Angular在加载动态组件需要在@NgModule的entryComponents声明组件。否则会报类似以下的错误：
DialogComponent.html:51 ERROR Error: No component factory found for DialogComponent. Did you add it to @NgModule.entryComponents?
at noComponentFactoryError (core.es5.js:3202)
at CodegenComponentFactoryResolver.webpackJsonp.../../../core/@angular/core.es5.js.CodegenComponentFactoryResolver.resolveComponentFactory (core.es5.js:3267)
at PortalHostDirective.webpackJsonp.../../../cdk/esm5/portal.es5.js.PortalHostDirective.attachComponentPortal (portal.es5.js:500)
at MatDialogContainer.webpackJsonp.../../../material/esm5/dialog.es5.js.MatDialogContainer.attachComponentPortal (dialog.es5.js:136)
at MatDialog.webpackJsonp.../../../material/esm5/dialog.es5.js.MatDialog._attachDialogContent (dialog.es5.js:635)
at MatDialog.webpackJsonp.../../../material/esm5/dialog.es5.js.MatDialog.open (dialog.es5.js:538)
at MenuComponent.webpackJsonp.../../../../../src/app/menu/menu.component.ts.MenuComponent.openDialog (menu.component.ts:46)
at Object.eval [as handleEvent] (MenuComponent.html:51)
at handleEvent (core.es5.js:11998)
at callWithDebugContext (core.es5.js:13467)
在@NgModule的entryComponents声明组件：
@NgModule({
imports: [
CommonModule,
AppRoutingModule
],
entryComponents: [DialogComponent],
declarations: [DialogComponent],
providers: [AppService]
})
export class AppModule { }
在例子里DialogComponent是一个弹出框组件，动态加载。