Angular2 - Starter - NgModule

当你安装完成Ng2开发环境时，你可能从NgModule开始去写一个Ng2的app，一个Angular2的应用，一般通过一个NgModule来启动，而在NgModule中需要定义root component,申明sub component，sub modules，providers等.

1.导入基本模块

1 import { NgModule, ApplicationRef,Pipe } from '@angular/core';
2 import { BrowserModule } from '@angular/platform-browser';
3 import { FormsModule } from '@angular/forms';
4 import { HttpModule } from '@angular/http';
5 import { TailNumberPipeModule } from './components/extensions/pipes/tail-number-only/tail-number-length.module';
6 import { RouterModule, PreloadAllModules } from '@angular/router';
7 import { ROUTES } from './app.routes';

2.导入应用模块

// AppComponent is our top level component
import { AppComponent } from './app.component';
import { APP_RESOLVER_PROVIDERS } from './app.resolver';
//应用级别的service
import { AppState, InternalStateType } from './app.service';
//EnvSvc是一个公共的service，它提供当前应用环境的识别，并且返回当前环境的应用服务应访问的API Server等
import { EnvSvc } from './services/environment.service';

//主要子组件
import { HomeComponent } from './components/sections/home';
import { AboutComponent } from './components/sections/about';
import { LogOnComponent } from './components/sections/logon'; import { FriendsComponent } from './components/sections/friends';

//people-finder 是用来搜索用户的一个控件
import { PeopleFinderComponent } from './components/controls/people-finder';
//AgeGroupDevider 是一个自定义指令(Directive)，根据输入的生日，划分该用户的年龄段，并改变用户信息容器的展现形式.
import { AgeGroupDevideDiretive } from './components/extensions/directives/age-group-devider';

//TailNumberPipeMudule是一个自定义模块，它提供一个通道（Pipe），可以理解为适配器，通过输入的电话号码，返回隐藏指定数量的尾号.

import { TailNumberPipeModule } from './components/extensions/pipes/tail-number-only/tail-number-length.module';

3.为了区分开Custom Directive,Sub Component,Custom Module等的引入，我们将这些模块进行分类

const APP_PROVIDERS = [
  ...APP_RESOLVER_PROVIDERS,
  AppState,
//这里申明的提供商可以注入到其他service,component,directive中
//class UserSvc{
//　　constructor(public envSvc:EnvSvc){
//　　}
//}

  EnvSvc
];

const APP_EXTENSIONS_DECLARATIONS = [
  AgeGroupDevideDiretive
];

const APP_EXTENSIONS_PIPEMODULES = [
  TailNumberPipeModule
];

const APP_CONTROLS_DECLARATIONS = [
  PeopleFinderComponent
];

const APP_MAIN_COMPONENTS = [
  AppComponent,
  LogOnComponent,
  FriendsComponent,
  ChatsComponent,
  AboutComponent,
  HomeComponent
];

4.导出一个类，并未该类增加NgModule修饰

@NgModule({
//应用根组件
  bootstrap: [ AppComponent ],
//申明主要组件，控件，自定义指令，扩展模块
  declarations: [
    ...APP_MAIN_COMPONENTS,
    ...APP_CONTROLS_DECLARATIONS,
    ...APP_PUBLIC_DIRECTIVES,
    ...APP_EXTENSIONS_DECLARATIONS
  ],
//导入基本模块和自定义模块
//导入的应是@NgModule修饰的类
  imports: [ // import modules
    BrowserModule,
    FormsModule,
    HttpModule,
    ...[APP_EXTENSIONS_PIPEMODULES],
    RouterModule.forRoot(ROUTES, { useHash: true, preloadingStrategy: PreloadAllModules })
  ],
//申明提供商，主要包括一些service
  providers: [ 
    ENV_PROVIDERS,
    ...APP_PROVIDERS
  ]
})

export class AppModule {
//在应用主模块的构造函数中注入AppState这个service
  constructor(public appRef: ApplicationRef, public appState: AppState) {}
}