首先，在 app.module.ts 文件中导入 RouterModule 和 scrollPositionRestoration，然后将 RouterModule.forRoot() 中的 scrollPositionRestoration 属性设置为 enabled。如下所示：

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

import { AppComponent } from './app.component';
import { HomeComponent } from './home/home.component';
import { AboutComponent } from './about/about.component';
import { ContactComponent } from './contact/contact.component';

const appRoutes: Routes = [
  { path: '', component: HomeComponent },
  { path: 'about', component: AboutComponent },
  { path: 'contact', component: ContactComponent }
];

@NgModule({
  declarations: [
    AppComponent,
    HomeComponent,
    AboutComponent,
    ContactComponent
  ],
  imports: [
    BrowserModule,
    RouterModule.forRoot(
      appRoutes,
      { scrollPositionRestoration: 'enabled' }
    )
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

然后，在每个组件的 ngOnInit() 方法中，通过 Inject 操作符注入窗口对象、ActivatedRoute 对象和 Router 对象，实现对滚动位置的设置和恢复。如下所示：

import { Component, Inject, OnInit } from '@angular/core';
import { ActivatedRoute, Router } from '@angular/router';
import { DOCUMENT } from '@angular/common';

@Component({
  selector: 'app-home',
  templateUrl: './home.component.html',
  styleUrls: ['./home.component.css']
})
export class HomeComponent implements OnInit {

  constructor(
    @Inject(DOCUMENT) private document: Document,
    private route: ActivatedRoute,
    private router: Router
  ) { }

  ngOnInit() {
    this.route.fragment.subscribe(hash => {
      if (hash) {
        const element = this.document.querySelector(`#${hash}`);
        if (element) {
          element.scrollIntoView();
        }
      } else {
        this.router.navigate([], {
          fragment: 'top',
          replaceUrl: true,
          queryParamsHandling: 'preserve',
        });
      }
    });
  }

}

在上述代码中，首先通过 Inject 操作符注入了一个名为 DOCUMENT 的变量，