如何检索在Program.cs中返回的访问令牌，以便在Startup.cs中可用？

// Program.cs
public class Program
{
    public static void Main(string[] args)
    {
        var webHostBuilder = CreateWebHostBuilder(args);
        var host = webHostBuilder.Build();

        // 获取访问令牌
        var accessToken = GetAccessToken();

        // 注册访问令牌服务
        host.Services.AddSingleton<IAccessTokenService>(new AccessTokenService(accessToken));

        host.Run();
    }

    public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>();

    private static string GetAccessToken()
    {
        // 获取访问令牌的逻辑
        // 这可以是一个简单的方法，也可以是一个调用API或其他身份验证服务的方法
        // 假设访问令牌存储在一个名为accessToken的变量中
        var accessToken = "your-access-token";
        return accessToken;
    }
}

// Startup.cs
public class Startup
{
    private readonly IAccessTokenService _accessTokenService;

    public Startup(IAccessTokenService accessTokenService)
    {
        _accessTokenService = accessTokenService;
    }

    public void ConfigureServices(IServiceCollection services)
    {
        // 注册身份验证和授权中间件
        services.AddAuthentication()
            .AddJwtBearer(options =>
            {
                options.TokenValidationParameters = new TokenValidationParameters
                {
                    ValidateIssuer = true,
                    ValidateAudience = true,
                    ValidateLifetime = true,
                    ValidIssuer = "your-issuer",
                    ValidAudience = "your-audience",
                    IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_accessTokenService.GetAccessToken()))
                };
            });

        // 其他服务的注册
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        // 中间件的配置

        // 使用访问令牌进行身份验证的示例
        app.Use(async (context, next) =>
        {
            var accessToken = _accessTokenService.GetAccessToken();
            // 使用访问令牌进行身份验证的逻辑
            await next.Invoke();
        });

        // 其他配置
    }
}

// 访问令牌服务接口
public interface IAccessTokenService
{
    string GetAccessToken();
}

// 访问令牌服务实现
public class AccessTokenService : IAccessTokenService
{
    private readonly string _accessToken;

    public AccessTokenService(string accessToken)
    {
        _accessToken = accessToken;
    }

    public string GetAccessToken()
    {
        return _accessToken;
    }
}