<script src="Scripts/jquery-1.2.6.min.js" type="text/javascript"></script>
      <script type="text/javascript">
function getCookie(name)//取cookies函数        
          {
var arr = document.cookie.match(new RegExp("(^| )" + name + "=([^;]*)(;|$)"));
if (arr != null) return unescape(arr[2]); return null;
          }
          $(function () {
              $("#btn").click(function () {
                  $("#read").val(getCookie('username'));
              })
          }) 


</script> 

<form id="form1" runat="server">
<div>
<input type="text" id="txt" name="txts" /><asp:Button ID="Button1" runat="server"  Text="写cookie" onclick="Button1_Click" /><br />
<input type="text" id="read" /><input type="button" id="btn" value="读cookie" />
</div>
</form>

public static string test;
protected void Page_Load(object sender, EventArgs e)
        {

        }
protected void Button1_Click(object sender, EventArgs e)
        {
            test = HttpContext.Current.Request.Form["txts"];         
            test = HttpUtility.UrlEncodeUnicode(test);//对字符串进行js式escape编码。
            HttpCookie txtcookie = new HttpCookie("username", test);
            DateTime dt = new DateTime();
            dt = DateTime.Now;
            TimeSpan ts = new TimeSpan(0, 0, 1, 0);
            txtcookie.Expires = dt.Add(ts);
            Response.SetCookie(txtcookie);
        }