harmony 鸿蒙Starting a Specified Page

2023-02-03
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Starting a Specified Page

When the launch type of a PageAbility is set to singleton (default), the onNewWant() callback is triggered if the PageAbility is not started for the first time. For details about the launch type, see PageAbility Launch Type. In this case, you can use the want parameter to transfer startup information. For example, if you want to start a PageAbility with a specified page, pass the pages information in parameters of want.

In app.ets or page of the caller PageAbility, use startAbility() to start the PageAbility again, with the page information passed in the uri parameter in want.

import featureAbility from '@ohos.ability.featureAbility';
import Want from '@ohos.app.ability.Want';

async function restartAbility() {
    let wantInfo: Want = {
        bundleName: "com.sample.MyApplication",
        abilityName: "EntryAbility",
        parameters: {
            page: "pages/second"
        }
    };
    featureAbility.startAbility({
        want: wantInfo
    }).then((data) => {
        console.info('restartAbility success.');
    });
}

Obtain the want parameter that contains the page information from the onNewWant() callback of the target PageAbility.

// Construct a singleton object in GlobalContext.ts.
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 { GlobalContext } from './GlobalContext';

class EntryAbility {  
  onNewWant(want: Want) { 
    GlobalContext.getContext().setObject("newWant", want);  
  }
}

export default new EntryAbility()

Obtain the want parameter that contains the page information from the custom component of the target PageAbility and process the route based on the URI.

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

@Entry
@Component
struct Index {
  @State message: string = 'Router Page'
  
  onPageShow() {
    console.info('Index onPageShow')
    let newWant = GlobalContext.getContext().getObject("newWant") as Want
    if (newWant.parameters) {
      if (newWant.parameters.page) {
        router.push({ url: newWant.parameters.page });
        GlobalContext.getContext().setObject("newWant", undefined)
      }
    }
  }

  build() {
    Row() {
      Column() {
        Text(this.message)
          .fontSize(50)
          .fontWeight(FontWeight.Bold)
      }
      .width('100%')
    }
    .height('100%')
  }
}

When a PageAbility in multiton mode is started or when the PageAbility in singleton mode is started for the first time, you can use the parameters parameter in want to transfer the pages information and use the startAbility() method to start the PageAbility. For details about the launch type, see PageAbility Launch Type. The target PageAbility can use the featureAbility.getWant() method in onCreate to obtain the want parameter, and then call router.push to start a specified page.

When a user touches the button on the page of the caller PageAbility, the startAbility() method is called to start the target PageAbility. The want parameter in startAbility() carries the specified page information.

import featureAbility from '@ohos.ability.featureAbility';
import { BusinessError } from '@ohos.base';

@Entry
@Component
struct Index {
  @State message: string = 'Hello World'

  build() {
    Row() {
      Button("startAbility")
        .onClick(() => {
          featureAbility.startAbility({
            want: {
              bundleName: "com.exm.myapplication",
              abilityName: "com.exm.myapplication.EntryAbility",
              parameters: { page: "pages/page1" }
            }
          }).then((data) => {
            console.info("startAbility finish");
          }).catch((err: BusinessError) => {
            console.info("startAbility failed errcode:" + err.code)
          })
        })
      ...
      Button("page2")
        .onClick(() => {
          featureAbility.startAbility({
            want: {
              bundleName: "com.exm.myapplication",
              abilityName: "com.exm.myapplication.EntryAbility",
              parameters: { page: "pages/page2" }
            }
          }).then((data) => {
            console.info("startAbility finish");
          }).catch((err: BusinessError) => {
            console.info("startAbility failed errcode:" + err.code)
          })
        })
      ...
    }
    ...
  }
}

In the onCreate() callback of the target PageAbility, use the featureAbility.getWant() method to obtain the want parameter, parse the parameter, and start the specified page.

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

class EntryAbility {
  onCreate() {
    featureAbility.getWant().then((want) => {
      if (want.parameters) {
        if (want.parameters.page) {
          router.push({
            url: want.parameters.page as string
          })
        }
      }
    })
  }
  onDestroy() {
    // ...
  }
}

export default new EntryAbility()