You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
44 lines
1.3 KiB
Java
44 lines
1.3 KiB
Java
Handling invalid sessions
|
|
|
|
package com.ack.web.servlet;
|
|
|
|
import java.io.IOException;
|
|
import java.io.PrintWriter;
|
|
import javax.servlet.ServletException;
|
|
import javax.servlet.http.HttpServlet;
|
|
import javax.servlet.http.HttpServletRequest;
|
|
import javax.servlet.http.HttpServletResponse;
|
|
import javax.servlet.http.HttpSession;
|
|
|
|
public class HandlingInvalidSessions extends HttpServlet {
|
|
public void goGet( HttpServletRequest req, HttpServletResponse res )
|
|
throws ServletException, IOException {
|
|
res.setContentType( "text/html" );
|
|
PrintWriter pw = res.getWriter();
|
|
pw.println( "<HTML><BODY>" );
|
|
|
|
HttpSession theSession = req.getSession();
|
|
|
|
try {
|
|
Object obj = theSession.getAttribute( "counter" );
|
|
|
|
/**
|
|
* the above call will throw an IllegalStateException
|
|
* if theSession has been invalidated (e.g. by the
|
|
* container or by another servlet)
|
|
*
|
|
* a defensive servlet programmer should wrap all accesses
|
|
* to a servlet session (not just getAttribute()) in a
|
|
* try/catch block so that they can take the appropriate
|
|
* action to handle the case where a session is destroyed
|
|
* at anytime
|
|
*/
|
|
}
|
|
catch( IllegalStateException ise ) {
|
|
// handle invalid session here
|
|
}
|
|
|
|
pw.println( "</BODY></HTML>" );
|
|
}
|
|
}
|