I want to create a JSR 286 Portlet named VisitCounter to install on websphere Portal 8.0. VisitCounter counts the number of user online.
public void doView(RenderRequest request, RenderResponse response) throws PortletException, IOException {
// Set the MIME type for the render response
response.setContentType(request.getResponseContentType());
// Check if portlet session exists
VisitCounterPortletSessionBean sessionBean = getSessionBean(request);
if( sessionBean==null ) {
//response.getWriter().println("<b>NO PORTLET SESSION YET</b>");
return;
}
........
}
How to make this?
Thanks!
public void doView(RenderRequest request, RenderResponse response) throws PortletException, IOException {
// Set the MIME type for the render response
response.setContentType(request.getResponseContentType());
// Check if portlet session exists
VisitCounterPortletSessionBean sessionBean = getSessionBean(request);
if( sessionBean==null ) {
//response.getWriter().println("<b>NO PORTLET SESSION YET</b>");
return;
}
........
}
Using application scope...
Related
In Spring Security, how to exclude one particular URL from resetting the session timeout? Overall application session timeout(server.servlet.session.timeout) is 15 minutes. We have a ajax call from the web page that will get called every 1 minute. This call needs to be secured, but should not impact the session time.
We have tried adding a filter extending ConcurrentSessionFilter. Also, a filter extending SessionManagementFilter. Adding ignoring() skips authentication too. Nothing helped. Can this requirement be achieved in Spring Security? Any suggestions?
This is how i handled it. Just sharing, it may be of help to someone. Please share any better ways.
Spring Security filter is added as last in the chain.
http.addFilterAfter(new SessionInvalidationFilter(timeOutInMinutes), SwitchUserFilter.class);
It keeps track of a lastUpdatedTime, which gets updated for all calls except for those URLs that needs to be ignored. In case, the differential time is greater than the configured timeout, session gets invalidated.
public class SessionInvalidationFilter extends GenericFilterBean {
private static final String LASTUPDATEDDATETIME = "LASTUPDATEDDATETIME";
private static final List<String> ignoredURLs = Arrays.asList("/Notifications/number"); // this is the AJAX URL
private int timeOutInMinutes = 15;
public SessionInvalidationFilter(int timeOutInMinutes) {
this.timeOutInMinutes = timeOutInMinutes;
}
#Override
/**
* LASTUPDATEDDATETIME is updated for all calls except the ignoredURLs.
* Session invalidation happens only during the ignoredURLs calls.
*/
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
HttpSession session = request.getSession(false);
try {
if (session != null && request.getRequestURI() != null) {
if (ignoredURLs.contains(request.getRequestURI())) {
Object lastUpdatedDateTimeObject = session.getAttribute(LASTUPDATEDDATETIME);
if (lastUpdatedDateTimeObject != null) {
LocalDateTime lastUpdatedDateTime = (LocalDateTime) lastUpdatedDateTimeObject;
long timeInMinutes = ChronoUnit.MINUTES.between(lastUpdatedDateTime, LocalDateTime.now());
if (timeInMinutes >= timeOutInMinutes) {
log.info("Timing out sessionID:{}", session.getId());
session.invalidate();
SecurityContextHolder.clearContext();
}
}
} else {
session.setAttribute(LASTUPDATEDDATETIME, LocalDateTime.now());
}
}
} catch (Exception e) {
log.error("Exception in SessionInvalidationFilter", e);
}
chain.doFilter(request, response);
}
}
I would like to block the access of some page even if the user knows the url of some pages.
For example, /localhost:8080/user/home.xhtml (need to do the login first) if not logged then redirect to /index.xhtml.
How do that in JSF ? I read in the Google that's needed a filter, but I don't know how to do that.
You need to implement the javax.servlet.Filter class, do the desired job in doFilter() method and map it on an URL pattern covering the restricted pages, /user/* maybe? Inside the doFilter() you should check the presence of the logged-in user in the session somehow. Further you also need to take JSF ajax and resource requests into account. JSF ajax requests require a special XML response to let JavaScript perform a redirect. JSF resource requests need to be skipped otherwise your login page won't have any CSS/JS/images anymore.
Assuming that you've a /login.xhtml page which stores the logged-in user in a JSF managed bean via externalContext.getSessionMap().put("user", user), then you could get it via session.getAttribute("user") the usual way like below:
#WebFilter("/user/*")
public class AuthorizationFilter implements Filter {
private static final String AJAX_REDIRECT_XML = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>"
+ "<partial-response><redirect url=\"%s\"></redirect></partial-response>";
#Override
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws ServletException, IOException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
HttpSession session = request.getSession(false);
String loginURL = request.getContextPath() + "/login.xhtml";
boolean loggedIn = (session != null) && (session.getAttribute("user") != null);
boolean loginRequest = request.getRequestURI().equals(loginURL);
boolean resourceRequest = request.getRequestURI().startsWith(request.getContextPath() + ResourceHandler.RESOURCE_IDENTIFIER + "/");
boolean ajaxRequest = "partial/ajax".equals(request.getHeader("Faces-Request"));
if (loggedIn || loginRequest || resourceRequest) {
if (!resourceRequest) { // Prevent browser from caching restricted resources. See also https://stackoverflow.com/q/4194207/157882
response.setHeader("Cache-Control", "no-cache, no-store, must-revalidate"); // HTTP 1.1.
response.setHeader("Pragma", "no-cache"); // HTTP 1.0.
response.setDateHeader("Expires", 0); // Proxies.
}
chain.doFilter(request, response); // So, just continue request.
}
else if (ajaxRequest) {
response.setContentType("text/xml");
response.setCharacterEncoding("UTF-8");
response.getWriter().printf(AJAX_REDIRECT_XML, loginURL); // So, return special XML response instructing JSF ajax to send a redirect.
}
else {
response.sendRedirect(loginURL); // So, just perform standard synchronous redirect.
}
}
// You need to override init() and destroy() as well, but they can be kept empty.
}
Additionally, the filter also disabled browser cache on secured page, so the browser back button won't show up them anymore.
In case you happen to use JSF utility library OmniFaces, above code could be reduced as below:
#WebFilter("/user/*")
public class AuthorizationFilter extends HttpFilter {
#Override
public void doFilter(HttpServletRequest request, HttpServletResponse response, HttpSession session, FilterChain chain) throws ServletException, IOException {
String loginURL = request.getContextPath() + "/login.xhtml";
boolean loggedIn = (session != null) && (session.getAttribute("user") != null);
boolean loginRequest = request.getRequestURI().equals(loginURL);
boolean resourceRequest = Servlets.isFacesResourceRequest(request);
if (loggedIn || loginRequest || resourceRequest) {
if (!resourceRequest) { // Prevent browser from caching restricted resources. See also https://stackoverflow.com/q/4194207/157882
Servlets.setNoCacheHeaders(response);
}
chain.doFilter(request, response); // So, just continue request.
}
else {
Servlets.facesRedirect(request, response, loginURL);
}
}
}
See also:
Our Servlet Filters wiki page
How to handle authentication/authorization with users in a database?
Using JSF 2.0 / Facelets, is there a way to attach a global listener to all AJAX calls?
Avoid back button on JSF web application
JSF: How control access and rights in JSF?
While it's of course legitimate to use a simple Servlet filter, there are alternatives like
Spring Security
Java EE Security
Apache Shiro
I am working on a JSF 2.0 website. The website has two kind of users(public and registered). Now I want to know that how can I create session for both kind of users? For registered users, when my user is login then there should be session for it, and when session expires then I redirect it to page that your session has expired. For public users there should be no session at all. Means there is no session time out for my public users and they never have messages that your session has expired. How can I implement this behavior in JSF 2.0.
Can I use filter for it or there is better approach for it? I also read that JSF automatically creates session using managed beans. Can I use these sessions for my task?
Edit:
I tell you what i did so you people better guide me in this scenerio
What i did i put a filter in my web app like this
<filter>
<filter-name>SessionTimeoutFilter</filter-name>
<filter-class>util.SessionTimeoutFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>SessionTimeoutFilter</filter-name>
<url-pattern>*.xhtml</url-pattern>
</filter-mapping>
Here is my Filter code
public class SessionTimeoutFilter implements Filter {
// This should be your default Home or Login page
// "login.seam" if you use Jboss Seam otherwise "login.jsf"
// "login.xhtml" or whatever
private String timeoutPage = "faces/SessionExpire.xhtml";
private String welcomePage = "faces/index.xhtml";
public static Boolean expirePage = false;
private FilterConfig fc;
#Override
public void init(FilterConfig filterConfig) throws ServletException {
this.fc = filterConfig;
}
#Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
throws IOException, ServletException {
HttpServletRequest httpServletRequest = (HttpServletRequest) request;
HttpServletResponse httpServletResponse = (HttpServletResponse) response;
HttpSession session = httpServletRequest.getSession();
/**
* The session objects have a built-in data structure (a hash table) in which you can store
* any number of keys and associated values. You use session.getAttribute("key") to look up
* a previously stored value. The return type is Object, so you must do a typecast to
* whatever more specific type of data was associated with that attribute name in the session.
* The return value is null if there is no such attribute, so you need to check for null
* before calling methods on objects associated with sessions.
*
* Note:
* JSF session scoped managed beans are under the covers stored as a HttpSession
* attribute with the managed bean name as key.
*/
Login login = (Login)session.getAttribute("login");
if (login == null) { // No such object already in session
filterChain.doFilter(request, response);
} else {
/**
* If you use a RequestDispatcher, the target servlet/JSP receives the same
* request/response objects as the original servlet/JSP. Therefore, you can pass
* data between them using request.setAttribute(). With a sendRedirect(), it is a
* new request from the client, and the only way to pass data is through the session or
* with web parameters (url?name=value).
*/
filterChain.doFilter(request, response);
}
System.out.println();
} //end of doFilter()
#Override
public void destroy() {
} //end of destroy()
Now what happen that if you first time enter url of my site then this filter invoke. It gets
Login login = (Login)session.getAttribute("login");
null. So it simply move to my index.xhtml page. Now my index.html page constructor invokes. Here is my code
#ManagedBean
//////#RequestScoped
#SessionScoped
public class Login implements Serializable {
//Constructor
public Login() {
FacesContext facesContext = FacesContext.getCurrentInstance();
ExternalContext externalContext = facesContext.getExternalContext();
//getSession(false), which returns null if no session already exists for the current client.
HttpSession session =(HttpSession)externalContext.getSession(false);
if (session == null) {
System.out.println();
} else {
session.setAttribute("logedin", 0); //public user
session.setMaxInactiveInterval(-1); // no session time out
Enumeration e = session.getAttributeNames();
while (e.hasMoreElements()) {
/**
* Here you also get "login" attr. Because when managed bean create the
* session, it sets you managedBean name in the session attribute.
*/
String attr = (String)e.nextElement();
System.err.println("attr = "+ attr);
Object value = session.getAttribute(attr);
System.err.println("value = "+ value);
} //end of while
}
}//end of constructor
} //end of class Login
when first time user come to my site then it is not login so i set logedin session attribute 0. Now suppose user enter credentials and press log in button. First my filter is invoke but this time it will get login attribute and comes to my doFilter() else check and then come to My validUser() method. Here is my code
public String validUser() throws Exception {
ArrayList2d<Object> mainarray = new ArrayList2d<Object>();
mainarray.addRow();
mainarray.add(userName);
mainarray.add(password);
busBeans.usermanagement.users um = new busBeans.usermanagement.users();
ArrayList retrieveList = um.getValidUser(mainarray); //database check of user existence
if (Integer.parseInt(retrieveList.get(0).toString()) == 0) {
ArrayList str = (ArrayList) retrieveList.get(1);
FacesContext facesContext = FacesContext.getCurrentInstance();
ExternalContext externalContext = facesContext.getExternalContext();
//getSession(false), which returns null if no session already exists for the current client.
HttpSession session =(HttpSession)externalContext.getSession(false);
if (session == null) {
System.out.println();
} else {
Enumeration e = session.getAttributeNames();
while (e.hasMoreElements()) {
String attr = (String)e.nextElement();
System.err.println("attr = "+ attr);
Object value = session.getAttribute(attr);
System.err.println("value = "+ value);
} //end of while
}
logedin=true;
session.setAttribute("logedin", 1);
session.setAttribute("firstLastName", str.get(7).toString());
session.setAttribute("getusercredentials", str);
session.setAttribute("sessionUserId", str.get(0).toString());
session.setAttribute("sessionRoleId",str.get(1).toString());
firstLastName = session.getAttribute("firstLastName").toString();
session.setMaxInactiveInterval(60); //1 min
ConnectionUtil.setRgihts(Integer.parseInt(str.get(0).toString()) , Integer.parseInt(str.get(1).toString()) ,Integer.parseInt(str.get(5).toString()));
checkRgihts();
}
} //end of validUser()
Now i want to ask one thing. I set sessionTimeout using setMaxInterval. Is it ok or it is better to do in web.xml? Now whne timeOut expires then filter doesn't invoke. But suppose that I also attach HttpSessionListener. Then on session time Out its destroy method invoke. I can invalidate session here. Like this.
public class MySessionListener implements HttpSessionListener {
// Constructor
public MySessionListener() {
} //end of constructor
#Override
public void sessionCreated(HttpSessionEvent event) {
System.out.println("Current Session created : " + event.getSession().getCreationTime());
System.out.println();
} //end of sessionCreated()
#Override
public void sessionDestroyed(HttpSessionEvent event) {
// get the destroying session...
HttpSession session = event.getSession();
if (session != null) {
session.invalidate();
}
System.out.println();
} //end of sessionDestroyed()
} //end of class MySessionListener
But on session expiration i also want to redirect user to redirecr Page if this is a registered user. IF this is a public user i don't want to redirect it although session has expired. I can check in the destroy method by getting attribute logedin that it is a public user or registered user. But then how can i redirect for registered user or do nothing for public user.
If somehow my filter invoke on session time out and some how i check that if this is a registered user by getting logedin attribute 1 and session time out has expired, because for public user i set timeout -1, then redirect the user, using RequestDispatcher otherwoise do filterChain.doFilter(request, response);.
So this is the scenerio that i implemented. I don't know whether my approaches are right or not ? I don't know what security issues i will face by this approach. So that's it.. Now you people guide me what should i do.....
Thanks
I understand what your goal is, but I don't think that not having a Session for unauthenticated users is particularly the best approach.
Consider an unauthenticated user navigating through a Primefaces wizard as he provides information to sign up for an account, (Eg. Pick Username, Provide Password, Choose Security Questions, etc...)
You are not going to want to persist this user information until it all has been collected and validated, because perhaps the user has a change of heart and decides not to sign up? Now you have an incomplete user record in your database that needs to be cleaned.
The answer is that you need to store this information in a ViewScoped bean or in session until the unauthenticated user confirms the account creation, where it can finally be persisted.
What I feel the best approach would be is for you to give a User a unique Role with one role being Unauthenticated. Using components like Spring Security 3 or even Seam you should be able to control page Authorization through the Role of the User in Session.
For instance, you can prevent unauthenticated users from entering pages in ../app/* or normal users from accessing pages in ../admin/*
I used some thing like this. First there is a filter. Here is my filter
#Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
throws IOException, ServletException {
HttpServletRequest httpServletRequest = (HttpServletRequest) request;
HttpServletResponse httpServletResponse = (HttpServletResponse) response;
//Send request to server after each 1min
// httpServletResponse.setIntHeader("Refresh", 60);
//getSession(false), which returns null if no session already exists for the current client
HttpSession session = httpServletRequest.getSession(false);
if (session == null) {
//session timeout check.
if (httpServletRequest.getRequestedSessionId() != null && !httpServletRequest.isRequestedSessionIdValid()) {
System.out.println("Session has expired");
/**
* getSession() (or, equivalently, getSession(true)) creates a new session if no
* session already exists.
*/
session = httpServletRequest.getSession(true);
session.setAttribute("logedin", "0"); // public user
//httpServletResponse.sendRedirect("http://www.google.com");
httpServletResponse.sendRedirect(timeoutPage);
} else {
session = httpServletRequest.getSession(true);
session.setAttribute("logedin", "0");
filterChain.doFilter(httpServletRequest, httpServletResponse);
}
} else {
String isRegisteredUser = session.getAttribute("logedin").toString();
if (isRegisteredUser.equalsIgnoreCase(("1"))) {
Login login = (Login)session.getAttribute("login");
Enumeration e = session.getAttributeNames();
System.out.println("");
filterChain.doFilter(httpServletRequest, httpServletResponse);
} else if (isRegisteredUser.equalsIgnoreCase(("0"))) {
Enumeration e = session.getAttributeNames();
filterChain.doFilter(httpServletRequest, httpServletResponse);
} //end of else if (isRegisteredUser.equalsIgnoreCase(("0")))
}
} //end of doFilter()
Now when user enter url of my site then this filter invoke. First time it get session null then it checks for session timeout. no session time out so it creates a session. Set logedin attribute to zero, means this is public user and pass the request. Here is my method
//constructor
public Login() {
try {
FacesContext facesContext = FacesContext.getCurrentInstance();
ExternalContext externalContext = facesContext.getExternalContext();
HttpServletRequest httpServletRequest = (HttpServletRequest)externalContext.getRequest();
//getSession(false), which returns null if no session already exists for the current client.
HttpSession session =(HttpSession)externalContext.getSession(false);
if (session == null) {
session = httpServletRequest.getSession(true);
session.setAttribute("logedin", "0");
session.setMaxInactiveInterval(-1);
System.out.println();
} else {
session.setAttribute("logedin", "0");
//No session timeout for public users
session.setMaxInactiveInterval(-1);
Enumeration e = session.getAttributeNames();
}
} catch (Exception e) {
System.out.println("Exception in session " + e.getMessage());
}
} //end of constructor
First time it gets session, just override the values so there is no harm to set the same attribute. But here i just want to ask one thing that is it ok to set no session time out for public users ? will it damage my application at some point, like my server goes out of memory and etc ? If yes, then how can i overcome this ?
Now suppose that my user is log in. Then my filter invoke, this time it will get a session so it comes to my isRegisterdUser check and check the value. He get 0 , just pass the request and then my valid user method call.
public String validUser() throws Exception {
String returnString = null;
ArrayList2d<Object> mainarray = new ArrayList2d<Object>();
mainarray.addRow();
mainarray.add(userName);
mainarray.add(password);
busBeans.usermanagement.users um = new busBeans.usermanagement.users();
ArrayList retrieveList = um.getValidUser(mainarray);
if (Integer.parseInt(retrieveList.get(0).toString()) == 0) {
ArrayList str = (ArrayList) retrieveList.get(1);
FacesContext facesContext = FacesContext.getCurrentInstance();
ExternalContext externalContext = facesContext.getExternalContext();
//getSession(false), which returns null if no session already exists for the current client.
HttpSession session =(HttpSession)externalContext.getSession(false);
if (session == null) {
System.out.println();
} else {
Enumeration e = session.getAttributeNames();
}
System.out.println();
logedin=true;
//Set session attributes for login users
session.setAttribute("logedin", 1);
session.setAttribute("firstLastName", str.get(7).toString());
session.setAttribute("getusercredentials", str);
session.setAttribute("sessionUserId", str.get(0).toString());
session.setAttribute("sessionRoleId",str.get(1).toString());
session.setAttribute("registeredUser", "true");
/**
* set session timeout for login user
* 1 min = 60 sec
* 5 min = 60 * 5 sec = 300 sec
*/
session.setMaxInactiveInterval(300); //5min
firstLastName = session.getAttribute("firstLastName").toString();
}
return returnString=null;
} //end of validUser()
I override the value of logedin attribute to 1 so now the user become valid user. Now if valid user make request then my filter invoke, it will get a session so it comes to my isRegisterdUser check, this time it get value 1 so just pass the request.Now when session time out and user make any request, then my filter invoke and this time it comes inside the check
if (httpServletRequest.getRequestedSessionId() != null && !httpServletRequest.isRequestedSessionIdValid()) {
System.out.println("Session has expired");
//httpServletResponse.sendRedirect("http://www.google.com");
httpServletResponse.sendRedirect(timeoutPage);
} else {
session = httpServletRequest.getSession(true);
session.setAttribute("logedin", "0");
filterChain.doFilter(httpServletRequest, httpServletResponse);
}
and redirect the user by making it public. So here how this i do it. I got also a idea that i refresh the page after some time, i have sessionCreationTime, sessionLastAccessTime and sessionMaxTime. so i can do a work like this
String isRegisteredUser = session.getAttribute("logedin").toString();
if (isRegisteredUser.equalsIgnoreCase(("1"))) {
Login login = (Login)session.getAttribute("login");
Enumeration e = session.getAttributeNames();
while (e.hasMoreElements()) {
String attr = (String)e.nextElement();
System.err.println("attr = "+ attr);
Object value = session.getAttribute(attr);
System.err.println("value = "+ value);
} //end of while
long sessionCreationTime = session.getCreationTime();
int sessionCreationTimeInSec = (int)(sessionCreationTime / 1000) % 60;
int sessionCreationTimeInMinutes = (int)((sessionCreationTime / (1000*60)) % 60);
long sessionLastAccessTime = session.getLastAccessedTime();
int sessionLastAccessTimeInSec = (int)(sessionLastAccessTime / 1000) % 60 ;
int sessionLastAccessTimeInMinutes = (int)((sessionLastAccessTime / (1000*60)) % 60 );
int sessionMaxTime = session.getMaxInactiveInterval();
int sessionMaxTimeInMinute = sessionMaxTime / 60 ;
if ((sessionCreationTimeInMinutes - sessionLastAccessTimeInMinutes) - 1 > sessionMaxTimeInMinute) {
System.out.println("Session is expiring in one minute");
}
System.out.println("");
filterChain.doFilter(httpServletRequest, httpServletResponse);
}
The idea here is that if some how you check that how much time left for session timeout then you can invalidate the session just before your session time out time. Because once your session expire you get session null and you have no attributes to check. But before one minute you have session and all session attributes so you can do whatever you want. I don't know how solid idea is this, it's just an approach that came to my mind.
Also suppose user is login and then suddenly closed the browser. Closing browser close the session. Now when you open your browser then you get a message that your session has expire. I want to ask when you open a browser can i use this check
if (httpServletRequest.getRequestedSessionId() != null && !httpServletRequest.isRequestedSessionIdValid()) {
System.out.println("Session has expired");
if (session.isNew()) {
/**
* getSession() (or, equivalently, getSession(true)) creates a new session if no
* session already exists.
*/
session = httpServletRequest.getSession(true);
session.setAttribute("logedin", "0"); // public user
filterChain.doFilter(httpServletRequest, httpServletResponse);
} else {
httpServletResponse.sendRedirect("http://www.google.com");
}
}
I used isNew() check because i want to do that if user is entering your site first time, like open his browser, then he didn't see the redirection message although his session has been expired because of closing browser.
Thanks
i am getting data from action class to servlet by adding data to session.whenever i am clicking the item in select list onchange event is fired that function is invoked the our servlet up to now OK,whenever we send second time request that servlet is not called why? and also comparsion is failed it will maintain previous values only.here i am sending request from ajax.pls can any one provide solution ?
AjaX code
function verify_details()
{
var resourceId=document.getElementById("res").value
var url="/EIS10/ResourceTest?resourceId="+resourceId;
ajax(url);
}
Action class Code:
listResource=taskService.getUserList(taskId);
System.out.println("The list Of Resources are::"+listResource);
HttpSession session=request.getSession();
session.setAttribute("listResource", listResource);
ServletCode
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
System.out.println("Servlet is Called...........");
String resourceId=request.getParameter("resourceId");
boolean t=false;
System.out.println("Your Clicked Id::"+resourceId);
HttpSession session=request.getSession();
List l=(List)session.getAttribute("listResource");
System.out.println("Resource List in Servlet:"+l);
if(l!=null)
{
System.out.println("The Size of List::"+l.size());
Iterator itr=l.iterator();
while(itr.hasNext())
{
String s=itr.next().toString();
System.out.println("Elements in List:"+s);
if(s.equals(resourceId))
t=true;
}
response.setContentType("text/html");
if (t) {
response.getWriter().write("Y");
} else {
response.getWriter().write("N");
}
}
}
}
It's probably because the browser returns the contents from its cache at the second request. See http://spacebug.com/solving_browser_caching_problem_of_ajax-html/ for a solution, or use an AJAX library (jQuery for example) which can handle this for you.
Besides, if you're using Struts, why do you use a bare servlet to handle your AJAX call? Why don't you use a Struts action?
I am using GWT for my client side application. However, I am not sure how I can handle session management. The GWT application resides on one page, all server calls are done via AJAX. If a session expires on the server. let's assume the user didn't close the browser, and sending some request to server using RPC, how could my server notify the application that the session has expired and that the client side portion should show the login screen again?My sample code :
ContactDataServiceAsync contactDataService = GWT
.create(ContactDataService.class);
((ServiceDefTarget) contactDataService).setServiceEntryPoint(GWT
.getModuleBaseURL()
+ "contactDatas");
contactDataService.getContact(2,
new AsyncCallback<ContactData>() {
public void onFailure(Throwable caught) {
//code to show error if problem in connection or redirect to login page
}
public void onSuccess(ContactData result) {
displayContact(result);
}
});
If session expires only it has to show login screen, otherwise it wants to show some error using Window.alert().
How to do this and what are all the codes needed in server side and client side?
You could have the server throw an AuthenticationException to the client in case the user has been logged out.
This will be catched in the callbacks onFailure method, which then can redirect the user to the login-page.
Edit:
AuthenticationException is not a standard exception of course, i was just making an example. It might be best to stick with the standard exceptions.
To try if you caught an specific exception you could use the instanceof operator
public void onFailure(Throwable e) {
if(e instanceof AuthenticationException) {
redirecttoLogin();
}
else {
showError(),
}
}
This does not directly apply to those using RPC, but for those of you who are not using RPC, you should send a HTTP 401 from the server. Then you can check that status code in your RequestBuilder callback.
Client: All Callbacks extend a Abstract Callback where you implement the onFailur()
public abstract class AbstrCallback<T> implements AsyncCallback<T> {
#Override
public void onFailure(Throwable caught) {
//SessionData Expired Redirect
if (caught.getMessage().equals("500 " + YourConfig.ERROR_MESSAGE_NOT_LOGGED_IN)) {
Window.Location.assign(ConfigStatic.LOGIN_PAGE);
}
// else{}: Other Error, if you want you could log it on the client
}
}
Server: All your ServiceImplementations extend AbstractServicesImpl where you have access to your SessionData. Override onBeforeRequestDeserialized(String serializedRequest) and check the SessionData there. If the SessionData has expire then write a spacific error message to the client. This error message is getting checkt in your AbstrCallback and redirect to the Login Page.
public abstract class AbstractServicesImpl extends RemoteServiceServlet {
protected ServerSessionData sessionData;
#Override
protected void onBeforeRequestDeserialized(String serializedRequest) {
sessionData = getYourSessionDataHere()
if (this.sessionData == null){
// Write error to the client, just copy paste
this.getThreadLocalResponse().reset();
ServletContext servletContext = this.getServletContext();
HttpServletResponse response = this.getThreadLocalResponse();
try {
response.setContentType("text/plain");
response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
try {
response.getOutputStream().write(
ConfigStatic.ERROR_MESSAGE_NOT_LOGGED_IN.getBytes("UTF-8"));
response.flushBuffer();
} catch (IllegalStateException e) {
// Handle the (unexpected) case where getWriter() was previously used
response.getWriter().write(YourConfig.ERROR_MESSAGE_NOT_LOGGED_IN);
response.flushBuffer();
}
} catch (IOException ex) {
servletContext.log(
"respondWithUnexpectedFailure failed while sending the previous failure to the client",
ex);
}
//Throw Exception to stop the execution of the Servlet
throw new NullPointerException();
}
}
}
In Addition you can also Override doUnexpectedFailure(Throwable t) to avoid logging the thrown NullPointerException.
#Override
protected void doUnexpectedFailure(Throwable t) {
if (this.sessionData != null) {
super.doUnexpectedFailure(t);
}
}