如何在ASP.NET应用程序中只加载一次数据表中的静态数据

public static class StaticDataLoader
{
    public static List<Country> Countries { get; private set; }

    static StaticDataLoader()
    {
        // 假设有一个Country类和一个数据库上下文DbEntities
        using (var db = new DbEntities())
        {
            Countries = db.Countries.ToList();
        }
    }
}

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMemoryCache();
        services.AddSingleton<ICountryService, CountryService>();
    }
}

public interface ICountryService
{
    List<Country> GetCountries();
}

public class CountryService : ICountryService
{
    private readonly IMemoryCache _cache;

    public CountryService(IMemoryCache cache)
    {
        _cache = cache;
    }

    public List<Country> GetCountries()
    {
        return _cache.GetOrCreate("countries", entry =>
        {
            entry.AbsoluteExpirationRelativeToNow = TimeSpan.FromDays(1);
            using (var db = new DbEntities())
            {
                return db.Countries.ToList();
            }
        });
    }
}