避免使用下一个url，直到类别名称是唯一的

这是Jsp代码。当我按下提交按钮时，我将使用javascript和ajax验证我的类别名称。它将在显示中询问类别名称。但与我使用ajax调用验证类别名称的唯一性相同，它将在蓝色时检查唯一性。当我第一次按下提交按钮，第二次按下时，它将转到主url

<form name="frm" action="createnewcatgoryBean.jsp" method="post">
    <table style="padding: 5px 0px 0px 8px;">
    <tr>
    <th colspan="2">
    <div style="width: width:271px; color:red;" id="validate"></div>
    </th>
    </tr>
    <tr>
    <th>Category Name<span>:</span></th><td><input id="cat"  onblur="return validatenewcat()" type="text" name="category">
    </td>
    </tr>
    <tr>
    <th>Quotations form<span>:</span></th><td><input type="checkbox" name="quotations"></td>
    </tr>
    <tr>
    <th>Agreement form<span>:</span></th><td><input type="checkbox" name="agreement"></td>
    </tr>
    <tr>
    <th>Payment form<span>:</span></th><td><input type="checkbox" name="payment"></td>
    </tr>
    <tr>
    <th>ETI<span>:</span></th><td><input type="checkbox" name="eti"></td>
    </tr>
    <tr>
    <td colspan="2" style="float:right; padding-top:15px">
    <input type="submit" value="Submit" onclick="return validatenewcat()" style="width: 60px;">
    </td>
    </tr>
    </table>
    </form>

这是我的ajax调用脚本和javascript

  function validatenewcat()
    {
        var category = document.getElementById("cat").value;
        if(category=="")
        {
            setTimeout(document.getElementById("validate").innerHTML="!PLz Enter The Category Name", 2000);
            return false;
        }   
        else
        {
        var url="catnamecheck.do?id="+category;
         xmlhttp.open("post", url,true);
         xmlhttp.send(null);
         xmlhttp.onreadystatechange=function()
         {
          if(xmlhttp.readyState==4)
          {       
                 if(xmlhttp.status==200)
                  { 
                     var temp = xmlhttp.responseText;
                  if(temp!="")
                     {
                         document.getElementById("validate").innerHTML="!PLz Enter The Unique Category Name";
                         document.getElementById("cat").focus();
                        return false; 
                     }
                  }
          }
        }
    }

    }

这是我的java代码

public Map<String, String> catuniqecheck(String id) {
    Connection c = null;
    PreparedStatement ps1 = null;
    ResultSet rs1 = null;
    String sql=null;
    try{
        c = JDBCHelper.getConnection();
        if(c!=null)
        {
            Map<String, String> map = new HashMap<String, String>();
            sql="select * from catgory where catgoryname=?";
            ps1=c.prepareStatement(sql);
            ps1.setString(1, id);
            ps1.execute();
            rs1=ps1.getResultSet();
            if(rs1.next())
            {
                System.out.println("insdide of the catuniqecheck");
                map.put("catgoryname",rs1.getString("catgoryname"));
                JSONObject json = new JSONObject();
                json.accumulateAll(map);
            }
            return map;
        }   
       else
         {  
               System.out.println("DB connection Established");
               return null  ;
         }
        }
        catch (Exception e) {
            // TODO: handle exception
               return null  ;
        }
finally{
            JDBCHelper.close(rs1);
            JDBCHelper.close(ps1);
            JDBCHelper.close(c);
       }
}

这是我的servlet代码

System.out.println("inside success");
                JSONObject json = new JSONObject();
                json.accumulateAll(result);
                response.setContentType("application/json");
                response.getWriter().write(json.toString());

当我第二次按提交时，它将转到另一个url plz帮助我感谢u