Angular 创建Observable 两种方式

1.Angular 2 RxJS Subject 应用

message.service.ts

import { Injectable } from '@angular/core';
import {Observable} from 'rxjs/Observable';
import { Subject } from 'rxjs/Subject';

@Injectable()
export class MessageService {
    private subject = new Subject<any>();

    sendMessage(message: string) {
        this.subject.next({ text: message });
    }

    clearMessage() {
        this.subject.next();
    }

    getMessage(): Observable<any> {
        return this.subject.asObservable();
    }
}

home.component.ts

import { Component } from '@angular/core';
import { MessageService } from '../_services/index';

@Component({
    moduleId: module.id,
    templateUrl: 'home.component.html'
})

export class HomeComponent {
    constructor(private messageService: MessageService) {}
    
    sendMessage(): void { // 发送消息
        this.messageService.sendMessage('Message from Home Component to App Component!');
    }

    clearMessage(): void { // 清除消息
        this.messageService.clearMessage();
    }
}

app.component.ts

import { Component, OnDestroy } from '@angular/core';
import { Subscription } from 'rxjs/Subscription';

import { MessageService } from './_services/index';

@Component({
    moduleId: module.id,
    selector: 'app',
    templateUrl: 'app.component.html'
})

export class AppComponent implements OnDestroy {
    message: any;
    subscription: Subscription;

    constructor(private messageService: MessageService) {
        this.subscription = this.messageService.getMessage()
              .subscribe(message => { this.message = message; });
    }

    ngOnDestroy() {
        this.subscription.unsubscribe();
    }
}

2. 使用BehaviorSubject

private testSubjcst = new BehaviorSubject<any>('');
private testObservable = this.testSubjcst.asObservable();

ngInit(){
  this.testSubjcst.next('1,2,2,3,4,5,5,6,47');
    this.testObservable.subscribe(next => {
      console.log(next);
    });
}