1. 在Angular应用中创建一个AuthGuard服务，该服务会检查用户是否已登录并授权访问受保护的路由。

import { Injectable } from '@angular/core';
import { CanActivate, ActivatedRouteSnapshot, RouterStateSnapshot, UrlTree, Router } from '@angular/router';
import { Observable } from 'rxjs';
import { AuthService } from './auth.service';

@Injectable({
  providedIn: 'root'
})
export class AuthGuard implements CanActivate {

  constructor(private authService: AuthService, private router: Router) {}

  canActivate(
    next: ActivatedRouteSnapshot,
    state: RouterStateSnapshot): Observable | Promise | boolean | UrlTree {
    if (this.authService.isAuthenticated()) {
      return true;
    }
    // If not authenticated, redirect to login page
    this.router.navigate(['/login']);
    return false;
  }

}

2. 在应用中设置路由保护，当用户尝试访问受保护的路由时会触发AuthGuard服务中的canActivate方法。例如，以下代码演示了如何保护具有“/dashboard”路径的路由。

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
import { AuthGuard } from './auth.guard';
import { DashboardComponent } from './dashboard/dashboard.component';

const routes: Routes = [
  { path: '', redirectTo: '/dashboard', pathMatch: 'full' },
  { path: 'login', component: LoginComponent },
  { path: 'dashboard', component: DashboardComponent, canActivate: [AuthGuard] },
];

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

3. 在ASP.NET Core应用中实现基于JWT的身份验证，可以使用ASP.NET Core身份验证和授权组件或第三方库（如IdentityServer）来实现。以下示例演示了如何在ASP.NET Core中使用JwtBearer中间件实现身份验证。

using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;

[