Redirecting to a UIAbility Through the router Event

The router capability of the postCardAction API can be used in a widget to quickly start a specific UIAbility of the widget provider. By leveraging this capability, an application can provide in the widget multiple buttons, each of which targets a different target UIAbility. For example, a camera widget can provide the buttons that redirect the user to the UIAbility for taking a photo and the UIAbility for recording a video.

WidgerCameraCard

NOTE

This topic describes development for dynamic widgets. For static widgets, see FormLink.

Generally, a button is used to start a page. Below is an example:

Design two buttons on the widget page. When one of the buttons is clicked, postCardAction is called to send a router event to the specified UIAbility, with the content to be transferred defined in the event.

@Entry
@Component
struct WidgetCard {
  build() {
    Column() {
      Button ('Function A')
        .margin('20%')
        .onClick(() => {
          console.info('Jump to EntryAbility funA');
          postCardAction(this, {
            'action': 'router',
            'abilityName': 'EntryAbility', // Only the UIAbility of the current application is allowed.
            'params': {
              'targetPage': 'funA' // Process the information in the EntryAbility.
            }
          });
        })

      Button ('Function B')
        .margin('20%')
        .onClick(() => {
          console.info('Jump to EntryAbility funB');
          postCardAction(this, {
            'action': 'router',
            'abilityName': 'EntryAbility', // Only the UIAbility of the current application is allowed.
            'params': {
              'targetPage': 'funB' // Process the information in the EntryAbility.
            }
          });
        })
    }
    .width('100%')
    .height('100%')
  }
}

The UIAbility receives the router event and obtains parameters. It then starts the page specified by params.

import UIAbility from '@ohos.app.ability.UIAbility';
import window from '@ohos.window';
import Want from '@ohos.app.ability.Want';
import Base from '@ohos.base';
import AbilityConstant from '@ohos.app.ability.AbilityConstant';

let selectPage: string = "";
let currentWindowStage: window.WindowStage|null = null;

export default class EntryAbility extends UIAbility {
  // If the UIAbility is started for the first time, the onCreate lifecycle callback is triggered after the router event is received.
  onCreate(want: Want, launchParam: AbilityConstant.LaunchParam) {
    // Obtain the targetPage parameter passed in the router event.
    console.info("onCreate want:" + JSON.stringify(want));
    if (want.parameters?.params !== undefined) {
      let params: Record<string, string> = JSON.parse(JSON.stringify(want.parameters?.params));
      console.info("onCreate router targetPage:" + params.targetPage);
      selectPage = params.targetPage;
    }
  }
  // If the UIAbility is running in the background, the onNewWant lifecycle callback is triggered after the router event is received.
  onNewWant(want: Want, launchParam: AbilityConstant.LaunchParam) {
    console.info("onNewWant want:" + JSON.stringify(want));
    if (want.parameters?.params !== undefined) {
      let params: Record<string, string> = JSON.parse(JSON.stringify(want.parameters?.params));
      console.info("onNewWant router targetPage:" + params.targetPage);
      selectPage = params.targetPage;
    }
    if (currentWindowStage != null) {
      this.onWindowStageCreate(currentWindowStage);
    }
  }

  onWindowStageCreate(windowStage: window.WindowStage) {
    let targetPage: string;
    // Start the page specified by targetPage.
    switch (selectPage) {
      case 'funA':
        targetPage = 'pages/FunA';
        break;
      case 'funB':
        targetPage = 'pages/FunB';
        break;
      default:
        targetPage = 'pages/Index';
    }
    if (currentWindowStage === null) {
      currentWindowStage = windowStage;
    }
    windowStage.loadContent(targetPage, (err: Base.BusinessError) => {
      if (err && err.code) {
        console.info('Failed to load the content. Cause: %{public}s', JSON.stringify(err));
        return;
      }
    });
  }
};