这就是我的工作原理:

public class LanguageMessageHandler : DelegatingHandler
{
    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        // here you can chose to get the lang from database, cookie or from the request if the culture is stored on local storage.
        SetCulture(request, "ro-RO");
        return base.SendAsync(request, cancellationToken);
    }

    private void SetCulture(HttpRequestMessage request, string lang)
    {
        request.Headers.AcceptLanguage.Clear();
        request.Headers.AcceptLanguage.Add(new StringWithQualityHeaderValue(lang));
        Thread.CurrentThread.CurrentCulture = new CultureInfo(lang);
        Thread.CurrentThread.CurrentUICulture = new CultureInfo(lang);
    }
}

将LanguageMessageHandler添加到WebApiConfig中的MessageHandler

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        config.MessageHandlers.Add(new LanguageMessageHandler()); // <- add this line
        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );
    }
}