延迟加载示例

延迟加载模块可以帮助我们缩短启动时间。使用延迟加载，我们的应用程序不需要一次加载所有内容，它只需要加载用户在应用程序首次加载时期望看到的内容。只有当用户导航到他们的路线时，才会加载延迟加载的模块。

应用程序/ app.module.ts

import { NgModule } from '@angular/core';
import { BrowserModule  } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import { EagerComponent } from './eager.component';
import { routing } from './app.routing';
@NgModule({
  imports: [
    BrowserModule,
    routing
  ],
  declarations: [
    AppComponent,
    EagerComponent
  ],
  bootstrap: [AppComponent]
})
export class AppModule {}

应用程序/ app.component.ts

import { Component } from '@angular/core';
@Component({
  selector: 'my-app',
  template: `<h1>My App</h1>    <nav>
      <a routerLink="eager">Eager</a>
      <a routerLink="lazy">Lazy</a>
    </nav>
    <router-outlet></router-outlet>
  `
})
export class AppComponent {}

应用程序/ app.routing.ts

import { ModuleWithProviders } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
import { EagerComponent } from './eager.component';
const routes: Routes = [
  { path: '', redirectTo: 'eager', pathMatch: 'full' },
  { path: 'eager', component: EagerComponent },
  { path: 'lazy', loadChildren: './lazy.module' }
];
export const routing: ModuleWithProviders = RouterModule.forRoot(routes);

应用程序/ eager.component.ts

import { Component } from '@angular/core';
@Component({
  template: '`<p>Eager Component</p>`'
})
export class EagerComponent {}

LazyModule 没有什么特别之处，除了它有自己的路由和一个名为 LazyComponent 的组件（但没有必要为你的模块命名或 simliar）。

应用程序/ lazy.module.ts

import { NgModule } from '@angular/core';
import { LazyComponent }   from './lazy.component';
import { routing } from './lazy.routing';
@NgModule({
  imports: [routing],
  declarations: [LazyComponent]
})
export class LazyModule {}

应用程序/ lazy.routing.ts

import { ModuleWithProviders } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
import { LazyComponent } from './lazy.component';
const routes: Routes = [
  { path: '', component: LazyComponent }
];
export const routing: ModuleWithProviders = RouterModule.forChild(routes);

应用程序/ lazy.component.ts

import { Component } from '@angular/core';
@Component({
  template: `<p>Lazy Component</p>`
})
export class LazyComponent {}