angular2 – ngOnInit在可注入类被实例化时不被调用

发布时间：2020-12-17 08:45:22 所属栏目：安全来源：网络整理

导读：为什么在解析Injectable类时调用ngOnInit()？码 import {Injectable,OnInit} from 'angular2/core';import { RestApiService,RestRequest } from './rest-api.service';@Injectable()export class MovieDbService implements OnInit { constructor(private

为什么在解析Injectable类时调用ngOnInit()？

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()');
    }

}

控制台输出

FROM constructor()

Lifecycle hooks，像OnInit()与指令和组件一起工作。他们不与其他类型，如在您的情况下的服务工作。来自文档：

A Component has a lifecycle managed by Angular itself. Angular creates it,renders it,creates and renders its children,checks it when its data-bound properties change,and destroys it before removing it from the DOM.

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

（编辑：李大同）

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