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Use Java variable in HTML File

I made a LoginServlet with Java, that gets username and password from a database. Now I want to display the username on my website after logging in.
Servlet Code:
public class LoginServlet extends HttpServlet {
#Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String username = req.getParameter("username");
String password = req.getParameter("password");
Sql2o sql2o = DatabaseConnetcionProvider.getSql2oConnection();
User user = UserDAO.findBenutzerByUsername(username, sql2o);
if(user != null && user.getPassword().equals(password)){
UserListe.getInstance().add(user);
HttpSession session = req.getSession();
session.setAttribute("user", user);
resp.sendRedirect("/public/Home.html");
} else {
resp.sendRedirect("/public/Error.html");
}
}
}
Now I want to display the username on my Website.
I hope you can help me :)

In case of JSP you can use session implicit object
<%= ((User) session.getAttribute("user")).getUsername %>

You can retrieve value in your Home.html as below
<script type="text/javascript">
$(document).ready(function() {
userName = "{{user}}";
$("#yourFieldName").val(userName);
});
</script>

if the page is static html page,the static page can not handle the servlet page scope data,use jsp or other dynamic page to handle it,freemarker,velocity is suitable.
in jsp,you can use EL Express to show the data.the format is ${sessionScope.user}.
you should review the pageScope,requestScope,sessionScope,applicationScope concept.
sendRedirect method can cause data missing in pageScope,you should choose the right scope and the redirect or forward method,test it,please.
if the page is static page,please use AJAX to send request and handle the data,jQuery library is classic.

Interacting the JSP page with the Servlet doGet() method through AJAX call

Am doing the JAVA code found below, to call the servlet doGet() method from JSP page through AJAX call.
Here is my AJAX call..
Am sending the clicked text captured by ng-click of Angular js as a querystring to Servlet's doGet() method .
In my JSP file,
$scope.requestFunc = function (clickData) {
var urlquerystring = clickData;
jQuery.ajax({
type: 'GET',
url: "/Charts/testExecution/"+"?"+ urlquerystring,
dataType: 'html',
success: function(respnsedata)
{
window.location.assign(respnsedata);
}
});
}
In my Servlet's doGet() method,
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.err.println("In TestExecutionESO servlet..");
String teamnametextfield= req.getParameter("teamnametextfield");
System.out.println("Teamname is.."+teamnametextfield);
try {
dcmanager = DataCollectorManager.getInstance();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
String selectedteam= req.getQueryString();
String testexeclistofobjectsjson = null;
if(selectedteam!=null)
{
String release=selectedteam.replace("%20"," ").toString();
testexecutionobjlist = dcmanager.getRallyDcMgr().gettestExecutionobjlist(release);
}
Gson gson = new Gson();
testexeclistofobjectsjson = gson.toJson(testexecutionobjlist);
System.out.println(testexecutionobjlist);
System.out.println(testexeclistofobjectsjson);
req.getSession().setAttribute("testexeclistofobjectsjson", testexeclistofobjectsjson);
resp.sendRedirect("TestExecutionESO.jsp");
}
Am getting the querystring perfectly..After the processing, I will do SetAttribute() and redirect to next JSP page..
Redirect is not working..
Here is my error code,
Failed to load resource: net::ERR_TOO_MANY_REDIRECTS..
http://10.112.81.95:9000/Charts/testExecution/TestExecutionESO.jsp.... Failed to load resource: net::ERR_TOO_MANY_REDIRECTS
Please help me resolve the problem..
how to redirect to next JSP page by doing the setAttribute() .??

resp.sendRedirect("TestExecutionESO.jsp");
This is the culprit in your code. when you call sendRedirect(), it will issue a 302 response containing the location-header, URI of the new resource. When the browser sees this header, it will issue a new request for that new URI.
All of this works well for a synchronous request but in case of AJAX calls, we use an XMLHttpRequest, which will not handle redirects so well.
I'd suggest you to use a RequestDispatcher instead to forward to the JSP like this
RequestDispatcher rd = req.getRequestDispatcher("path-to-ur-jsp");
rd.forward(req,res);

unable to compare returned String from AJAX call

I am using AJAX to check a user's login details are correct. Currently if the details are correct I output "success" which is returned to the AJAX call and should be alerted. When I attempt to compare the returned String it is always falls when I try == and ===.
Here is the AJAX:
$("#loginForm").submit(function(e){
e.preventDefault(); //STOP default action
var postData = $("#loginForm").serializeArray();
var username = $("#username").val();
var password = $("#password").val();
if(username.length > 0 && password.length >){
$.ajax(
{
type: "POST",
url : "HomeController",
data : postData,
success: function(data)
{
if(data == "success"){
alert(data);
}
},
error: function(jqXHR, textStatus, errorThrown)
{
$("#loginResult").html("<p>ss"+errorThrown+textStatus+jqXHR+"</p>");
}
});
}else{
$("#loginResult").html("<p>Unable to login: ensure details are correct.</p>");
}
});
and the HomeController returning "success":
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String form = request.getParameter("form");
// check login details
if(form.equals("loginForm")){
String username = request.getParameter("username").trim();
String password = request.getParameter("password").trim();
PrintWriter out = response.getWriter();
password = loginService.hashPassword(password);
boolean isValidUser = loginService.checkUser(username, password);
if(isValidUser){
// set session
HttpSession session = request.getSession();
session.setAttribute("loggedIn", "true");
out.println("success");
}else{
out.println("Incorrect login details.");
}
}
}
I know that it is returning "success" because when I remove the if statement it alerts "success".
Why will it not successfully compare the two Strings?

Use out.print("success") instead of out.println("success") in your controller, or trim the newline from your Javascript data object.

jquery ajax call returns error on successful call to a servlet

I have a servlet that adds a user to a file on the server side.
I invoke it with a jqueries ajax call.
I can see on the server that the method is being called correctly and my user is added, but the error callback is being invoked on the jquery call. All the status text says is error.
Using firebug the response seems to be empty. Why can I not get a success jquery callback?
//Servlet Code
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String action = request.getParameter("action");
String responseStr = "";
if(action.equals("addUser"))
{
responseStr = addUser(request);
}
System.out.println("Reponse:" + responseStr);
response.setContentType("application/json");
response.setCharacterEncoding("utf-8");
response.getWriter().println(responseStr);
}
private String addUser(HttpServletRequest request) throws IOException
{
Storage s;
s = Storage.load();
String name = request.getParameter("name");
String imageUrl = request.getParameter("imageUrl");
User u = new User();
u.setName(name);
u.setImageUrl(imageUrl);
s.addUser(u);
s.save();
return "success";
}
.
//javascript code
function addUser() {
var name = $('#name').val();
var imageUrl = $('#imageUrl').val();
var url = "http://ws06525:8080/QCHounds/QCHoundServlet?action=addUser&name=${name}&imageUrl=${imageUrl}";
url = url.replace("${name}", name);
url = url.replace("${imageUrl}", imageUrl);
$('#result').html(url);
$.ajax({
url: url,
success: function( data ) {
$('#result').html(data);
},
error: function(jqXHR, textStatus, errorThrown)
{
alert("error: " + textStatus);
alert("error: " + errorThrown);
}
});
}

Aaargh! Feel like an idiot. It's a cross site scripting issue.
I was testing the call to the server from the html file on disk so my browser address was
file://projects/myproject/content/Users.html <<< Fail
instead of:
http://myboxname:8080/appname/Users.html <<< Works
The actual code is fine...

use this for learn what is the problem, it will be better for get solution i think
error: function(e){
alert(JSON.stringify(e))
}

For one thing the string "success" isn't valid json. If your ajax query is expecting json, that would fail it.
What if you returned "{ \"success\": true }" ?
EDIT
It looks like from your ajax call that the response shouldn't be json, why is your return content type json?
If it is true that firebug shows no response, your problem must be in the java code that writes the response.

Navigate to external URL from a backing bean?

I'm trying to implement proper logout for my Java EE / JSF2 application.
It requires two things:
I need to logout from JAAS and invalidate the session
I then have to navigate to an external URL to fire Siteminder logout
The Siteminder logout URL (configured on the Policy server -> I cannot change it) is outside my applications context. Eg. if my webapp URL is https://localhost:8080/sm/MyWebApp then the logout URL is https://localhost:8080/anotherwebapp/logout.html.
This is the current local logout code:
public void logout() {
System.out.println("Logging out...");
HttpServletRequest request = (HttpServletRequest)FacesContext.getCurrentInstance().getExternalContext().getRequest();
try {
request.logout();
} catch (ServletException e) {
e.printStackTrace();
}
HttpSession session = (HttpSession)FacesContext.getCurrentInstance().getExternalContext().getSession(false);
if (session != null) {
session.invalidate();
}
}
And here is the property that produces the logout URL:
public String getLogoutUrl() {
HttpServletRequest request = (HttpServletRequest)FacesContext.getCurrentInstance().getExternalContext().getRequest();
String requestServer = request.getServerName();
String requestScheme = request.getScheme();
int serverPort = request.getServerPort();
String logoutUrl = requestScheme + "://" + requestServer + ":" + Integer.toString(serverPort) + "/anotherwebapp/logout.html";
return logoutUrl;
}
However, I cannot find a JSF2 / Primefaces component that can call logout() then open the external URL. For example, if I have:
<h:outputLink value="#{authBean.logoutUrl}" onclick="#{authBean.logout()}">[Logout]</h:outputLink>
then onclick does not seem to be called.
Another way I tried was putting the external URL to the end of the logout function to have it returned as a navigation string but it is not recognized (also tried with "?faces-redirect=true"...).
Any help would be appreciated.

You can also just use ExternalContext#redirect().
public void logout() throws ServletException, IOException {
ExternalContext ec = FacesContext.getCurrentInstance().getExternalContext();
((HttpServletRequest) ec.getRequest()).logout();
ec.invalidateSession();
ec.redirect("http://example.com/anothercontext/logout");
}
No need for an intermediating page with a meta refresh.

You can create a page logout.xhtml, so the code will look like this:
public String getLogoutUrl() {
return "/logout.jsf";
}
and in the page add:
<META HTTP-EQUIV="Refresh" CONTENT="0;URL=https://localhost:8080/anotherwebapp/logout.html">