我的URL在angular 4中没有正确重定向

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';

const routes: Routes = [
  { path: '', redirectTo: '/home', pathMatch: 'full' }, // 重定向到'/home'
  { path: 'home', component: HomeComponent },
  { path: 'about', component: AboutComponent },
  { path: '**', component: NotFoundComponent } // 404页面
];

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }

<!-- app.component.html -->
<router-outlet></router-outlet>

// app.module.ts
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { AppRoutingModule } from './app-routing.module';

import { AppComponent } from './app.component';
import { HomeComponent } from './home.component';
import { AboutComponent } from './about.component';
import { NotFoundComponent } from './not-found.component';

@NgModule({
  declarations: [
    AppComponent,
    HomeComponent,
    AboutComponent,
    NotFoundComponent
  ],
  imports: [
    BrowserModule,
    AppRoutingModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }