Angular 2依赖注入不起作用

Question

我在angular 2上编写了一个应用程序，我想缓存一些数据。 当您转到每个页面时，我会不断地致电服务设计人员，而不是传递现有对象。

1. 组件1：

    import { Component, OnInit } from '@angular/core'; import { DataService } from '../services/globaldata.service' import { User } from '../models/User'; @Component({ selector: 'Campaigns', templateUrl: './campaigns.component.html', providers: [DataService] }) export class CampaignComponent implements OnInit { public user: User; constructor(private dataService: DataService) { this.user = dataService.getData(); } ngOnInit() { this.user = this.dataService.getData(); } } 

2. 组件2：

    import { Component, OnInit } from '@angular/core'; import { DataService } from '../services/globaldata.service' import { User } from '../models/User'; @Component({ selector: 'Wallet', templateUrl: './wallet.component.html', providers: [DataService] }) export class WalletComponent implements OnInit { public user: User; constructor(private dataService: DataService) { this.user = dataService.getData(); } ngOnInit() { this.user = this.dataService.getData(); } } 

3. 服务：

    import { User } from '../models/user'; export class DataService { private data: User; getData(): User { return this.data; } setData( price: number) { this.data = new User(price); } constructor() { this.data = new User(this.randomInteger(1,1000)); } public randomInteger(min:number, max:number) { var rand = min - 0.5 + Math.random() * (max - min + 1) rand = Math.round(rand); console.log(rand); return rand; } 

控制台每次导航时都会生成一个随机值，但是我认为依赖项注入应该缓存该值。 可能是什么错误？

Answer 1

您的服务缺少@Injectable() ：

它看起来应该像这样：

@Injectable()
export class DataService
{ ... }