C# ashx + ajax post 接受

$.ajax({
        url: "ContentPage/Set.ashx?Time=" + new Date().getTime() + "&_AactionNamed=" + strActionName + "&_UserId=" + _tmpUserId + "",
        data: { "ChannelSets": JSON.stringify(userChannels)},
        cache: false,
        type: "post",
        dataType: "json",
        contentType: 'application/json',
        success: function (data) {
            if (data != "") {
               
            }
        },
        error: function () {
     
        }
    });

    /// <summary>
    /// 创建
    /// </summary>
    /// <param name="user"></param>
    /// <param name="context"></param>
    public void Create( HttpContext context)
    {

        var input= new  Logistics.Beo.System.UspsOrderCancelChannelAddDto();
        input.UserId=Logistics.Utils.CustomResponse.GetIntResponseArg("_UserId");
        using (var reader = new StreamReader(context.Request.InputStream, Encoding.UTF8))
        {
            var objJson2 = reader.ReadToEnd();

            var objJson3 = System.Web.HttpUtility.UrlDecode(objJson2).Replace("ChannelSets=","");

            var oj33= Logistics.Utils.NewtonsoftHelper.ToObject<List<Logistics.Beo.System.UspsOrderCancelChannelDto>>(objJson3);

        
        }

　　　　　　context.Response.Write("");
　　　　　　context.Response.End();

}