javascript - 实例化Injectable类时未调用ngOnInit(ngOnInit not being called when Injectable class is Instantiated)

Question

Why isn't ngOnInit() called when an Injectable class is resolved?

(解析Injectable类时，为什么不ngOnInit() ？)

Code

(码)

import {Injectable, OnInit} from 'angular2/core';
import { RestApiService, RestRequest } from './rest-api.service';

@Injectable()
export class MovieDbService implements OnInit {

    constructor(private _movieDbRest: RestApiService){
        window.console.log('FROM constructor()');
    }

    ngOnInit() {
         window.console.log('FROM ngOnInit()');
    }

}

Console Output

(控制台输出)

FROM constructor()

  ask by Levi Fuller translate from so

Answer 1

Lifecycle hooks , like OnInit() work with Directives and Components.

(生命周期挂钩 （例如OnInit()与指令和组件一起使用。)

They do not work with other types, like a service in your case.

(它们不适用于其他类型，例如您所需要的服务。)

From docs:

(从文档：)

A Component has a lifecycle managed by Angular itself.

(组件的生命周期由Angular本身管理。)

Angular creates it, renders it, creates and renders its children, checks it when its data-bound properties change and destroy it before removing it from the DOM.

(Angular会创建，渲染，创建和渲染其子级，在其数据绑定属性更改时对其进行检查，并在将其从DOM中删除之前销毁它。)

Directive and component instances have a lifecycle as Angular creates, updates, and destroys them.

(指令实例和组件实例具有生命周期，因为Angular创建，更新和销毁它们。)