I need make sessions in Java web application.
I found that sesstion makes in servlet calass by method getSession().
But i have a question about session parameters. For example i send to server login/pass and save it into session atributes. Okey. Next time i do something on client and send new params to server. Where i gonna send it? In another or same and i gonna use if else for handle params like this?
Another question: How to use params which i put in session(login/pass) in another classes?
UPDATE
I read about sessions. And have new question. How to use session params in enother class. I mean after login i send new params on server, read it in servlet and want to take a login/pass from session and send it with new params into another class.
As part of your request handling in a doGet or doPost method, here is how you can get session and use it to get and set variables.
//Obtain the session object, create a new session if doesn't exist
HttpSession session = request.getSession(true);
//set a string session attribute
session.setAttribute("MySessionVariable", "MySessionAtrValue");
//get a string sessson attribute
String strParam = session.getAttribute("MySessionVariable");
//get an integer sessioin attribute
Integer param = (Integer) session.getAttribute("MySessionVariable");
//set an integer session attribute
session.setAttribute("MySessionVariable", new Integer(param.intValue() + 1));
Session is associated with each request . Now it depends whether client join the session or not there are three overloaded methods of getSession() to get more about them please go through the documents. Now if session is aleady associated with the request get existing session set the attribute in session and vice-versa if not create new session and do the same.
if the server used only cookie-based sessions, and the client had disabled the use of cookies, then a session would be new on each request.
I hope this helped.
Related
On server side I'm using Java and on the client side Ionic1.
I'm setting Java object to session like this:
session.setAttribute("userId", userObj.getUserId());
After setting session i need to get that session in another method, that time I'm using like this
Long userId = (Long) session.getAttribute("userId");
Here if i send request from mobile to server I will get session.getAttribute value.
But I sent request from browser to server that time I will get session.getAttribute value is NULL
Make sure you are calling the getAttribute() only after the session has been created. Its a common mistake to access the session attributes when no session exists.
Basically, validate and make sure session exists and that the attribute value has been set in the application flow before trying to get the session attributes.
HttpSession session = request.getSession(true);
// true will create a session is does not already exists
if(session != null) {
// get your session attributes here.
// Your Session Attributes should be set before you're trying to access them
}
I want to differentiate between:
New session created by time-out of previous session.
A new session created by opening the page in new session of a browser.
Is there a way I can identify these two in a new HTTPServeletRequest?
You can implement SessionListener and manage to get new session and old session mapping,
However to decide where to redirect upon new login (as you commented)
you should store referrer header in session
For example:
after session has been destroyed
user gets redirected to login page
get the referrer header put it in session and on successful login read it from session and redirect there
my code,
HttpSession session = request.getSession(false);
// Details.l.info(" 1>>>>session ID is : " + session.getId());
Details.l.info("["+this.getClass()+"]"+"request from "+request.getRemoteHost());
if(session==null){
session = request.getSession(true);
Details.l.info("["+this.getClass()+"]"+"Session Created!!!!!!!!!!!!!!!!!!!#####$####");
Details.l.info(" 2>>>>>session ID is : " + session.getId());
}
Details.l.info(" 3>>>>>session ID is : " + session.getId());
// System.out.println("session ID is : " + session.getId());
Details DTO = new Details(request);
String loc = DTO.findMyLocation();
session.invalidate();
here, i am creating a session at the very beginning of the servlet with a logic that if the session already exists, then give hat session ID for that particular user or if a session does not exist for this particular user, please create a new session and then give the new session ID, here the new session is created inside the IF condition and i have tested in all possible ways (i have used two different systems and tried hitting to the servlet on one system too) but the control never gets into this loop where the session is getting created. but i see every time i hit to the servlet i get a new session ID!!! can someone please exlain this behavior of my servlet?? i am very new to sessions and servlets!!
Thanks in Advance..
JSPs implicitely create a session, unless session is set to false in the page directive:
<%# page session="false" %>
That's why your servlet always sees an already existing session. Simply enter the address of the servlet in the browser address bar (provided the code you posted is in the doGet() method), instead of going through the JSP to invoke it, and you should see the servlet create a new session.
EDIT: note that the spec says about this session attribute that it can be used to specify that the JSP doesn't participate in the session. Nothing guarantees that no session will be created when invoking the JSP. Only that, if you try to access the session from this JSP, you'll get an exception.
You may want to use request.getSession(true) to always create a session.
Hi in jsp of JavaScript i am checking userdId in session or not it always have session id if session expires also, but i checked in java Action class after session expires userid is null but not in jsp. code link
Try alerting the sessionId in your javascript code. You will find that the sessionId is different after the old one has expired.
Also check what the code is doing when a new session is created. It might be setting the userid in the new session.
How can we manage session Object if the cookies is disabled ?. how url encoding is used for this?
The servlet container will handle this for you. If you look at the url in the first time you hit your site, it will have used URL re-writing to append a JSESSIONID to the URL.
This is because the first time the server responds to the client it doesn't know if the client supports cookies or not. It has also written a cookie with the session id in, so on the second request it checks for the cookie and if present stops using URL re-writing, if not it carries on.
You have to use encodeRedirectURL in response object, Please refer this blog it will helpful for you.
http://mytechbites.blogspot.com/2009/08/servlet-session-management-when-cookies.html
it adds jSessionId at the end of URL to map request with session you probably need to configure your server for that too
Use HttpServletResponse.encodeURL() to append jsessionid to your URL, but it is considered harmful.
Find more details here
HTTP Sessions are the recommended approach. A session identifies the requests that originate from the same browser during the period of conversation. All the servlets can share the same session. The JSESSIONID is generated by the server and can be passed to client through cookies, URL re-writing (if cookies are turned off) or built-in SSL mechanism. Care should be taken to minimize size of objects stored in session and objects stored in session should be serializable. In a Java servlet the session can be obtained as follows:
HttpSession session = request.getSession(); //returns current session or a new session
Sessions can be timed out (configured in web.xml) or manually invalidated.