Can any one please describe me when the objects of ActionMapper, ActionProxy, ActionInvocation, ActionContext are created in a Struts2 application. As I am new to Struts2 framework, I am very much confused about the scopes of these objects.
The ActionMapper is created on startup, it has a singleton scope.
The ActionContext is created by the Dispatcher in preparing an action to execute, it's ThreadLocal, and it doesn't have any scope.
When action is executing the ActionInvocation and ActionProxy are created that also don't have a scope.
You can see this on a big picture of Struts2 architecture.
Related
Can somebody explain the role of the Action Mapper in Struts 2?
The role of ActionMapper interface in Struts2 framework is to extract mapping from the request's URL.
When given an HttpServletRequest, the ActionMapper may return null if no action invocation request matches, or it may return an ActionMapping class that describes an action invocation for the framework to try.
You can read more about this feature here.
Th first method returns a mapping to try, it doesn't guarantee that this action will be executed.
The ActionMapping returned by the action mapper contains all necessary information to invoke an action if there's an action config corresponding to this mapping is available in runtime configuration.
Different implementation of this interface can be used to override the default behavior for mapping URLs to actions in Struts2.
I've looked at some other threads here and I think I have the general idea of how to use a SessionScoped bean for maintaining a user's logged in state. However, as I am relatively new to JSF 2, I am trying to figure out the best way to use the bean during login and on subsequent pages to render a header/footer (using same page template, but different menus/links depending on login state and non-logged in state).
I have a typical JSF2 login form that calls a backing bean (request scoped) login() method. All of that works, and I am going to tie it in to the container security soon as I have a little more time to work on and figure that part out (realms, roles, etc).
In the old pre-JSF (jsp/struts) days, upon login, I'd add an object, usually a user ID Long value that would be easy to replicate across a cluster of sessions and restore a full user object from. This kept the httpsession data minimal (one Long value per user), and regardless of what server a user was routed, I could determine they were logged in and pull up their user object and go from there.
With JSF, I am not sure the right way to do this. I have a SessionScoped bean with a Long userid property. Upon the login() method succeeding, I use the ExternalContext to add the attribute of the SessionScoped object, something like:
User user = loginBean.login(username, password);
Session session = new Session();
session.setUserid(user.getId());
externalContext.getSessionMap().put("usersession", session);
externalContext.redirect(originalURL);
The Session is the SessionScoped bean, and it's CDI name is usersession. I hope that is the right way to stick the bean into the HttpSession so it can be used on pages, etc with EL.
The first thing I am not sure of is because the bean is SessionScoped, do I need to put it into the session after creating it in the above code? Or is that done automatically upon creation for me since it's scoped as session?
The second question is.. being picky that I am, I don't want a Session object in the session until the user logs in, even if the userid is null. So on a xhtml page, if I have something like:
<h:panelGroup render="#{usersession.loggedin}"...>
Will that create and put the Session bean into the session the first page that uses that? Or will that Session object not be put into the HttpSession until I do so with my code above? My guess is, if it gets put into the session upon creation, then the use of it on any page will create it and stick it in the session. I am less bothered by this..the object with just the Long property is very little memory use per user on the system, but like I said, I am being picky and more so wanted to understand exactly when a SessionScoped object gets stored into the session.
Thanks.
The first thing I am not sure of is because the bean is SessionScoped, do I need to put it into the session after creating it in the above code? Or is that done automatically upon creation for me since it's scoped as session?
The managed bean is autocreated in the given scope if referenced for the first time in EL by #{beanName} while it's not in the scope yet. So, no, you don't need to do it yourself. Just inject it as managed property in your login bean.
#ManagedProperty("#{usersession}")
private Session session;
// ...
User user = loginBean.login(username, password);
session.setUserid(user.getId());
externalContext.redirect(originalURL);
Will that create and put the Session bean into the session the first page that uses that? Or will that Session object not be put into the HttpSession until I do so with my code above?
It will do that once you reference it for the first time in EL by #{beanName}.
Unrelated to the concrete question, another way is
User user = loginBean.login(username, password);
externalContext.getSessionMap().put("user", user);
externalContext.redirect(originalURL);
and check for the logged-in user as follows
<h:panelGroup rendered="#{not empty user}">
See also:
Performing user authentication in Java EE / JSF using j_security_check
Please note: This question is about CDI scopes as we are using CDI scopes in the app and not JSF scopes.
1) Controller Bean (TestController.java) which is in RequestScoped (enterprise context) is called index_cut.xhtml, when we come for first time on this page.
2) On button “Load”, we load the following method to populate the sapFinancialPeriodList which works fine and displays the data
3) After changing the content on the page and submitting, the sapFinancialPeriodList appears as NULL in the following method –
Any suggestions?
Your bean is request scoped and you're loading the data model on action only instead of on (post)construction. When the HTTP response after the action which loaded the data is finished, then the bean is garbaged. The subsequent request would get a brand new instance of the bean with all properties set to default. However, as the same data model isn't been preserved during (post)construct, it remains empty.
In JSF2 you'd solve this with using #ViewScoped. This way the bean will live as long as you're interacting with the same view by postbacks (which return null or void).
In CDI you'd need to solve this using #ConversationScoped, which in turn requires some additional #Inject Conversation boilerplate, complete with begin() and end() calls at the right moments. For a concrete example, see also What scope to use in JSF 2.0 for Wizard pattern?.
An alternative is to pass the parameters responsible for creating the data model to the subsequent request via <f:param> in the command link/button as follows
<h:commandButton value="save" ...>
<f:param name="period" value="#{bean.period}" />
</h:commandButton>
and then recreate exactly the same data model in (post)constructor of the request scoped bean as follows
String period = FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("period");
List<SapFinancialPeriod> sapFinancialPeriodList = someservice.list(period);
(the above is by the way nicer to solve with #ManagedProperty if you were using standard JSF; as far as I know CDI doesn't have an annotation which enables you to set a HTTP request parameter as a bean property)
See also:
How to choose the right bean scope?
Unrelated to the concrete problem, the upcoming JSF 2.2 solves this functional requirement in a nicer way using the new "Faces Flow" feature with the new #FlowScoped annotation and the new xmlns:j="http://java.sun.com/jsf/flow" tags.
Hi I have Question we can use both Action Context and Servlet Action Context to access the resources But why Struts2 people implemented two if they work same
They don't work the same; one has web-app-specific functionality.
XWork is not a web app framework--hence the ActionContext. WebWork/Struts 2 added web-specific functionality, hence ServletActionContext, which is a subclass of ActionContext, and adds web-related stuff.
As quoted in:
Servlet Action Description
Servlet Action Context is a sub class of Action Context.
"ServletActionContext is Web-specific context information for actions".This class adds access to web objects like servlet parameters, request attributes and things like the HTTP session. In simple terms one can say Action Context is generic while the servlet action context is more specific in terms of its usage
For Example: GenericServlet and HttpServlet; GenericServlet is for servlets that might not use HTTP, like for instance FTP servlets etc. while HttpServlet is more specific.
I'm very new to ASP.NET MVC so I hope my question makes sense. I'm using POCO objects as my model. It's my understanding that when the form is submitted MVC can create a new instance of my business object and fill the properties from the form automatically.
I use dependency injection so I create new instances using code like the following:
DependencyResolver.Current.CreateInstance(Of IBusObject)
How can I get ASP.NET MVC to call this method instead of trying to create a new instance by using the "new" keyword on the concrete class?
Looking at the MVC source code it will not use dependency resolution when creating an instance of the model type, so you can't get what you want out of the box, but you could easily achieve what you want by creating your own model binder which is DependencyResolver aware.
You could write a custom model binder deriving from the default model binder and override the CreateModel method to supply your custom instance.