session

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January 16, 2009 at 11:01 PM

Hi friend,

There are a number of problems that arise from the fact that HTTP is a "stateless" protocol. In particular, when you are doing on-line shopping, it is a real annoyance that the Web server can't easily remember previous transactions.In session tracking maintain the state of a user throughout
when the user complete the shopping.

There are four types of Session Tracking
1.Session
2.Cookies
3.Url-rewriting
4.Hidden

Code for Session solve the problem and some step to be remember:

1.Code to login the user.

"login.jsp"

<html>
<head>
<script>
function validLogin()
{
if(document.loginform.userName.value=="")
{
alert("Please enter username.");
document.loginform.userName.focus();
return false;
}
if(document.loginform.password.value=="")
{
alert("Please enter password.");
document.loginform.password.focus();
return false;
}
return true;
}
</script>
</head>
<body>
<form name="loginform" method="post" action="loginaction.jsp" onsubmit="return validLogin();">
<table>
<tr>
<td colspan=2>
<h1>User Login</h2>
</td>
</tr>

<tr>
<td>Login Name</td>
<td><input type="text" name="userName" value=""></td>
</tr>
<tr>
<td>Password</td>
<td><input type="password" name="password" value=""></td>
</tr>

<tr>
<td></td>
<td><input type="submit" name="Submit" value="Submit"></td>
</tr>
</table>
</form>

</body>
</html>

January 16, 2009 at 11:09 PM

step 2 : When the user successfully login set the user in session

<%@ page language="java" import="java.sql.*;"%>
<%

String userName = request.getParameter("userName");
String password = request.getParameter("password");

System.out.println("MySQL Connect Example.");
Connection conn = null;
String url = "jdbc:mysql://localhost:3306/";;;
String dbName = "userlogin";
String driver = "com.mysql.jdbc.Driver";
String username = "root";
String userPassword = "root";
try {
Class.forName(driver).newInstance();
conn = DriverManager.getConnection(url+dbName,username,userPassword);
Statement st = conn.createStatement();
String strQuery = "select count(*) from user where username='"+userName+"' and password='"+password+"'";
out.println(strQuery);
ResultSet rs = st.executeQuery(strQuery);

if(rs.next())
{
if(rs.getInt(1)>0)
{
session.setAttribute("userid",userName);
response.sendRedirect("welcome.jsp");
}
else
{
response.sendRedirect("login.jsp");
}
}
System.out.println("Connected to the database");
conn.close();
System.out.println("Disconnected from database");
} catch (Exception e) {
e.printStackTrace();
}
%>

January 16, 2009 at 11:11 PM

3.If the user succesfully the it goes to "welcome.jsp" else back to the "loginaction.jsp"

"welcome.jsp"

<html>
<body>
<%
String user = session.getAttribute("userid").toString();
%>
<br><br>
<h1>Welcome
<%= user%></h1>
</body>
</html>

Thanks