【翻译】ASP.NET WEB API异常处理

public Product GetProduct(int id) 
{ 
    Product item = repository.Get(id); 
    if (item == null) 
    { 
        throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.NotFound)); 
    } 
    return item; 
}

public Product GetProduct(int id) 
{ 
    Product item = repository.Get(id); 
    if (item == null) 
    { 
        var resp = new HttpResponseMessage(HttpStatusCode.NotFound) 
        { 
            Content = new StringContent(string.Format("No product with ID = {0}", id)), 
            ReasonPhrase = "Product ID Not Found" 
        } 
        throw new HttpResponseException(resp); 
    } 
    return item; 
}

 using System; 
    using System.Net; 
    using System.Net.Http; 
    using System.Web.Http.Filters; 
 
    public class NotImplExceptionFilter : ExceptionFilterAttribute  
    { 
        public override void OnException(HttpActionExecutedContext context) 
        { 
            if (context.Exception is NotImplementedException) 
            { 
                context.Response = new HttpResponseMessage(HttpStatusCode.NotImplemented); 
            } 
        } 
    } 

    public class WebApiApplication : System.Web.HttpApplication
    {
        static void ConfigureApi(HttpConfiguration config)
        {
            config.Filters.Add(new HelloWebAPI.Controllers.NotImplExceptionFilter());
        } 
        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();

            ConfigureApi(GlobalConfiguration.Configuration);
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);
        }
    }

        [NotImplExceptionFilter]
        public IEnumerable<Product> AllProducts()
        {