UIAbility组件基本用法

本文主要介绍UIAbility组件的基本用法，包括：

指定UIAbility的启动页面。
获取UIAbility的上下文UIAbilityContext。
获取UIAbility拉起方的信息。

指定UIAbility的启动页面

应用中的UIAbility在启动过程中，需要指定启动页面，否则应用启动后会因为没有默认加载页面而导致白屏。可以在UIAbility的onWindowStageCreate()生命周期回调中，通过WindowStage对象的loadContent()方法设置启动页面。

import { UIAbility } from '@kit.AbilityKit';
import { window } from '@kit.ArkUI';
// ···

export default class EntryAbility extends UIAbility {
// ···

  onWindowStageCreate(windowStage: window.WindowStage): void {
    // Main window is created, set main page for this ability
    windowStage.loadContent('pages/Index', (err) => {
      // ···
    });
  }

// ···
}

在DevEco Studio中创建的UIAbility中，该UIAbility实例默认会加载Index页面，根据需要将Index页面路径替换为需要的页面路径即可。

获取UIAbility的上下文信息

UIAbility类拥有自身的上下文信息，该信息为UIAbilityContext类的实例，UIAbilityContext类拥有abilityInfo、currentHapModuleInfo等属性。通过UIAbilityContext可以获取UIAbility的相关配置信息，如包代码路径、Bundle名称、Ability名称和应用程序需要的环境状态等属性信息，以及可以获取操作UIAbility实例的方法（如startAbility()、connectServiceExtensionAbility()、terminateSelf()等）。

如果需要在页面中获得当前Ability的Context，需要通过调用组件的getUIContext方法获取UIContext对象，再调用UIContext对象的getHostContext方法获取当前页面关联的UIAbilityContext或ExtensionContext。

在UIAbility中可以通过this.context获取UIAbility实例的上下文信息。

import { AbilityConstant, UIAbility, Want } from '@kit.AbilityKit';
// ···

export default class EntryAbility extends UIAbility {
  onCreate(want: Want, launchParam: AbilityConstant.LaunchParam): void {
    // 获取UIAbility实例的上下文
    let context = this.context;
  }
// ···
}

在页面中获取UIAbility实例的上下文信息，包括导入依赖资源context模块和在组件中定义一个context变量两个部分。

import { common, Want } from '@kit.AbilityKit';

@Entry
@Component
struct EventHubPage {
  private context = this.getUIContext().getHostContext() as common.UIAbilityContext;

  startAbilityTest(): void {
    let want: Want = {
      // Want参数信息
      // ...
    };
    this.context.startAbility(want);
  }

  // 页面展示
  build() {
    // ...
  }
}

也可以在导入依赖资源context模块后，在具体使用UIAbilityContext前进行变量定义。

import { common, Want } from '@kit.AbilityKit';
// ...

@Entry
@Component
struct BasicUsage {
  startAbilityTest(): void {
    let context = this.getUIContext().getHostContext() as common.UIAbilityContext;
    let want: Want = {
      // Want参数信息
      // ...
    };
    context.startAbility(want);
  }

  // 页面展示
  build() {
    // ...
  }
}

当业务完成后，开发者如果想要终止当前UIAbility实例，可以通过调用terminateSelf()方法实现。

import { common, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { hilog } from '@kit.PerformanceAnalysisKit';

const DOMAIN = 0x0000;

@Entry
@Component
struct BasicUsage {
  // ...

  // 页面展示
  build() {
    Column() {
      // ...

      Button('FuncAbilityB')
        .onClick(() => {
          let context = this.getUIContext().getHostContext() as common.UIAbilityContext;
          try {
            context.terminateSelf((err: BusinessError) => {
              if (err.code) {
                // 处理业务逻辑错误
                hilog.error(DOMAIN, 'terminateSelf', `terminateSelf failed, code is ${err.code}, message is ${err.message}.`);
                return;
              }
              // 执行正常业务
              hilog.info(DOMAIN, 'terminateSelf', `terminateSelf succeed.`);
            });
          } catch (err) {
            // 捕获同步的参数错误
            let code = (err as BusinessError).code;
            let message = (err as BusinessError).message;
            hilog.error(DOMAIN, 'terminateSelf', `terminateSelf failed, code is ${code}, message is ${message}.`);
          }
        })
        // ...
    }
    // ...
  }
}

获取UIAbility拉起方的信息

拉起方（UIAbilityA）通过startAbility启动目标方（UIAbilityB）时，UIAbilityB可以通过parameters参数获取UIAbilityA的Pid、BundleName和AbilityName等信息。

通过点击UIAbilityA中的"拉起UIAbilityB"按钮，拉起UIAbilityB。

import { common, Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

@Entry
@Component
struct Index {
  @State context: common.UIAbilityContext = this.getUIContext().getHostContext() as common.UIAbilityContext;

  build() {
    List({ space: 4 }) {
      ListItem() {
        Button('terminateSelf').onClick(() => {
          this.context.terminateSelf()
        })
          .width('100%')

      }

      ListItem() {
        // 请将$r('app.string.Start_UIAbilityB')替换为实际资源文件，在本示例中该资源文件的value值为"拉起UIAbilityB"
        Button($r('app.string.Start_UIAbilityB'))
          .onClick((event: ClickEvent) => {
            let want: Want = {
              bundleName: this.context.abilityInfo.bundleName,
              abilityName: 'UIAbilityB',
            };

            this.context.startAbility(want, (err: BusinessError) => {
              if (err.code) {
                console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}.`);
              }
            });
        })
          .width('100%')
      }
    }
    .listDirection(Axis.Vertical)
    .backgroundColor(0xDCDCDC).padding(20)
    .margin({top:250})
  }
}

在UIAbilityB的onCreate生命周期中，获取UIAbilityA的Pid、BundleName和AbilityName，并通过日志输出。

import { AbilityConstant, UIAbility, Want } from '@kit.AbilityKit';
import { window } from '@kit.ArkUI';
import { hilog } from '@kit.PerformanceAnalysisKit';

const DOMAIN = 0x0000;

export default class UIAbilityB extends UIAbility {
  onCreate(want: Want, launchParam: AbilityConstant.LaunchParam): void {
    // 调用方无需手动传递parameters参数，系统会自动向Want对象中传递调用方信息。
    hilog.info(DOMAIN, 'UIAbilityB', `onCreate, callerPid: ${want.parameters?.['ohos.aafwk.param.callerPid']}.`);
    hilog.info(DOMAIN, 'UIAbilityB', `onCreate, callerBundleName: ${want.parameters?.['ohos.aafwk.param.callerBundleName']}.`);
    hilog.info(DOMAIN, 'UIAbilityB', `onCreate, callerAbilityName: ${want.parameters?.['ohos.aafwk.param.callerAbilityName']}.`);
  }

  onDestroy(): void {
    hilog.info(DOMAIN, 'UIAbilityB', `UIAbilityB onDestroy.`);
  }

  onWindowStageCreate(windowStage: window.WindowStage): void {
    hilog.info(DOMAIN, 'UIAbilityB', `Ability onWindowStageCreate.`);

    windowStage.loadContent('context/BasicUsage', (err) => {
      if (err.code) {
        hilog.error(DOMAIN, 'UIAbilityB', `Failed to load the content, error code: ${err.code}, error msg: ${err.message}.`);
        return;
      }
      hilog.info(DOMAIN, 'UIAbilityB', `Succeeded in loading the content.`);
    });
  }
}

指定UIAbility的启动页面​

获取UIAbility的上下文信息​

获取UIAbility拉起方的信息​

指定UIAbility的启动页面

获取UIAbility的上下文信息

获取UIAbility拉起方的信息