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Session tracking in servlets by using HttpSession
over 8 years ago
HttpSession Interface
It is one of the session tracking techniques.
It basically creates a session for each user and is used to maintain the request data and time interval of a particular. A user may give more than one requests at a particular time, so all the requests should be maintained under a session.i.e previous request should not be destroyed when new request is generated.It creates a session Id for each user which serves as the identity of that particular user.
A session object is created each id and it is destroyed after the session so that another user is not able to access that data.
Getting HttpSession object:
public HttpSession getSession(): It is used to get the current session for a particular request or it creates a new session if session doesn't exist.
Some commonly used methods for this are:
- public String getId(): It returns the unique id associated with a session.
- public void invalidate(): It is used to finish the session by destroying the session object.
Example:
index.html
<form action="demo1"> User Name<input type="text" name="uname"/><br/> <input type="submit" value="submit"/> </form>
Demo1.java (Servlet 1)
import java.io.*; import javax.servlet.*; import javax.servlet.http.*; public class Demo1 extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response){ try{ response.setContentType("text/html"); PrintWriter out = response.getWriter(); String name=request.getParameter("uname"); HttpSession session=request.getSession(); session.setAttribute("username",name); out.print("<html><body><a href='demo2'>go</a></body></html>"); out.close(); }catch(Exception e){System.out.println(e);} } }Demo2.java( Second servlet)
import java.io.*; import javax.servlet.*; import javax.servlet.http.*; public class Demo2 extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) try{ response.setContentType("text/html"); PrintWriter out = response.getWriter(); HttpSession session=request.getSession(); String name=(String)session.getAttribute("username"); out.print("Welcome "+name); out.close(); }catch(Exception e){System.out.println(e);} } }
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