config.Routes.MapHttpRoute(
        name: "DefaultApi",
        routeTemplate: "api/{controller}/{id}",
        defaults: new { id = RouteParameter.Optional },
      );

order/Miles/三只松鼠干果/2袋
order/2017/1/13

 config.MapHttpAttributeRoutes();

 public static void Register(HttpConfiguration config)
    {
      // Web API 配置和服务

      // Web API 路由
      config.MapHttpAttributeRoutes();

      config.Routes.MapHttpRoute(
        name: "DefaultApi",
        routeTemplate: "api/{controller}/{id}",
        defaults: new { id = RouteParameter.Optional },
        constraints: new { id=@"\d+"}
      );
    }

 [Route("order/{UserNickName}/{ProductName}/{count}")]

  [Route("api/books")]
  [Route("api/books/{id:int}")]
  [Route("api/books")]

[Route("users/{id:int:length(1,3)}")]
public User GetUserById(int id) { ... }

public class NonZeroConstraint : IHttpRouteConstraint
{
  public bool Match(HttpRequestMessage request, IHttpRoute route, string parameterName, 
    IDictionary<string, object> values, HttpRouteDirection routeDirection)
  {
    object value;
    if (values.TryGetValue(parameterName, out value) && value != null)
    {
      long longValue;
      if (value is long)
      {
        longValue = (long)value;
        return longValue != 0;
      }

      string valueString = Convert.ToString(value, CultureInfo.InvariantCulture);
      if (Int64.TryParse(valueString, NumberStyles.Integer, 
        CultureInfo.InvariantCulture, out longValue))
      {
        return longValue != 0;
      }
    }
    return false;
  }
}

public static class WebApiConfig
{
  public static void Register(HttpConfiguration config)
  {
    var constraintResolver = new DefaultInlineConstraintResolver();
    constraintResolver.ConstraintMap.Add("nonzero", typeof(NonZeroConstraint));

    config.MapHttpAttributeRoutes(constraintResolver);
  }
}

[Route("{id:nonzero}")]
public HttpResponseMessage GetNonZero(int id) { ... }

public class BooksController : ApiController
{
  [Route("api/books/locale/{lcid:int")]
  public IEnumerable<Book> GetBooksByLocale(int lcid = 1033) { ... }
}

public class BooksController : ApiController
{
  [Route("api/books/locale/{lcid=1033}")]
  public IEnumerable<Book> GetBooksByLocale(int lcid) { ... }
}