How to prevent the page refresh while submitting the form??

Hi. Requirement: There are two drop down boxes.Dropdown2 should load corresponding to the select of Dropdown1. Im hitting a db for this every time.Hence the page loads every time when changing Dropdown1. Is there any way in JAVA SCRIPT to prevent this page loading???

Thanks much!!

View Answers

June 20, 2011 at 11:00 AM

1)country.jsp:

 <%@page import="java.sql.*"%>
 <html>
      <head>  
      <script language="javascript" type="text/javascript">  
      var xmlHttp  
      var xmlHttp
      function showState(str){
      if (typeof XMLHttpRequest != "undefined"){
      xmlHttp= new XMLHttpRequest();
      }
      else if (window.ActiveXObject){
      xmlHttp= new ActiveXObject("Microsoft.XMLHTTP");
      }
      if (xmlHttp==null){
      alert("Browser does not support XMLHTTP Request")
      return;
      } 
      var url="state.jsp";
      url +="?count=" +str;
      xmlHttp.onreadystatechange = stateChange;
      xmlHttp.open("GET", url, true);
      xmlHttp.send(null);
      }

      function stateChange(){   
      if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete"){   
      document.getElementById("state").innerHTML=xmlHttp.responseText   
      }   
      }

        </script>  
      </head>  
      <body>  
      <select name='country' onchange="showState(this.value)">  
       <option value="none">Select</option>  
    <%
 Class.forName("com.mysql.jdbc.Driver").newInstance();  
 Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","root");  
 Statement stmt = con.createStatement();  
 ResultSet rs = stmt.executeQuery("Select * from country");
 while(rs.next()){
     %>
      <option value="<%=rs.getString(1)%>"><%=rs.getString(2)%></option>  
      <%
 }
     %>
      </select>  
      <br>  
      <div id='state'>  
      <select name='state' >  
      <option value='-1'></option>  
      </select>  
      </div>  
      </body> 
      </html>

2)state.jsp:

<%@page import="java.sql.*"%>
<%
String country=request.getParameter("count");  
 String buffer="<select name='state' ><option value='-1'>Select</option>";  
 try{
 Class.forName("com.mysql.jdbc.Driver").newInstance();  
 Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","root");  
 Statement stmt = con.createStatement();  
 ResultSet rs = stmt.executeQuery("Select * from state where countryid='"+country+"' ");  
   while(rs.next()){
   buffer=buffer+"<option value='"+rs.getString(1)+"'>"+rs.getString(3)+"</option>";  
   }  
 buffer=buffer+"</select>";  
 response.getWriter().println(buffer); 
 }
 catch(Exception e){
     System.out.println(e);
 }
 %>