public class RequireAuthorizeAttribute : AuthorizeAttribute
    {
        public override void OnAuthorization(System.Web.Http.Controllers.HttpActionContext actionContext)
        {
            if (actionContext.Request.Method == HttpMethod.Post)
            {
                HttpContent content = actionContext.Request.Content;
                
                //执行该句，会将action的参数实体置为空
                Task<JObject> task = content.ReadAsAsync<JObject>();
                var result = task.Result;

            }
        }
    }

Action如下:

  public class TestController : ApiController
    {
        [RequireAuthorize] //加上该过滤器，参数info变成了null
        [HttpPost]
        public string GetResult(UserInfo info)
        {
            return info.Name;
        }
    }

    [Serializable]
    public class UserInfo
    {
        public int ID { get; set; }
        public string Name { get; set; }
    }

前台调用：

$("#testbtn").click(function () {
　　var parm = { ID: 1, Name: "Jone" };

　　$.post("api/test/GetResult", parm, function (data) {
　　　　alert(data);
　　}, "text");
})