webapi filter 全局　及　只返回json格式

在webapi中定义全局的过滤器要在app_start下WebApiConfig.cs中

public static class WebApiConfig
{
public static void Register(HttpConfiguration config)
{
config.MapHttpAttributeRoutes();
config.Routes.MapHttpRoute(
name: "push.api.v1",
routeTemplate: "v1/{controller}/{id}",
defaults: new { id = RouteParameter.Optional }
);

config.Filters.Add(new PushFilter());

// Remove the JSON formatter
            //config.Formatters.Remove(config.Formatters.JsonFormatter);

            // Remove the XML formatter
            config.Formatters.Remove(config.Formatters.XmlFormatter);

}
}

在mvc中要在Global.asax中

protected void Application_Start()
{
AreaRegistration.RegisterAllAreas();
GlobalFilters.Filters.Add(new DemoActionAttributeFilter() { Message = "Gloable" });
RegisterGlobalFilters(GlobalFilters.Filters);

RegisterRoutes(RouteTable.Routes);
}

原文：http://www.cnblogs.com/zhangxiaoshuai/p/5667726.html