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Ajax:-


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Ajax means Asynchronous JavaScript and XML, it is used to partially update the content of the web page excluding complete web form.

Ajax improves the performance of web application and provide dynamic programming approach without reloading and submit the data.


for example, if we create a registration form and we want to check that email already exists when the user switches to the next text field then we can create ajax code to check email id.


when we select the country then the state list and when we select the state then the city list will be populated by AJAX.


when we search on Facebook or Google then the search box will populate when we press any key that will be managed by Ajax.




Role of JavaScript or Jquery:-

It is used to handle the event in Ajax Process, which means if we select a dropdown list and display data into another dropdown list, that will be managed by AJAX.


Role of XML:-

XML means Extensible markup language which is used to transfer data from client machine(Browser) to server machine (Apache Server) and server machine to the server machine.

XMLHttpRequest:-  this class is used to send data from browser to web server.

XMLHttpResponse:-  It is used to get web server response using XML form.



Create Search Box which will search the respective record from the database and show it into the browser?




Code of Index.JSP:-


<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
        <script>
            function showdata(a)
            {
                xmlhttp = new XMLHttpRequest();
                xmlhttp.onreadystatechange=function()
                {
                document.getElementById("res").innerHTML= xmlhttp.responseText;       
                }
                xmlhttp.open("POST","showdata.jsp?q="+a,true);
                xmlhttp.send();
             
            }
         
        </script>
    </head>
    <body>
        <input type="text" placeholder="enter any data" id="txtsearch" onkeyup="showdata(this.value)" />
        <br>
        <br>
        <div id="res">
         
        </div>
    </body>
</html>



Code for ShowData.jsp

<%@page import="java.sql.*" %>
<%
                   
    String data = request.getParameter("q")+ "%";
    Class.forName("com.mysql.jdbc.Driver");
    Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/javadb","root","");
    Statement st = con.createStatement();
    ResultSet res = st.executeQuery("select * from reg where fullname like '"+data+"'");
    while(res.next())
    {
        out.print(res.getString(1)+" "+res.getString(2)+" "+res.getString(3)+" "+res.getString(4)+ " " + res.getString(5) +"<hr>");
    }
    
  %>
   

Another Example USer Already Exist:-


<%-- 
    Document   : RegisterForm
    Created on : Oct 14, 2019, 10:16:53 AM
    Author     : DELL
--%>

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
        <script>
            function chkemail(a)
            {
                xmlhttp = new XMLHttpRequest();
                xmlhttp.onreadystatechange=function()
                {
                document.getElementById("res").innerHTML= xmlhttp.responseText;         
                }
                xmlhttp.open("POST","chkdata.jsp?q="+a,true);
                xmlhttp.send();
            }
        </script>
    </head>
    <body>
        <form action="RegSer" method="post">
            
            <p>Enter emailid</p>
            <p><input type="email" name="txtemail" required="" onblur="chkemail(this.value)"  /> </p>
           <div id="res">
           </div>
            <p>Enter password</p>
            <p><input type="password" name="txtpass" required=""  /> </p>
            <p>Enter mobileno</p>
            <p><input type="number" name="txtmobile"  required="" /> </p>
            <p>Enter fullname</p>
            <p><input type="text" name="txtfname" required="" /> </p>
            <p><input type="submit" name="btnsubmit" value="Click" /></p>
            
            
            
            
        </form>
    </body>
</html>


Ajax code:-

chkdata.jsp

<%@page import="java.sql.*" %>
<%
                   
    String data = request.getParameter("q");
    Class.forName("com.mysql.jdbc.Driver");
    Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/javadb","root","");
    Statement st = con.createStatement();
    ResultSet res = st.executeQuery("select * from reg where email = '"+data+"'");
    if(res.next())
    {
    out.print("emailid already exist"); 
    }
    
  %>
   


Check Email ID Already Exist using focus()


Create Design File of Registration page

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
<script>
function checkemail(a)
{
var xmlhttp = new XMLHttpRequest();
   xmlhttp.onreadystatechange=function()
   {
   if(xmlhttp.readyState==4 && xmlhttp.status==200)
   {
  
  
   if(xmlhttp.responseText.length>=33)
   {
   document.getElementById("res").innerHTML = xmlhttp.responseText;  
   document.getElementById("txtemail").focus();
      
    }
   else
   {
   
   document.getElementById("txtmobile").focus();
   }
   }
   }
   xmlhttp.open("POST","checkemail.jsp?q="+a,true);
   xmlhttp.send();
 
}

</script>
</head>
<body>
<h1>USER Login HERE</h1>
<form action="../Regser" method="post">
<input type="text" name="txtuser" placeholder="enter name" required/> <br><br>
<input type="password" name="txtpass" placeholder="enter password" required/><br><br>
<input type="email" name="txtemail" id="txtemail" placeholder="enter email" onblur="checkemail(this.value)" required/> <div id="res"></div></div><br><br>
<input type="mobile" name="txtmobile" id="txtmobile" placeholder="enter mobile"  required/><br><br>
<input type="Submit" value="submit"/>

</form>

</body>
</html>


Create Ajax File

Before this file create Dataaccessfile class JDBCExample2.java and Write the following code

class JDBCExample2
{
    public static boolean checkEmail(String email) throws SQLException
   {
   ResultSet res=st.executeQuery("select * from tbl_reg  where email='"+email+"'");
       return res.next();
       
   
   }

}

        
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<%@page import="java.sql.*" %>   
<%@page import="dal.*" %> 
<%
JDBCExample2.connect();
boolean res=JDBCExample2.checkEmail(request.getParameter("q"));
String s="";
if(res)
s="Email already exist";
}
else
{
s="";
}
out.print(s);
%>

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