jQuery DataTables 分页

HTML：==================================================================

<div class="ibox-content">
                        <div class="thead">                 
                         <input placeholder="请输入搜索内容" id="strWhere" type="text" />
                        </div>
                        <table id="userlist" class="table table-striped table-bordered table-hover">
                            <thead>
                                <tr>
                                      <th></th>
                                    <th><input type="checkbox" class="checkall" /></th>                               
                                    <th>昵称</th>
                                    <th>电话</th>
                                    <th>性别</th>
                                    <th>年龄</th>
                                    <th>注册日期</th>
                                    <th>状态</th>
                                    <th>操作</th>
                                </tr>
                            </thead>
                        </table>
                    </div>

JS:（注：我的jQuery DataTables已经汉化，此处不再配置oLanguage）=====================
$(function () {
   
    $('#userlist').DataTable({
        bProcessing: true, //DataTables载入数据时，是否显示‘进度’提示  
        bStateSave: false, //是否打开客户端状态记录功能,此功能在ajax刷新纪录的时候不会将个性化设定回复为初始化状态  
        aLengthMenu: [10,20, 40, 60, 100, 1000], //更改显示记录数选项  
        iDisplayLength: 10, //默认显示的记录数  
        bInfo: true, //是否显示页脚信息，DataTables插件左下角显示记录数  
        bPaginate: true, //是否显示（应用）分页器  
        autoWidth: true, //是否自适应宽度  
        bScrollCollapse: true, //是否开启DataTables的高度自适应，当数据条数不够分页数据条数的时候，插件高度是否随数据条数而改变  
        sPaginationType: "full_numbers", //详细分页组，可以支持直接跳转到某页  
        bSort: false, //是否启动各个字段的排序功能  
        bFilter: false, //是否启动过滤、搜索功能        
        bServerSide: true,//开启此模式后，你对datatables的每个操作 每页显示多少条记录、下一页、上一页、排序（表头）、搜索，这些都会传给服务器相应的值。
        "ajax": {
            url: "/Ajax/UserMgrAjax.ashx?cmd=userList",
            type:"POST",
            data: { "strWhere": $('#strWhere').val() }
            
        } ,
        columns: [
            {
                "sWidth": "4%",
                "sClass": "text-center",
                "data": null, "targets": 0
            },
             {
                 "sWidth": "4%",
                 "sClass": "text-center",
                 "data": "u_id",
                 "render": function (data, type, full, meta) {//这里就是要显示的checkbox多选框了
                     return '<input type="checkbox"  class="checkchild"  value="' + data + '" />';
                 },
                 "bSortable": false
             },
              
              { "sClass": "text-center", "data": "u_name" },
             { "sClass": "text-center", "data": "u_tel" },
             {
                 "sClass": "text-center",
                 "data": "u_sex",
                 "render": function (data, type, row, meta) {
                   
                     var content = "保密";
                     if (data == "1")
                         content = "男";
                     if (data == "2")
                         content = "女";
                     return content;
                 }
                 
             },
             { "sClass": "text-center", "data": "u_age" },
             { "sClass": "text-center", "data": "u_registerdate" },
             {
                 "sClass": "text-center",
                 "data": "u_state",
                 "render": function (data, type, row, meta) {
                     var content = "非正常";
                     if (data == "0")
                         content = "正常";
                     if (data == "1")
                         content = "锁定";
                     return content;
                 }
             },
             {
                 "sClass": "text-center",
                 "data": "u_registerdate",
                 render: function (data, type, row, meta) {

return "<a title='编辑' class='glyphicon glyphicon-edit nounderline' href='javascript:editTabRow();'></a>&nbsp;";
                 }
             }
             
        ],
        fnDrawCallback: function () {
            
            var startIndex = this.api().context[0]._iDisplayStart;//获取到本页开始的条数
            this.api().column(0).nodes().each(function (cell, i) {
             //翻页序号连续
             cell.innerHTML = startIndex + i + 1;

});
        }
       
    });
    $(".checkall").click(function () {
        var check = $(this).prop("checked");
        $(".checkchild").prop("checked", check);
    });

});

.ashx.cs：==================================================================
namespace SmartAdmin.Ajax
{
    /// <summary>
    /// UserMgrAjax 的摘要说明
    /// </summary>
    public class UserMgrAjax : IHttpHandler
    {
        string info = "";
        string json = "";
        bool rbool = false;
        HttpContext context;
        JavaScriptSerializer jss = new JavaScriptSerializer();
        Dictionary<string, object> dic = new Dictionary<string, object>();
        public void ProcessRequest(HttpContext context)
        {
            this.context = context;
            context.Response.ContentEncoding = Encoding.GetEncoding("utf-8");//避免出现乱码
            //接收浏览器 get/post 过来的参数cmd
            string cmd = context.Request["cmd"].ToString();
            switch (cmd)
            {
                case "userList": json = GetUserList();
                    break;
            }
            context.Response.Write(json);
        }
        /// <summary>
        /// 获得用户列表
        /// </summary>
        /// <param name="index"></param>
        /// <returns></returns>
        public string GetUserList()
        {
            #region ===代码===
            int totalCount = 0;//所有的
            int selCount = 0;//根据条件搜索到的
            string sqlSel = RequestHelper.GetQueryString("strWhere");
            List<t_user> list = UserDal.m_UserDal.GetList("");
            totalCount = list.Count;
            int draw = Common.Utils.ToInt(context.Request.Params["draw"]);
            int start = Common.Utils.ToInt(context.Request.Params["start"]);
            int length = Common.Utils.ToInt(context.Request.Params["length"]);
            list = UserDal.m_UserDal.GetList(sqlSel, length, (start / length) + 1);
            selCount = list.Count;
            dic.Add("draw", draw);
            dic.Add("recordsTotal", selCount);
            dic.Add("recordsFiltered", totalCount);
            dic.Add("data", list);
            return jss.Serialize(dic);
            #endregion ===代码===

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