Here I'm Posting very Interesting and useful to validate a user using Servlet, ajax and jquery using database.
Download file a js file: jquery-1.3.2.js from here: http://jquery.com/download/
First Step:
1. Create a table user
create table user(username varchar(30), password varchar(10));
2. Create a login 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>
<title>Login Page</title>
<script type="text/javascript" src="js/jquery-1.3.2.js"></script>
<script type="text/javascript">
var x="<%=session.getMaxInactiveInterval()%>";
function sendAjax()
{
var userName= $('#userName').val();
var url='login';
$.post("login",{userName:userName},showAlert);
}
function showAlert(data)
{
//if(data!=null && data!='NotFound'){
if(data=="found"){
$('#message').html('Congratulations! Correct user name')
$('#message').css({"color":"white", "background-color":"green"});
}
else{
$('#message').html('User Details Not Found!')
$('#message').css({"color":"white", "background-color":"red","font-weight":"bold"});
}
}
</script>
</head>
<body>
<form action="login" method="post">
<h1>Login Page!</h1>
<table>
<tr>
<td>Please enter your userName:</td>
<td>
<td><input type="text" name="userName" id="userName" onchange="sendAjax();"></td><td><span id="message" ></span></td>
</tr>
<tr>
<td>Please enter Your password:</td>
<td>
<td><input type="password" name="pass"></td>
</tr>
<tr>
<td> </td>
<td><input type="button" value="submit" onclick="sendAjax()"></td>
</tr>
</table>
<div id="mm"></div>
</form>
</body>
</html>
1. Create a bean class for user information.
package com.vikash.model;
public class Bean {
String firstName;
String lastName;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
}
2. create a class DAOImpl
package com.vikash.service;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import com.vikash.model.Bean;
public class DAOImpl {
static Connection con = null;
static ResultSet resultSet = null;
static ResultSet resultSet2 = null;
static Statement stat = null;
public String firstName;
public String lastName;
Bean bean=new Bean();
Map<String,Bean>myModel=new HashMap<String,Bean>();
static PreparedStatement preparedStatement;
static PreparedStatement preparedStatement2;
public static void main(String args[]) throws SQLException {
Map<String, Bean>map=new HashMap<String,Bean>();
DAOImpl dImpl=new DAOImpl();
Bean bean=new Bean();
map=dImpl.getDetails("vikash", "kumar");
Set<Map.Entry<String, Bean>> set=map.entrySet();
Iterator<Map.Entry<String, Bean>>itr=set.iterator();
//Map.Entry<String, Bean>me=map.entrySet();
while(itr.hasNext()){
bean=itr.next().getValue();
}
System.out.println("First Name:"+bean.getFirstName());
System.out.println("Last Name:"+bean.getLasName());
}
public Map<String,Bean> getDetails(String userName, String pass) throws SQLException {
String query = "select * from user where username='" + userName
+ "' AND pass='" + pass + "'";
String query2="select * from user where username=?";
String query3="update table user set lastname=singh where lastname=?";
System.out.println(query);
try {
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection("jdbc:mysql://localhost/joining",
"root", "vikash");
preparedStatement = con.prepareStatement(query2);
preparedStatement.setString(1, userName);
resultSet = preparedStatement.executeQuery();
if (resultSet.next()) {
bean.setFirstName(resultSet.getString(1));
bean.setLasName(resultSet.getString(2));
myModel.put("model", bean);
}
} catch (Exception e) {
e.printStackTrace();
// TODO: handle exception
}
return myModel;
}
}
4. Create a class Login Serlvet
package com.vikash.web;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.vikash.service.DAOImpl;
public class LoginServlet extends HttpServlet {
/**
*
*/
public LoginServlet(){
System.out.println("Login Servlet Invoked");
}
private static final long serialVersionUID = 1L;
public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
PrintWriter out=response.getWriter();
DAOImpl dImpl = new DAOImpl();
String userName = request.getParameter("userName");
String pass = request.getParameter("pass");
Map<String, Bean>myMap=new HashMap<String, Bean>();
try {
if (dImpl.getDetails(userName, pass).size()>0) {
HttpSession httpSession = request.getSession(true);
myMap=dImpl.getDetails(userName, pass);
out.print("found");
}
else{
out.print("NotFound");
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(userName);
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
// This is for testing purpose
public static void main(String args[]) throws SQLException{
DAOImpl dImpl = new DAOImpl();
Map<String, Bean>myMap=new HashMap<String, Bean>();
myMap=dImpl.getDetails("vikash", "kumar");
System.out.println("gggggg:"+myMap.get("model").getFirstName());
}
}
output:
