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retrive session attribute and sort it into String [duplicate]

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Show JDBC ResultSet in HTML in JSP page using MVC and DAO pattern
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I've been a PHP developer but recently need to work on some project using Google App Engine (Java). In PHP I can do something like this (in term of MVC model):
// controllers/accounts.php
$accounts = getAccounts();
include "../views/accounts.php";
// views/accounts.php
print_r($accounts);
I take a look at some demos of Google App Engine Java using Servlet and JSP. What they're doing is this:
// In AccountsServlet.java
public class AccountsServlet extends HttpServlet {
#Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String action = req.getParameter("accountid");
// do something
// REDIRECT to an JSP page, manually passing QUERYSTRING along.
resp.sendRedirect("/namedcounter.jsp?name=" + req.getParameter("name"));
}
}
Basically in the Java case it's 2 different HTTP requests (the second one being automatically forced), right? So in JSP file I can't make use of the data calculated in the Servlet.
Is there some way I can do it similar to the PHP way?

You will need to set the data retrieved in the servlet in request scope so that the data is available in JSP
You will have following line in your servlets.
List<Account> accounts = getAccounts();
request.setAttribute("accountList",accounts);
Then in JSP you can access this data using the expression language like below
${accountList}
I would use request dispatches instead of the sendRedirect as follows
RequestDispatcher rd = sc.getRequestDispatcher(url);
rd.forward(req, res);
If you can use RequestDispatcher then you can store these values in request or session object and get in other JSP.
Is there any specific purpose of using request.sendRedirect?. If not use RequestDispatcher.
See this link for more details.
public class AccountServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
List<Account> accounts = getAccountListFromSomewhere();
String url="..."; //relative url for display jsp page
ServletContext sc = getServletContext();
RequestDispatcher rd = sc.getRequestDispatcher(url);
request.setAttribute("accountList", accounts );
rd.forward(request, response);
}
}

What you want to do is first define an object to represent the information from getAccounts() - something like AccountBean.
Then in your servlets doPost or doGet function, use the request info to populate your AccountBean object.
You can then store the AccountBean object either in the request, session, or servlet context by using the setAttribute method, and forward the request to the JSP page.
The AccountBean data in your jsp page is extracted using the and tags.
Here might be an example of your servlet:
protected void doPost(HttpServletRequest req, HttpServletResponse resp) {
// get data from request querystring
String accountId = req.getParameter("accountid");
// populate your object with it (you might want to check it's not null)
AccountBean accountBean = new AccountBean(accountId);
// store data in session
HttpSession session = req.getSession();
session.setAttribute("accountBean", accountBean);
// forward the request (not redirect)
RequestDispatcher dispatcher = req.getRequestDispatcher("account.jsp");
dispatcher.forward(req, resp);
}
Then your JSP page would have the following to display the account information:
<jsp:useBean id="accountBean" type="myBeans.AccountBean" />
Your account is <jsp:getProperty name="accountBean" property="status" />

Besides what's mentioned above about using expression lang, you can also pass attributes via request itself. In Servlet's doGet(), we write something like:
Account[] accounts = AccountManager.getAccountList();
request.setAttribute("accountList", accounts );
RequestDispatcher rd = req.getRequestDispatcher(nextJSPurl);
rd.forward(req, resp);
In JSP, we can retrieve the attribute from request:
<%
Account[] accounts= (Account[])request.getAttribute("accountList");
if (accounts.length>0) {
for (Account account: accounts) {
%>
<blockquote>account name: <%= account.getName() %></blockquote>
<%
}
}
%>

import javax.servlet.http.*;
public class AccountsServlet extends HttpServlet {
public void doGet (HttpServletRequest request, HttpServletResponse response) {
try {
// Set the attribute and Forward to hello.jsp
request.setAttribute ("somename", "someValue"); // to save your temporary calculations.
getServletConfig().getServletContext().getRequestDispatcher("/namedcounter.jsp?name=" + req.getParameter("name")).forward(request, response);
} catch (Exception ex) {
ex.printStackTrace ();
}
}
}
In the above code servlet will not create 2 different requests. It will forward, also will retain all data from original request.
request.setAttribute ("somename", "someValue"); // to save your temporary calculations.

This is my understanding of your question - you want to redirect or dispatch to a new JSP page along with the data calculated in Servlet, right? To do so you need to set request attributes before dispatching the request.
You can set attributes using HttpServletRequest object (req.setAttribute("attribute name", "attribute value")). Attribute value can be any Java object.
You can retrieve the value by req.getAttribute("attribute name"). You'll also need to type cast the object while user getAttribute() function.

You can set the data inside java beans and easily access that data onto jsp page when control goes to jsp. set the date in java beans using setters get access those data onto jsp page by including that bean into jsp.
<%#page contentType="text/html"%>
<jsp:useBean id="man" class="beans.Person"/>
<jsp:setProperty name="man" property="*"/>
First Name: <jsp:getProperty name="man" property="firstName"/>
like this you can access as many properties your bean class can have.

How to get page name from WebSphere Portal page?

I am creating a portlet for WebSphere portal 8 and would like to retrieve the page name where my portlet is rendered. This is important because depending on the page, the portlet will server content differently
I've tried to use the NavigationSelectionModel API but do not think I'm using it correctly. I want this code to happen before the view is rendered and I put the code in the doView method. The problem is that I cannot cast a ServletRequest/Response because I only have the RenderRequest and RenderResponse available in the doView method.
public void doView(RenderRequest request, RenderResponse response)
throws PortletException, IOException {
// Declarations
List<ForeignAuthority> faList = new ArrayList<ForeignAuthority>();
String resp;
// Set the MIME type for the render response
response.setContentType(request.getResponseContentType());
// Check if portlet session exists
ForeignAuthoritiesPortletSessionBean sessionBean = getSessionBean(request);
if (sessionBean == null) {
response.getWriter().println("<b>NO PORTLET SESSION YET</b>");
return;
}
try{
Context ctx = new InitialContext();
NavigationSelectionModelHome home = (NavigationSelectionModelHome)
ctx.lookup("portal:service/model/NavigationSelectionModel");
if (home != null) {
NavigationSelectionModelProvider provider =
home.getNavigationSelectionModelProvider();
NavigationSelectionModel model =
provider.getNavigationSelectionModel((ServletRequest)request, (ServletResponse)response);
for (java.util.Iterator i = model.iterator(); i.hasNext(); )
{
NavigationNode node = (NavigationNode) i.next();
if (i.hasNext()) {
System.out.println(node.getObjectID().getUniqueName());
}
}
}
}catch(Exception e){
e.printStackTrace();
}
PortletRequestDispatcher rd = getPortletContext()
.getRequestDispatcher(getJspFilePath(request, VIEW_JSP));
rd.include(request, response);
}
The expected result would be to retrieve the page name or unique name of the current page that the portlet is rendered on.

You can try whether the below code snippet helps. You can get the URI value and extract the page name from it.
HttpServletRequest httpServletRequest = PortletUtils.getHttpServletRequest(renderRequest);
httpServletRequest.getRequestURI();

java - get cookie value by name in spring mvc

I'm working on a java spring mvc application. I have set a cookie in one of my controller's methods in this way:
#RequestMapping(value = {"/news"}, method = RequestMethod.GET)
public ModelAndView news(Locale locale, Model model, HttpServletResponse response, HttpServletRequest request) throws Exception {
...
response.setHeader("Set-Cookie", "test=value; Path=/");
...
modelAndView.setViewName("path/to/my/view");
return modelAndView;
}
This is working fine and I can see a cookie with name test and value "value" in my browser console. Now I want to get the cookie value by name in other method. How can I get value of test cookie?

The simplest way is using it in a controller with the #CookieValue annotation:
#RequestMapping("/hello")
public String hello(#CookieValue("foo") String fooCookie) {
// ...
}
Otherwise, you can get it from the servlet request using Spring org.springframework.web.util.WebUtils
WebUtils.getCookie(HttpServletRequest request, String cookieName)
By the way, the code pasted into the question could be refined a bit. Instead of using #setHeader(), this is much more elegant:
response.addCookie(new Cookie("test", "value"));

You can also use org.springframework.web.util.WebUtils.getCookie(HttpServletRequest, String).

private String getCookieValue(HttpServletRequest req, String cookieName) {
return Arrays.stream(req.getCookies())
.filter(c -> c.getName().equals(cookieName))
.findFirst()
.map(Cookie::getValue)
.orElse(null);
}

Spring MVC already gives you the HttpServletRequest object, it has a getCookies() method that returns Cookie[] so you can iterate on that.

private String extractCookie(HttpServletRequest req) {
for (Cookie c : req.getCookies()) {
if (c.getName().equals("myCookie"))
return c.getValue();
}
return null;
}

Cookie doesnt have method to get by value try this
Cookie cookie[]=request.getCookies();
Cookie cook;
String uname="",pass="";
if (cookie != null) {
for (int i = 0; i < cookie.length; i++) {
cook = cookie[i];
if(cook.getName().equalsIgnoreCase("loginPayrollUserName"))
uname=cook.getValue();
if(cook.getName().equalsIgnoreCase("loginPayrollPassword"))
pass=cook.getValue();
}
}

How to implement Command pattern with PRG in MVC way?

I'm working on my first web project using tomcat, jsp, servlets and log4j and I have a demo of using Command design pattern, which I'm interested in. I have one Controller which accepts doGet and doPost methods and then proccesses requests to CommandContainer which finds appropriate Command, executes it, gets path to resource and forwards the client to it.
public abstract class Command implements Serializable {
private static final long serialVersionUID = 8879403039606311780L;
public abstract String execute(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException;
}
CommandContainer which manages Commands:
public class CommandContainer {
private static final Logger LOG = Logger.getLogger(CommandContainer.class);
private static Map<String, Command> commands = new TreeMap<String, Command>();
static {
// common commands
commands.put("login", new LoginCommand());
commands.put("logout", new LogoutCommand());
commands.put("viewSettings", new ViewSettingsCommand());
commands.put("noCommand", new NoCommand());
// client commands
commands.put("listMenu", new ListMenuCommand());
// admin commands
commands.put("listOrders", new ListOrdersCommand());
LOG.debug("Command container was successfully initialized");
LOG.trace("Number of commands --> " + commands.size());
}
public static Command get(String commandName) {
if (commandName == null || !commands.containsKey(commandName)) {
LOG.trace("Command not found, name --> " + commandName);
return commands.get("noCommand");
}
return commands.get(commandName);
}
The only Controller I have:
public class Controller extends HttpServlet {
private static final long serialVersionUID = 2423353715955164816L;
private static final Logger LOG = Logger.getLogger(Controller.class);
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
process(request, response);
}
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
process(request, response);
}
private void process(HttpServletRequest request,
HttpServletResponse response) throws IOException, ServletException {
LOG.debug("Controller starts");
// extract command name from the request
String commandName = request.getParameter("command");
LOG.trace("Request parameter: command --> " + commandName);
// obtain command object by its name
Command command = CommandContainer.get(commandName);
LOG.trace("Obtained command --> " + command);
// execute command and get forward address
String forward = command.execute(request, response);
LOG.trace("Forward address --> " + forward);
LOG.debug("Controller finished, now go to forward address --> " + forward);
// if the forward address is not null go to the address
if (forward != null) {
RequestDispatcher disp = request.getRequestDispatcher(forward);
disp.forward(request, response);
}
}
}
I'am using Controller in jsp in the next way:
...
<form id="login_form" action="controller" method="post">
<input type="hidden" name="command" value="login"/>
...
</form>
And web.xml file:
<servlet>
<servlet-name>Controller</servlet-name>
<servlet-class>com.mycompany.web.Controller</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Controller</servlet-name>
<url-pattern>/controller</url-pattern>
</servlet-mapping>
I don't understand how to implement Post-Redirect-Get pattern with Command pattern, because every time request comes to controller it uses process() method and seems that it doesnt matter GET or POST is used in JSP. And then would you help understand the need of use Command pattern ? What if I will use multiple servlets like LoginServlet, LogoutServlet, ViewSettingsServlet instead of one Controller - is it would be a bad idea because then I need to hardcode them in jsp forms as actions ? All this questions just confusing me, cos I'm a starter, so please jelp me understand all this.

Well, currently, your command returns a String: the name of the JSP to forward to. If I understand correctly, you also want to be able to redirect instead of forwarding. So you need to tel the servlet that the returned value if not a view name to forward to, but a URL to redirect to.
There are various ways to do that. You could for example return an object containing the type of action to do (FORWARD or REDIRECT), and the view name or URL. Or you could return a String like redirect:/foo/bar, which means that /foo/bar is a URL to redirect to, and not a view name.
But the best solution would probably to avoid reinventing the wheel, and use an existing MVC framework rather than implementing one yourself: Spring MVC, Stripes, Struts, etc. all provide much more than what you have there, and in a much better way. In particular, using a request parameter to choose the command is not a very good choice. Using the path is a much better idea.
You could also simply use multiple servlets, which would be better than your current solution. You would lose the front controller though, which typically contains code that is common to all commands: internationalization, security checks, etc.

Java Spring MVC forward/redirect POST request using interceptor

I have a Spring MVC application which allows users to add/remove favorites via the following calls:
POST /api/users/123/favorites/456 (adds item 456 as a favorite for user 123)
DELETE /api/users/123/favorites/456 (removes item 456 as a favorite for user 123)
I'd also like to support the following 2 calls that do the exact same thing (assuming user 123 is logged in):
POST /api/users/me/favorites/456
DELETE /api/users/me/favorites/456
I've created an interceptor as shown below:
public class UserMeInterceptor extends HandlerInterceptorAdapter{
public boolean preHandle( HttpServletRequest request, HttpServletResponse response, Object handler ) throws Exception{
Integer userId = AccessControlUtil.getUserId();
String redirectUrl = request.getContextPath() + request.getRequestURI().replace( "/me/", "/" + userId + "/" );
if( redirectUrl.endsWith( "/me" ) ){
redirectUrl = redirectUrl.replace( "/me", "/" + userId );
}
response.sendRedirect( redirectUrl );
response.flushBuffer();
return false;
}
}
This approach works great, but only for GET requests. Any way I can forward/redirect a POST request and maintain all POSTed data and method type? Ideally, I want to reuse the same controller that is already defined to handle the case when the ID is passed in.

What about this approach:
#RequestMapping("/api/users/{userId}/favorites/{favoriteId}")
public String clientsByGym(#PathVariable("userId") String userId, #PathVariable("favoriteId") Long favoriteId) {
Integer theUserId = null;
if("me".equals(userId)) {
theUserId = AccessControlUtil.getUserId()
} else {
theUserId = Integer.valueOf(userId);
}
...
}
Basically, have your method accept String for userId and from there you can figure out if it is 'me' or an actual userId value. This way you don't have to mess with redirects. If you have to do this all the time, you could make a helper method like so:
public Integer getUserId(String userId) {
return "me".equals(userId) ? AccessControlUtil.getUserId() : Integer.valueOf(userId);
}

Spring MVC has two mechanisms for doing property conversion, but these those would not help in this case in a clean way - check this answer. These are not meant to be applied selectivelly only to one String parameter in particular.
The best would be to apply an aspect to the controllers and methods for which you want this functionality, see this answer for an example.