JS获取Response.Write乱码~解决方案

<script language="javascript">        var httpxml;        function GetAllBook()        {            var pageIndex = document.getElementById("hfPageIndex").value;            var condition = document.getElementById("txtCondition").value;            httpxml = new ActiveXObject("Microsoft.XMLHTTP");            httpxml.open("Post","Ajax.aspx?Type=GetOrder&pageIndex="+pageIndex+"&condition="+condition);            httpxml.onreadystatechange = OnMessageBack;            httpxml.send(null);        }                function OnMessageBack()        {            if(httpxml.readystate == 4 && httpxml.status == 200)            {                if (httpxml.responsetext !="")                {                    var tab = document.getElementById("tabOrder");                    AddRows(tab,20 ,5,httpxml.responsetext);                }            }        }    </script>

namespace Reader{    public partial class Ajax : System.Web.UI.Page    {        protected void Page_Load(object sender, EventArgs e)        {            if (Request.QueryString["Type"] != null)            {                string type = Request.QueryString["Type"].Trim();                if (type.Equals("GetOrder"))                {                    int index = int.Parse(Request.QueryString["pageIndex"].Trim());                    string condition = Request.QueryString["condition"].Trim();                    string sql = "";                    if (condition == "")                    {                        sql = string.Format("SELECT * FROM BookInfo ORDER BY bookName ASC LIMIT {0},100;", (index - 1) * 100);                    }                    else                    {                        sql = string.Format("SELECT * FROM BookInfo WHERE bookName = '{0}' ORDER BY bookName ASC;", condition);                    }                    string returnString = "";                    DataTable dt = MySQL.GetDataSet(sql).Tables[0];                    foreach (DataRow row in dt.Rows)                    {                        returnString += row["bookName"].ToString().Trim() + "□";                        //returnString += Server.UrlEncode(row["path"].ToString().Trim()) + "■";                        returnString += row["path"].ToString().Trim() + "■";                    }                    Response.Clear();                    Response.ContentEncoding = Encoding.GetEncoding("GB2312");                    Response.Write(returnString.TrimEnd('■'));//此处回传数据                    Response.End();                }            }        }    }}

function AddRows(tab,rowCount,columCount,sourec){    var items;    if(sourec != "")    {        items = sourec.split('■');    }    for(var i = 0;i < rowCount;i++)    {        var newRow = tab.insertRow();        if(i%2 == 0)            newRow.style.background = "Pink";        else            newRow.style.background = "Green";                    for(var j = 0;j < columCount;j++)        {            var newCell = newRow.insertCell();            var bName = "";            var path = "";            if(i*5+j < items.length)            {                bName = items[i*5+j].split('□')[0];                path = items[i*5+j].split('□')[1];            }            newCell.innerHTML = "<a id = 'a_"+i+"_"+j+"' href = 'Content.aspx?path="+encodeURI(path)+"'>"+bName+"</a>";//此处path出现乱码！！！！！！        }    }}