在webAPI的BaseController上使用RoutePrefix

　　在webAPI2.2中有支持，參考地址：https://docs.microsoft.com/en-us/aspnet/web-api/overview/releases/whats-new-in-aspnet-web-api-22#ARI，具體作法：

public class BaseController : ApiController
{
	[Route("{id:int}")]
	public string Get(int id)
	{
		return "Success:" + id;
	}
}
[RoutePrefix("api/values")]
public class ValuesController : BaseController
{
}

public class CustomDirectRouteProvider : DefaultDirectRouteProvider
{
	protected override IReadOnlyList<IDirectRouteFactory> 
	GetActionRouteFactories(HttpActionDescriptor actionDescriptor)
	{
		return actionDescriptor.GetCustomAttributes<IDirectRouteFactory>
		(inherit: true);
	}
}

///WebApiConfig.cs中加上這個配置

config.MapHttpAttributeRoutes(new CustomDirectRouteProvider());