如何在IONIC 2中實現觀察者模式

Question

我想在IONIC 2中實現觀察者模式。

我有這項服務

import { Injectable } from '@angular/core';
import { Http } from '@angular/http';
import { Events } from 'ionic-angular';

@Injectable()
export class ExampleService {
  private _events: Events;

  constructor(public http: Http, events: Events) {
    this._events = events;
  }

  doStuff() {
    this.raiseBeginDownloadData('data');
  }

  private raiseBeginDownloadData(hash: string){
    this._events.publish('begin-download', hash);
  }
}

這是我的控制器：

import { Component } from '@angular/core';
import { NavController, AlertController, Platform } from 'ionic-angular';
import { ExampleService } from '../../providers/example-service';

@Component({
  selector: 'page-exaple',
  templateUrl: 'example.html',
  providers: [ExampleService]
})

export class MyPage {

  constructor(public navCtrl: NavController, platform: Platform, public alertCtrl: AlertController, public eventSvc: ExampleService) {

  }

}

我的問題是，在這種情況下如何實現觀察者模式？

我知道在我的服務中，我需要創建一種方法，以使控制器可以訂閱/取消訂閱該事件； 並且在控制器中，我需要創建一個notify方法，但是我不知道如何使用IONIC 2 / RxJs實現

非常感謝！

Answer 1

事件是一種發布-訂閱樣式的事件系統，用於在您的應用程序中發送和響應應用程序級事件。

因此，您可以在service發出它並訂閱Component 。

import { Events } from 'ionic-angular';

constructor(public events: Events) {}

// first page (publish an event when a user is created)
function createUser(user) {
  console.log('User created!')
  events.publish('user:created', user, Date.now());
}

// second page (listen for the user created event)
events.subscribe('user:created', (user, time) => {
  // user and time are the same arguments passed in `events.publish(user, time)`
  console.log('Welcome', user, 'at', time);
});

就你而言。

export class MyPage {

  constructor( public events: Events) { }
  this.events.subscribe('begin-download', (user, time) => {
    // user and time are the same arguments passed in `events.publish(user, time)`
    console.log('Welcome', user, 'at', time);
  });
}