jquery ajax 分页

<script src="../Js/jQuery/jquery-1.8.2.min.js" type="text/javascript"></script>
<script type="text/javascript">

        $(document).ready(function() {
            $("#pages").val(Math.ceil(50 / 10));
        });
        //翻页
        function changePage(ctype) {
            switch (ctype) {
                case 'first':
                    $("#page").val(1);
                    break;
                case 'prev':
                    if ($("#page").val() > 1) {
                        var num = parseInt($("#page").val()) - 1;
                        $("#page").val(num);
                    }
                    break;
                case 'next':
                    if ($("#page").val() < $("#pages").val()) {
                        var num = parseInt($("#page").val()) + 1;
                        $("#page").val(num);
                    }
                    break;
                case 'last':
                    $("#page").val($("#pages").val());
                    break;
            }
//            if ($("#newp").val() == $("#page").val())
//                return false;
            populate();
        }

          //获取数据
        function populate() {

            if ($("#page").val() > $("#pages").val())
                $("#page").val($("#pages").val());

            var param = [
                      { name: 'page', value: $("#page").val() }
                    , { name: 'rp', value: 10 }
                    , { name: 'sortname', value: "" }
                    , { name: 'sortorder', value: "" }
                    , { name: 'query', value: "" }
                    , { name: 'qtype', value: "" }
                    , { name: 'primaryKey', value: "" }
                ];
            $.ajax({
                type: "POST",
                url: "HandlerPager.ashx?Action=Pagers",
                async: true,
                data: param,
                dataType: "json",
                success: function(data) {
                    $("#spanPageIndex").html(data);
                },
                error: function(data) {
                    try {
                    } catch (e) { }
                }
            });
        }
    </script>

<div>
            <input type="hidden" value="1" id="page" /><!--当前页-->
            <input type="hidden" value="1"id="pages" /><!--总页数-->

            <span id="first" onclick="changePage(this.id)">首页</span>
            <span id="prev" onclick="changePage(this.id)">上一页</span>
            <span id="spanPageIndex" >1</span>
            <span id="next" onclick="changePage(this.id)">下一页</span>
            <span id="last" onclick="changePage(this.id)">尾页</span>
        </div>

 public class HandlerPager : IHttpHandler
    {

        private string requestParam = string.Empty;//HttpHandler用于异步调用提交的服务器类
        public void ProcessRequest(HttpContext context)
        {
              requestParam = context.Request.QueryString["Action"];

              switch (requestParam)
              {
                  case "Pagers":        //ﾨ
                      Pagers(context);
                      break;
              } 

        }

        void Pagers(HttpContext context)
        {
            string result = string.Empty;
            Model_Wzsjfycs parm = FlexiGridParm.GetFlexiGridParam(context);
            result = parm.PageIndex.ToString();
            context.Response.ContentType = "text/plain";
            context.Response.Write(result);
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }

    /// <summary>
    /// 分页请求参数类  可有可无，为了方便获取数据
    /// </summary>
    public class Model_Wzsjfycs
    {
        /// <summary>
        /// 当前页码
        /// </summary>
        public int PageIndex;
        /// <summary>
        ///
        /// </summary>
        public int PageSize;
        /// <summary>
        /// 主键
        /// </summary>
        public string PrimaryKey;
        /// <summary>
        /// 排序字段(多个字段用','号分开)
        /// </summary>
        public string OrderFields;
        /// <summary>
        /// 排序方式（asc 、desc）
        /// </summary>
        public string Order;
        /// <summary>
        /// 查询字段
        /// </summary>
        public string FilterFields;
        /// <summary>
        /// 查询内容
        /// </summary>
        public string FilterContents;
    }

 public class FlexiGridParm
    {

        /// <summary>
        /// 从HTTP中提取请求并封装FlexiGridParm类 用于解析 HttpContent请求上下文对象(页面发送请求的数据 以及 请求后返回的数据 );
        /// </summary>
        /// <param name="context">HttpContext</param>
        /// <returns>Model_PagingParm</returns>
        public static Model_Wzsjfycs GetFlexiGridParam(HttpContext context)
        {
            string pageIndex = context.Request["page"],
                   pageSize = context.Request["rp"],
                   primaryKey = context.Request["primaryKey"],
                   orderFields = context.Request["sortname"],
                   order = context.Request["sortorder"],
                   filterFields = context.Request["qtype"],
                   filterContents = context.Request["query"];

            Model_Wzsjfycs parm = new Model_Wzsjfycs();
            //当前页码
            if (!string.IsNullOrEmpty(pageIndex))
                parm.PageIndex = int.Parse(pageIndex);
            else
                parm.PageIndex = ;
            //一页显示条数
            if (!string.IsNullOrEmpty(pageSize))
                parm.PageSize = int.Parse(pageSize);
            else
                parm.PageSize = ;
            //主键
            if (!string.IsNullOrEmpty(primaryKey))
                parm.PrimaryKey = primaryKey;
            else
                parm.PrimaryKey = string.Empty;
            //排序
            if (!string.IsNullOrEmpty(orderFields))
                parm.OrderFields = orderFields.Trim();
            else
                parm.OrderFields = string.Empty;
            //排序字段
            if (!string.IsNullOrEmpty(order) && order.ToLower() == "desc")
                parm.Order = "desc";
            else
                parm.Order = "asc";
            //查询字段
            if (!string.IsNullOrEmpty(filterFields) && filterContents != null)
            {
                parm.FilterFields = filterFields;
                parm.FilterContents = context.Server.UrlDecode(filterContents);
            }
            else
                parm.FilterFields = parm.FilterContents = string.Empty;

            return parm;
        }

        /// <summary>
        /// 获取FlexiGridParm 对象
        /// </summary>
        /// <param name="pageIndex">当前页码</param>
        /// <param name="pageSize">一页显示条数</param>
        /// <param name="primaryKey">主键</param>
        /// <param name="orderFields">排序字段（多个用','号隔开）</param>
        /// <param name="order">排序方式（asc、desc）</param>
        /// <param name="filterFields">查询字段</param>
        /// <param name="filterContents">查询内容</param>
        /// <returns>Model_PagingParm</returns>
        public static Model_Wzsjfycs GetFlexiGridParam(int pageIndex, int pageSize, string primaryKey, string orderFields, string order, string filterFields, string filterContents)
        {
            Model_Wzsjfycs parm = new Model_Wzsjfycs();
            parm.PageIndex = pageIndex;
            parm.PageSize = pageSize;
            parm.PrimaryKey = primaryKey;
            parm.OrderFields = orderFields;
            parm.Order = order;
            parm.FilterFields = filterFields;
            parm.FilterContents = filterContents;
            return parm;
        }

    }