HarmonyOS应用三之组件生命周期和参数传递

1、生命周期的执行顺序

/** Copyright (c) 2023 Huawei Device Co., Ltd.* Licensed under the Apache License, Version 2.0 (the "License");* you may not use this file except in compliance with the License.* You may obtain a copy of the License at**     http://www.apache.org/licenses/LICENSE-2.0** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*/import { AbilityConstant, UIAbility, Want } from '@kit.AbilityKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
import { window } from '@kit.ArkUI';export default class EntryAbility extends UIAbility {windowStage: window.WindowStage | undefined = undefined;tag: string = 'EntryAbility';domain: number = 0x0000;want: Want | undefined = undefined;launchParam: AbilityConstant.LaunchParam | undefined = undefined;windowStageEventFunc: (data: window.WindowStageEventType) => void = (data: window.WindowStageEventType): void => {hilog.info(this.domain,'Succeeded in enabling the listener for window stage event changes. Data: %{public}',JSON.stringify(data) ?? '');}onCreate(want: Want, launchParam: AbilityConstant.LaunchParam): void {this.want = want;this.launchParam = launchParam;hilog.info(this.domain, this.tag, 'Ability is onCreate.');}onDestroy() {hilog.info(this.domain, this.tag, 'Ability is onDestroy.');}onWindowStageCreate(windowStage: window.WindowStage) {this.windowStage = windowStage;// Setting Event Subscription for WindowStage (Obtained/Out-of-focus, Visible/Invisible)try {windowStage.on('windowStageEvent', this.windowStageEventFunc);} catch (exception) {hilog.error(this.domain,'Failed to enable the listener for window stage event changes. Cause: %{public}',JSON.stringify(exception) ?? '');}// Main window is created, set main page for this ability// Setting UI LoadingwindowStage.loadContent('pages/LifeCyclePage', (err, data) => {if (err.code) {hilog.error(this.domain, 'testTag', 'Failed to load the content. Cause: %{public}s',JSON.stringify(err) ?? '');return;}hilog.info(this.domain, this.tag, 'Succeeded in loading the content. Data: %{public}s',JSON.stringify(data) ?? '');});}onWindowStageDestroy() {// Releasing UI Resources// Unregisters the WindowStage event for getting/out of focus in onWindowStageDestroy()try {this.windowStage?.off('windowStageEvent');} catch (exception) {hilog.error(this.domain, 'Failed to disable the listener for window stage event changes. Cause: %{public}s',JSON.stringify(exception));}}onForeground() {// Ability has brought to foregroundhilog.info(this.domain, this.tag, 'Ability is onForeground.');}onBackground() {// Ability has back to backgroundhilog.info(this.domain, this.tag, 'Ability is onBackground.');}
}

/** Copyright (c) 2023 Huawei Device Co., Ltd.* Licensed under the Apache License, Version 2.0 (the "License");* you may not use this file except in compliance with the License.* You may obtain a copy of the License at**     http://www.apache.org/licenses/LICENSE-2.0** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*/import Logger from '../common/util/Logger';
import CommonConstants from '../common/constants/CommonConstants';@Entry
@Component
struct LifeCyclePage {@State textColor: Color = Color.Black;aboutToAppear() {this.textColor = Color.Blue;Logger.info('[LifeCyclePage]  LifeCyclePage aboutToAppear');}onPageShow() {this.textColor = Color.Brown;Logger.info('[LifeCyclePage]  LifeCyclePage onPageShow');}onPageHide() {Logger.info('[LifeCyclePage]  LifeCyclePage onPageHide');}onBackPress() {this.textColor = Color.Red;Logger.info('[LifeCyclePage]  LifeCyclePage onBackPress');return false;}aboutToDisappear() {Logger.info('[LifeCyclePage]  LifeCyclePage aboutToDisappear');}build() {Column() {Text($r('app.string.hello_message')).fontSize(CommonConstants.DEFAULT_FONT_SIZE).fontColor(this.textColor).margin(CommonConstants.DEFAULT_MARGIN).fontWeight(FontWeight.Bold)}.width(CommonConstants.FULL_WIDTH)}
}

2、页面数据传递

首页跳转第二页时通过router.pushUrl中的routerParams来传递参数。

第二页可以通过router.getParams().src来拿传递过来的值，展示到页面。

3、图片的读取

app.media.banner_pic1读取的就是本地目录media下的该图片。

4、数据的备份和恢复

• BackupExtensionAbility模块提供备份恢复服务相关扩展能力，为应用提供扩展的备份恢复能力。
• onBackup(): void; Extension生命周期回调，在执行备份数据时回调，由开发者提供扩展的备份数据的操作。
• onRestore(bundleVersion: BundleVersion): void;Extension生命周期回调，在执行恢复数据时回调，由开发者提供扩展的恢复数据的操作。
• 当需要进行数据备份时，‌可以通过实现onBackup()方法来实现备份逻辑（可以通过脚本来实现）。‌
• 当需要进行数据恢复时，‌可以通过实现onRestore()方法来实现恢复逻辑（可以通过脚本来实现）。‌
  

5、轮播图

class BannerClass {id: string = '';imageSrc: ResourceStr = '';url: string = '';constructor(id: string, imageSrc: ResourceStr, url: string) {this.id = id;this.imageSrc = imageSrc;this.url = url;}
}@Entry
@Component
struct Index {@State message: string = '快速入门';build() {Column() {Text(this.message).fontSize(24).fontWeight(700).width('100%').textAlign(TextAlign.Start).padding({ left: 16 }).fontFamily('HarmonyHeiTi-Bold').lineHeight(33)Banner()}.width('100%').height('100%').backgroundColor('#F1F3F5')}
}@Preview
@Component
struct Banner {@State bannerList: Array<BannerClass> = [new BannerClass('pic0', $r('app.media.banner_pic0'),'https://developer.huawei.com/consumer/cn/training/course/video/C101718352529709527'),new BannerClass('pic1', $r('app.media.banner_pic1'),'https://developer.huawei.com/consumer/cn/'),new BannerClass('pic2', $r('app.media.banner_pic2'),'https://developer.huawei.com/consumer/cn/deveco-studio/'),new BannerClass('pic3', $r('app.media.banner_pic3'),'https://developer.huawei.com/consumer/cn/arkts/'),new BannerClass('pic4', $r('app.media.banner_pic4'),'https://developer.huawei.com/consumer/cn/arkui/'),new BannerClass('pic5', $r('app.media.banner_pic5'),'https://developer.huawei.com/consumer/cn/sdk')];build() {Swiper() {ForEach(this.bannerList, (item: BannerClass, index: number) => {Image(item.imageSrc).objectFit(ImageFit.Contain).width('100%').padding({ top: 11, left: 16, right: 16 }).borderRadius(16)}, (item: BannerClass, index: number) => item.id)}.autoPlay(true).loop(true).indicator(new DotIndicator().color('#1a000000').selectedColor('#0A59F7'))}
}

使用数组存储轮播图片，遍历展示。

• loop：设置是否启用循环滑动时调用。
• autoPlay：设置子组件是否自动播放时调用。
• indicator：设置指示器已启用，或设置类型样式。

6、页面布局图

class BannerClass {id: string = '';imageSrc: ResourceStr = '';url: string = '';constructor(id: string, imageSrc: ResourceStr, url: string) {this.id = id;this.imageSrc = imageSrc;this.url = url;}
}class ArticleClass {id: string = '';imageSrc: ResourceStr = '';title: string = '';brief: string = '';webUrl: string = '';constructor(id: string, imageSrc: ResourceStr, title: string, brief: string, webUrl: string) {this.id = id;this.imageSrc = imageSrc;this.title = title;this.brief = brief;this.webUrl = webUrl;}
}@Entry
@Component
struct Index {@State message: string = '快速入门';build() {Column() {Text(this.message).fontSize(24).fontWeight(700).width('100%').textAlign(TextAlign.Start).padding({ left: 16 }).fontFamily('HarmonyHeiTi-Bold').lineHeight(33)Scroll() {Column() {Banner()EnablementView()TutorialView()}}.layoutWeight(1).scrollBar(BarState.Off).align(Alignment.TopStart)}.width('100%').height('100%').backgroundColor('#F1F3F5')}
}@Preview
@Component
struct Banner {@State bannerList: Array<BannerClass> = [new BannerClass('pic0', $r('app.media.banner_pic0'),'https://developer.huawei.com/consumer/cn/training/course/video/C101718352529709527'),new BannerClass('pic1', $r('app.media.banner_pic1'),'https://developer.huawei.com/consumer/cn/'),new BannerClass('pic2', $r('app.media.banner_pic2'),'https://developer.huawei.com/consumer/cn/deveco-studio/'),new BannerClass('pic3', $r('app.media.banner_pic3'),'https://developer.huawei.com/consumer/cn/arkts/'),new BannerClass('pic4', $r('app.media.banner_pic4'),'https://developer.huawei.com/consumer/cn/arkui/'),new BannerClass('pic5', $r('app.media.banner_pic5'),'https://developer.huawei.com/consumer/cn/sdk')];build() {Swiper() {ForEach(this.bannerList, (item: BannerClass, index: number) => {Image(item.imageSrc).objectFit(ImageFit.Contain).width('100%').padding({ top: 11, left: 16, right: 16 }).borderRadius(16)}, (item: BannerClass, index: number) => item.id)}.autoPlay(true).loop(true).indicator(new DotIndicator().color('#1a000000').selectedColor('#0A59F7'))}
}@Component
struct TutorialItem {@Prop tutorialItem: ArticleClass;build() {Row() {Column() {Text(this.tutorialItem.title).height(19).width('100%').fontSize(14).textAlign(TextAlign.Start).textOverflow({ overflow: TextOverflow.Ellipsis }).maxLines(1).fontWeight(400).margin({ top: 4 })Text(this.tutorialItem.brief).height(32).width('100%').fontSize(12).textAlign(TextAlign.Start).textOverflow({ overflow: TextOverflow.Ellipsis }).maxLines(2).fontWeight(400).fontColor('rgba(0, 0, 0, 0.6)').margin({ top: 5 })}.height('100%').layoutWeight(1).alignItems(HorizontalAlign.Start).margin({ right: 12 })Image(this.tutorialItem.imageSrc).height(64).width(108).objectFit(ImageFit.Cover).borderRadius(16)}.width('100%').height(88).borderRadius(16).backgroundColor(Color.White).padding(12).alignItems(VerticalAlign.Top)}
}@Component
struct EnablementItem {@Prop enablementItem: ArticleClass;build() {Column() {Image(this.enablementItem.imageSrc).width('100%').objectFit(ImageFit.Cover).height(96).borderRadius({topLeft: 16,topRight: 16})Text(this.enablementItem.title).height(19).width('100%').fontSize(14).textAlign(TextAlign.Start).textOverflow({ overflow: TextOverflow.Ellipsis }).maxLines(1).fontWeight(400).padding({ left: 12, right: 12 }).margin({ top: 8 })Text(this.enablementItem.brief).height(32).width('100%').fontSize(12).textAlign(TextAlign.Start).textOverflow({ overflow: TextOverflow.Ellipsis }).maxLines(2).fontWeight(400).fontColor('rgba(0, 0, 0, 0.6)').padding({ left: 12, right: 12 }).margin({ top: 2 })}.width(160).height(169).borderRadius(16).backgroundColor(Color.White)}
}@Component
struct EnablementView {@State enablementList: Array<ArticleClass> = [new ArticleClass('1', $r('app.media.enablement_pic1'), 'HarmonyOS第一课','基于真实的开发场景，提供向导式学习，多维度融合课程等内容，给开发者提供全新的学习体验。','https://developer.huawei.com/consumer/cn/doc/harmonyos-video-courses/video-tutorials-0000001443535745'),new ArticleClass('2', $r('app.media.enablement_pic2'), '开发指南','提供系统能力概述、快速入门，用于指导开发者进行场景化的开发。指南涉及到的知识点包括必要的背景知识、符合开发者实际开发场景的操作任务流（开发流程、开发步骤、调测验证）以及常见问题等。','https://developer.huawei.com/consumer/cn/doc/harmonyos-guides/application-dev-guide-0000001630265101'),new ArticleClass('3', $r('app.media.enablement_pic3'), '最佳实践','针对新发布特性及热点特性提供详细的技术解析和开发最佳实践。','https://developer.huawei.com/consumer/cn/doc/harmonyos-guides/topic-architecture-0000001678045510'),new ArticleClass('4', $r('app.media.enablement_pic4'), 'Codelabs','以教学为目的的代码样例及详细的开发指导，帮助开发者一步步地完成指定场景的应用开发并掌握相关知识。Codelabs将最新的鸿蒙生态应用开发技术与典型场景结合，让开发者快速地掌握开发高质量应用的方法。同时支持互动式操作，通过文字、代码和效果联动为开发者带来更佳的学习体验。','https://developer.huawei.com/consumer/cn/doc/harmonyos-codelabs/codelabs-0000001443855957'),new ArticleClass('5', $r('app.media.enablement_pic5'), 'Sample','面向不同类型的开发者提供的鸿蒙生态应用开发优秀实践，每个Sample Code都是一个可运行的工程，为开发者提供实例化的代码参考。','https://developer.huawei.com/consumer/cn/doc/harmonyos-samples/samples-0000001162414961'),new ArticleClass('6', $r('app.media.enablement_pic6'), 'API参考','面向开发者提供鸿蒙系统开放接口的全集，供开发者了解具体接口使用方法。API参考详细地描述了每个接口的功能、使用限制、参数名、参数类型、参数含义、取值范围、权限、注意事项、错误码及返回值等。','https://developer.huawei.com/consumer/cn/doc/harmonyos-references/development-intro-0000001580026066'),new ArticleClass('7', $r('app.media.enablement_pic7'), 'FAQ','开发者常见问题的总结，开发者可以通过FAQ更高效地解决常见问题。FAQ会持续刷新，及时呈现最新的常见问题。','https://developer.huawei.com/consumer/cn/doc/harmonyos-faqs/faqs-development-0000001753952202'),new ArticleClass('8', $r('app.media.enablement_pic8'), '开发者论坛', '和其他应用开发者交流技术、共同进步。','https://developer.huawei.com/consumer/cn/forum/home?all=1'),];build() {Column() {Text('赋能套件').fontColor('#182431').fontSize(16).fontWeight(500).fontFamily('HarmonyHeiTi-medium').textAlign(TextAlign.Start).padding({ left: 16 }).margin({ bottom: 8.5 })Grid() {ForEach(this.enablementList, (item: ArticleClass) => {GridItem() {EnablementItem({ enablementItem: item })}}, (item: ArticleClass) => item.id)}.rowsTemplate('1fr').columnsGap(8).scrollBar(BarState.Off).height(169).padding({ top: 2, left: 16, right: 16 })}.margin({ top: 18 }).alignItems(HorizontalAlign.Start)}
}@Component
struct TutorialView {@State tutorialList: Array<ArticleClass> = [new ArticleClass('1', $r('app.media.tutorial_pic1'), 'Step1 环境的搭建','本篇教程实现了快速入门——一个用于了解和学习HarmonyOS的应用程序。','https://developer.huawei.com/consumer/cn/forum/home?all=1'),new ArticleClass('2', $r('app.media.tutorial_pic2'), 'Step2 使用Swiper构建运营广告位','Swiper组件提供滑动轮播显示的能力。Swiper本身是一个容器组件，当设置了多个子组件后，可以对这些子组件进行轮播显示。','https://developer.huawei.com/consumer/cn/forum/home?all=1'),new ArticleClass('3', $r('app.media.tutorial_pic3'), 'Step3 创建和组合视图','Item定义子组件相关特征。相关组件支持使用条件渲染、循环渲染、懒加载等方式生成子组件。','https://developer.huawei.com/consumer/cn/forum/home?all=1'),new ArticleClass('4', $r('app.media.tutorial_pic4'), 'Step4 网格和列表组建的使用','网格和列表组件中，当Item达到一定数量，内容超过屏幕大小时，可以自动提供滚动功能，适合用于呈现同类数据类型或数据类型集','https://developer.huawei.com/consumer/cn/forum/home?all=1'),new ArticleClass('5', $r('app.media.tutorial_pic5'), 'Step5 应用架构设计基础——MVVM模式','ArkUI采取MVVM = Model + View + ViewModel模式，将数据与视图绑定在一起，更新数据的时候直接更新视图。','https://developer.huawei.com/consumer/cn/forum/home?all=1'),new ArticleClass('6', $r('app.media.tutorial_pic6'), 'Step6 应用架构设计基础——三层架构','为了更好地适配复杂应用的开发，建议采用三层架构的方式对整个应用的功能进行模块化，实现高内聚、低耦合开发。','https://developer.huawei.com/consumer/cn/forum/home?all=1'),new ArticleClass('7', $r('app.media.tutorial_pic7'), 'Step6 ArkWeb页面适配','ArkWeb（方舟Web）提供了Web组件，用于在应用程序中显示Web页面内容，为开发者提供页面加载、页面交互、页面调试等能力。','https://developer.huawei.com/consumer/cn/forum/home?all=1'),new ArticleClass('8', $r('app.media.tutorial_pic8'), 'Step7 数据驱动UI更新', '数据更新的同时会直接驱动UI的改变','xxx'),new ArticleClass('9', $r('app.media.tutorial_pic9'), 'Step8 设置组件导航','Navigation组件适用于模块内页面切换，一次开发，多端部署场景。通过组件级路由能力实现更加自然流畅的转场体验，并提供多种标题栏样式来呈现更好的标题和内容联动效果。','https://developer.huawei.com/consumer/cn/forum/home?all=1'),new ArticleClass('10', $r('app.media.tutorial_pic10'), 'Step9 原生智能：AI语音朗读','文本转语音服务提供将文本信息转换为语音并进行播报的能力，便于用户与设备进行互动，实现实时语音交互，文本播报。','https://developer.huawei.com/consumer/cn/forum/home?all=1'),new ArticleClass('11', $r('app.media.tutorial_pic11'), 'Step10 原生互联：分布式流转','流转能力打破设备界限，多设备联动，使用户应用程序可分可合、可流转，实现如邮件跨设备编辑、多设备协同健身、多屏游戏等分布式业务。','https://developer.huawei.com/consumer/cn/forum/home?all=1'),new ArticleClass('12', $r('app.media.tutorial_pic12'), 'Step11 一次开发，多端部署','一套代码工程，一次开发上架，多端按需部署。支撑开发者快速高效的开发支持多种终端设备形态的应用，实现对不同设备兼容的同时，提供跨设备的流转、迁移和协同的分布式体验。','https://developer.huawei.com/consumer/cn/forum/home?all=1'),];build() {Column() {Text('入门教程').fontColor('#182431').fontSize(16).fontWeight(500).fontFamily('HarmonyHeiTi-medium').textAlign(TextAlign.Start).padding({ left: 16 }).margin({ bottom: 8.5 })List({ space: 12 }) {ForEach(this.tutorialList, (item: ArticleClass) => {ListItem() {TutorialItem({ tutorialItem: item })}}, (item: ArticleClass) => item.id)}.scrollBar(BarState.Off).padding({ left: 16, right: 16 })}.margin({ top: 18 }).alignItems(HorizontalAlign.Start)}
}

页面执行顺序不是自上而下的执行：

1号执行入口组件：

2号执行预览组件：

3号带有@Component的，@State自上而下执行，执行到的调用方法里面有@Prop组件的再调用。