📚往期笔录记录✏️：

✏️ 鸿蒙（HarmonyOS）北向开发知识点记录~
✏️ 鸿蒙（OpenHarmony）南向开发保姆级知识点汇总~
✏️ 鸿蒙应用开发与鸿蒙系统开发哪个更有前景？
✏️ 嵌入式开发适不适合做鸿蒙南向开发？看完这篇你就了解了~
✏️ 对于大前端开发来说，转鸿蒙开发究竟是福还是祸？
✏️ 鸿蒙岗位需求突增！移动端、PC端、IoT到底该怎么选？
✏️ 记录一场鸿蒙开发岗位面试经历~
✏️ 持续更新中……

通过DevEco Studio开发平台创建PageAbility时，DevEco Studio会在app.js/app.ets中默认生成onCreate()和onDestroy()方法，其他方法需要开发者自行实现。接口说明参见前述章节，创建PageAbility示例如下：

import featureAbility from '@ohos.ability.featureAbility';
import Logger from '../utils/Logger';

const TAG: string = 'MainAbility';

class MainAbility {
  onCreate() {
    // 获取context并调用相关方法
    let context = featureAbility.getContext();
    context.getBundleName((data, bundleName) => {
      Logger.info(TAG, 'ability bundleName:' + bundleName);
    });
    Logger.info(TAG, 'Application onCreate');
  }

  onDestroy() {
    Logger.info(TAG, 'Application onDestroy');
  }

  onShow(): void {
    Logger.info(TAG, 'Application onShow');
  }

  onHide(): void {
    Logger.info(TAG, 'Application onHide');
  }

  onActive(): void {
    Logger.info(TAG, 'Application onActive');
  }

  onInactive(): void {
    Logger.info(TAG, 'Application onInactive');
  }

  onNewWant() {
    Logger.info(TAG, 'Application onNewWant');
  }
}

export default new MainAbility();
PageAbility创建成功后，其abilities相关的配置项在config.json中体现，一个名字为EntryAbility的config.json配置文件示例如下：

{
  ...
  "module": {
    ...
    "abilities": [
      {
        "skills": [
          {
            "entities": [
              "entity.system.home"
            ],
            "actions": [
              "action.system.home"
            ]
          }
        ],
        "orientation": "unspecified",
        "formsEnabled": false,
        "name": ".MainAbility",
        "srcLanguage": "ets",
        "srcPath": "MainAbility",
        "icon": "$media:icon",
        "description": "$string:MainAbility_desc",
        "label": "$string:MainAbility_label",
        "type": "page",
        "visible": true,
        "launchType": "singleton"
      },
      ...
    ]
    ...
  }
}

FA模型中，可以通过featureAbility的getContext接口获取应用上下文，进而使用上下文提供的能力。

表1 featureAbility接口说明

接口名接口描述
getContext()获取应用上下文。

通过getContext获取应用上下文并获取分布式目录的示例如下：

import featureAbility from '@ohos.ability.featureAbility';
import fs from '@ohos.file.fs';
import promptAction from '@ohos.promptAction';
import Logger from '../../utils/Logger';

const TAG: string = 'PagePageAbilityFirst';

(async (): Promise<void> => {
  let dir: string;
  try {
    Logger.info(TAG, 'Begin to getOrCreateDistributedDir');
    dir = await featureAbility.getContext().getOrCreateDistributedDir();
    promptAction.showToast({
      message: dir
    });
    Logger.info(TAG, 'distribute dir is ' + dir);
    let fd: number;
    let path = dir + '/a.txt';
    fd = fs.openSync(path, fs.OpenMode.READ_WRITE).fd;
    fs.close(fd);
  } catch (error) {
    Logger.error(TAG, `getOrCreateDistributedDir failed with : ${error}`);
  }
})()

启动本地PageAbility

PageAbility相关的能力通过featureAbility提供，启动本地Ability通过featureAbility中的startAbility接口实现。

表1 featureAbility接口说明

接口名接口描述
startAbility(parameter: StartAbilityParameter)启动Ability。
startAbilityForResult(parameter: StartAbilityParameter)启动Ability，并在该Ability被销毁时返回执行结果。

如下示例通过startAbility显式启动PageAbility。启动Ability的参数包含want，关于want的说明详见 对象间信息传递载体Want ，相应的，隐式启动与显式启动也不在此赘述。

import featureAbility from '@ohos.ability.featureAbility'
import Want from '@ohos.app.ability.Want';
import Logger from '../../utils/Logger';

const TAG: string = 'PagePageAbilityFirst';

  try {
    Logger.info(TAG, 'Begin to start ability');
    let want: Want = {
      bundleName: 'com.samples.famodelabilitydevelop',
      moduleName: 'entry',
      abilityName: 'com.samples.famodelabilitydevelop.PageAbilitySingleton'
    };
    await featureAbility.startAbility({ want: want });
    Logger.info(TAG, `Start ability succeed`);
  }
  catch (error) {
    Logger.error(TAG, 'Start ability failed with ' + error);
  }
})()

停止PageAbility

停止PageAbility通过featureAbility中的terminateSelf接口实现。

表1 featureAbility接口说明

接口名接口描述
terminateSelf()停止Ability。
terminateSelfWithResult(parameter: AbilityResult)设置该PageAbility停止时返回给调用者的结果及数据并停止Ability。

如下示例展示了停止Ability的方法。

import featureAbility from '@ohos.ability.featureAbility';
import Logger from '../../utils/Logger';

const TAG: string = 'PagePageAbilityFirst';

(async (): Promise<void> => {
  try {
    Logger.info(TAG, 'Begin to terminateSelf');
    await featureAbility.terminateSelf();
    Logger.info(TAG, 'terminateSelf succeed');
  } catch (error) {
    Logger.error(TAG, 'terminateSelf failed with ' + error);
  }
})()

启动指定页面

当PageAbility的启动模式设置为单例时（具体设置方法和典型场景示例见 PageAbility的启动模式 ，缺省情况下是单实例模式），若PageAbility已被拉起，再次启动PageAbility会触发onNewWant回调（即非首次拉起）。应用开发者可以通过want传递启动参数，例如开发者希望指定页面启动PageAbility，可以通过want中的parameters参数传递pages信息，具体示例代码如下：

调用方PageAbility的app.ets中或者page中，使用startAbility再次拉起PageAbility，通过want中的uri参数传递页面信息：

import featureAbility from '@ohos.ability.featureAbility';
import Want from '@ohos.app.ability.Want';
import Logger from '../../utils/Logger';

const TAG: string = 'PagePageAbilityFirst';

(async (): Promise<void> => {
  let wantInfo: Want = {
    bundleName: 'com.samples.famodelabilitydevelop',
    abilityName: 'com.samples.famodelabilitydevelop.PageAbilitySingleton',
    parameters: { page: 'pages/second' }
  };
  featureAbility.startAbility({ want: wantInfo }).then((data) => {
    Logger.debug(TAG, `restartAbility success : ${data}`);
  });
})()

在目标端PageAbility的onNewWant回调中获取包含页面信息的want参数：

// GlobalContext.ts 构造单例对象
export class GlobalContext {
  private constructor() {
  }

  private static instance: GlobalContext;
  private _objects = new Map<string, Object>();

  public static getContext(): GlobalContext {
    if (!GlobalContext.instance) {
      GlobalContext.instance = new GlobalContext();
    }
    return GlobalContext.instance;
  }

  getObject(value: string): Object | undefined {
    return this._objects.get(value);
  }

  setObject(key: string, objectClass: Object): void {
    this._objects.set(key, objectClass);
  }
}

import Want from '@ohos.app.ability.Want';
import featureAbility from '@ohos.ability.featureAbility';
import { GlobalContext } from '../utils/GlobalContext';

class PageAbilitySingleton {
  onNewWant(want: Want) {
    featureAbility.getWant().then((want) => {
      GlobalContext.getContext().setObject('newWant', want);
    })
  }
}

export default new PageAbilitySingleton();

在目标端页面的自定义组件中获取包含页面信息的want参数并根据uri做路由处理：

import Want from '@ohos.app.ability.Want';
import router from '@ohos.router';
import { GlobalContext } from '../../utils/GlobalContext';

@Entry
@Component
struct First {
  onPageShow() {
    let newWant = GlobalContext.getContext().getObject('newWant') as Want;
    if (newWant) {
      if (newWant.parameters) {
        if (newWant.parameters.page) {
          router.pushUrl({ url: newWant.parameters.page as string});
          GlobalContext.getContext().setObject("newWant", undefined)
        }
      }
    }
  }

  build() {
    Column() {
      Row() {
        Text($r('app.string.singleton_first_title'))
          .fontSize(24)
          .fontWeight(FontWeight.Bold)
          .textAlign(TextAlign.Start)
          .margin({ top: 12, bottom: 11, right: 24, left: 24 })
      }
      .width('100%')
      .height(56)
      .justifyContent(FlexAlign.Start)

      Image($r('app.media.pic_empty'))
        .width(120)
        .height(120)
        .margin({ top: 224 })

      Text($r('app.string.no_content'))
        .fontSize(14)
        .margin({ top: 8, bottom: 317, right: 152, left: 152 })
        .fontColor($r('app.color.text_color'))
        .opacity(0.4)
    }
    .width('100%')
    .height('100%')
    .backgroundColor($r('app.color.backGrounding'))
  }
}

当PageAbility的启动模式设置为多实例模式或为首次启动单例模式的PageAbility时（具体设置方法和典型场景示例见 PageAbility的启动模式 ），在调用方PageAbility中，通过want中的parameters参数传递要启动的指定页面的pages信息，调用startAbility()方法启动PageAbility。被调用方可以在onCreate中使用featureAbility的getWant方法获取want，再通过调用router.pushUrl实现启动指定页面。

调用方的页面中实现按钮点击触发startAbility方法启动目标端PageAbility，startAbility方法的入参want中携带指定页面信息，示例代码如下：

import featureAbility from '@ohos.ability.featureAbility';
import Want from '@ohos.app.ability.Want';
import { BusinessError } from '@ohos.base';
import fs from '@ohos.file.fs';
import promptAction from '@ohos.promptAction';
import worker from '@ohos.worker';
import Logger from '../../utils/Logger';

const TAG: string = 'PagePageAbilityFirst';

@Entry
@Component
struct PagePageAbilityFirst {
  build() {
    Column() {
      Row() {
        Flex({ justifyContent: FlexAlign.Start, alignContent: FlexAlign.Center }) {
          Text($r('app.string.pageAbility_first_button'))
            .fontSize(24)
            .fontWeight(FontWeight.Bold)
            .textAlign(TextAlign.Start)
            .margin({ top: 12, bottom: 11, right: 24, left: 24 })
        }
      }
      .width('100%')
      .height(56)
      .justifyContent(FlexAlign.Start)
      .backgroundColor($r('app.color.backGrounding'))

      List({ initialIndex: 0 }) {
        ...
        ListItem() {
          Flex({ justifyContent: FlexAlign.SpaceBetween, alignContent: FlexAlign.Center }) {
            Text($r('app.string.start_standard_first_button'))
              .textAlign(TextAlign.Start)
              .fontWeight(FontWeight.Medium)
              .margin({ top: 17, bottom: 17, left: 12, right: 92 })
              .fontSize(16)
              .width(232)
              .height(22)
              .fontColor($r('app.color.text_color'))
          }
          .onClick(() => {
            let want: Want = {
              bundleName: 'com.samples.famodelabilitydevelop',
              abilityName: 'com.samples.famodelabilitydevelop.PageAbilityStandard',
              parameters: { page: 'pages/first' }
            };
            featureAbility.startAbility({ want: want }).then((data) => {
              Logger.info(TAG, `startAbility finish:${data}`);
            }).catch((err: BusinessError) => {
              Logger.info(TAG, `startAbility failed errcode:${err.code}`);
            })
          })
        }
        .height(56)
        .backgroundColor($r('app.color.start_window_background'))
        .borderRadius(24)
        .margin({ top: 12, right: 12, left: 12 })

        ListItem() {
          Flex({ justifyContent: FlexAlign.SpaceBetween, alignContent: FlexAlign.Center }) {
            Text($r('app.string.start_standard_second_button'))
              .textAlign(TextAlign.Start)
              .fontWeight(FontWeight.Medium)
              .margin({ top: 17, bottom: 17, left: 12, right: 92 })
              .fontSize(16)
              .width(232)
              .height(22)
              .fontColor($r('app.color.text_color'))
          }
          .onClick(() => {
            let want: Want = {
              bundleName: 'com.samples.famodelabilitydevelop',
              abilityName: 'com.samples.famodelabilitydevelop.PageAbilityStandard',
              parameters: { page: 'pages/second' }
            };
            featureAbility.startAbility({ want: want }).then((data) => {
              Logger.info(TAG, `startAbility finish:${data}`);
            }).catch((err: BusinessError) => {
              Logger.info(TAG, `startAbility failed errcode:${err.code}`);
            })
          })
        }
        .height(56)
        .backgroundColor($r('app.color.start_window_background'))
        .borderRadius(24)
        .margin({ top: 12, right: 12, left: 12 })
        ...
      }
      .height('100%')
      .backgroundColor($r('app.color.backGrounding'))
    }
    .width('100%')
    .margin({ top: 8 })
    .backgroundColor($r('app.color.backGrounding'))
  }
}

目标端PageAbility的onCreate生命周期回调中通过featureAbility的getWant方法获取want，并对参数进行解析，实现指定页面拉起：

import featureAbility from '@ohos.ability.featureAbility';
import router from '@ohos.router';

class PageAbilityStandard {
  onCreate() {
    featureAbility.getWant().then((want) => {
      if (want.parameters) {
        if (want.parameters.page) {
          router.pushUrl({ url: want.parameters.page as string });
        }
      }
    })
  }
}

export default new PageAbilityStandard();

✏️ 持续更新中……

# harmonyos # 学习 # 华为 # 鸿蒙 # 鸿蒙系统 # ui
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