angular subrouting

const routes: Routes = [
  {
    path: '',
    redirectTo: '/home',
    pathMatch: ' full '
  },
  {
    path: 'home',
    component: HomeComponent
  },
  {
    path: 'product/:id',
    component: ProductComponent,
    children: [
      { path: '', component: ProductDescComponent },
      { path: 'seller/:id', component: SellerInfoComponent }
    ]
  }
  ,
  {
    path: '**',
    component: Code404Component
  }
];

<p>
  product works!
</p>
<p>商品Id{{productId}}</p>
<a [routerLink]= " ['./'] " >Description</a>
<a [routerLink]= " ['./seller',99] "> Seller Information</a>
<router-outlet></router-outlet>

import { Component, OnInit } from '@angular/core';
import { ActivatedRoute } from '@angular/router';

@Component({
  selector: 'app-seller-info',
  templateUrl: './seller-info.component.html',
  styleUrls: ['./seller-info.component.css']
})
export class SellerInfoComponent implements OnInit {
  private sellerId: number;

  constructor(private routeInfo: ActivatedRoute) { }

  by OnInit () {
    this.sellerId = this.routeInfo.snapshot.params["id"];
  }

}
<p>
  SellerId is: {{sellerId}}
</p>

<p>
  Cow X Commodities
</p>