添加listener监听registerDataChangeListener(listener: DataChangeListener): void {if (this.listeners.indexOf(listener) 0) {console.info(add listener);this.listeners.push(listener);}}// 该方法为框架侧调用为对应的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) {console.info(remove listener);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);// 写法2listener.onDatasetChange([{type: DataOperationType.ADD, index: index}]);})}// 通知LazyForEach组件在index对应索引处数据有变化需要重建该子组件notifyDataChange(index: number): void {this.listeners.forEach(listener {listener.onDataChange(index);// 写法2listener.onDatasetChange([{type: DataOperationType.CHANGE, index: 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);// 写法2listener.onDatasetChange([{type: DataOperationType.DELETE, index: index}]);})}// 通知LazyForEach组件将from索引和to索引处的子组件进行交换notifyDataMove(from: number, to: number): void {this.listeners.forEach(listener {listener.onDataMove(from, to);// 写法2listener.onDatasetChange(// [{type: DataOperationType.EXCHANGE, index: {start: from, end: to}}]);})}notifyDatasetChange(operations: DataOperation[]): void {this.listeners.forEach(listener {listener.onDatasetChange(operations);})}
}3、ets/models/HomeData.ets 注意因为我们这个模块使用了BasicDataSource.ets所以从鸿蒙开发深入浅出02封装Axios请求、渲染Swiper需改为ets后缀。 import BasicDataSource from ./BasicDataSource;Observed
export class BasicListDataSourceT extends BasicDataSourceT {lists: T[] [];
}export interface IHomeData {bannerList: IBannerListnavList: INavListtileList: ITileListplanList: IPlanListadPicture: string
}// 计划列表类型
export interface IPlanItem {id: numberimageURL: string
}export type IPlanList IPlanItem[]// 瓷片列表类型
export interface ITileItem {id: numberimageURL: stringtitle: stringsub_title: string
}export type ITileList ITileItem[]// 导航列表类型
export interface INavItem {id: numbertitle: stringimageURL: string
}export type INavList INavItem[]// 轮播图类型
export interface IBannerItem {id: numbername: stringimageURL: string
}export type IBannerList IBannerItem[]4、ets/api/home.ets 同 3 所述home.ts 也需改为 ets 结尾并添加返回类型。 import { http } from ../utils/http
import type { IHomeData } from ../models/HomeData// 获取页面数据
export const getHomeDataApi (): PromiseIHomeData {return http.getIHomeData(/home/info)
}5、ets/pages/Home.ets
import { getHomeDataApi } from ../api/home
import { BasicListDataSource, IBannerItem, IBannerList } from ../models/HomeData
import SwiperLayout from ../views/Home/SwiperLayout/*** MyHouseApplication #项目的名称* Home.ets #文件名称* Created by zhong ON 2025/2/23 #作者及添加日期*/
Component
export default struct Home {State bannerList: BasicListDataSourceIBannerItem new BasicListDataSource();// 获取首页数据的函数getHomeData async () {const result await getHomeDataApi();this.bannerList.setList(result.bannerList);}// 生命周期函数初始化页面时触发aboutToAppear(): void {this.getHomeData();}build() {Scroll() {Column() {SwiperLayout({ bannerList: this.bannerList });}.width(100%)}.width(100%).height(100%).scrollBar(BarState.Off).align(Alignment.TopStart)}
}
6、ets/views/Home/SwiperLayout.ets
/*** MyHouseApplication #项目的名称* SwiperLayout.ets #文件名称* Created by zhong ON 2025/2/23 #作者及添加日期*/
import { IBannerItem, BasicListDataSource } from ../../models/HomeDataComponent
export default struct SwiperLayout {ObjectLink bannerList: BasicListDataSourceIBannerItem;build() {Swiper() {LazyForEach(this.bannerList, (banner: IBannerItem) {Image(banner.imageURL).width(100%).height(100%).objectFit(ImageFit.Fill)}, (banner: IBannerItem) banner.id )}.width(100%).height(211 - 36).indicator(new DotIndicator().color($r(app.color.indicator_color)).selectedColor($r(app.color.indicator_active_color)))}
}
7、后端代码 双击 zufangBackend-windows-amd64.exe 运行
