I have a web-application where the users can be sent directly to some specific pages (such as a page where he can view or edit an item). To achieve that, we provide a specific url. These urls are located outside the current web-application (i.e. they can be present in another web-application, or in an email).
The url looks like http://myserver/my-app/forward.jsf?action=XXX¶m=YYY, where:
from-outcome of any JSF action in navigation-case in faces-config.xml.So for example, I can have these kind of urls:
http://myserver/my-app/forward.jsf?action=viewItem&actionParam=1234http://myserver/my-app/forward.jsf?action=editItem&actionParam=1234Of course, I have a Java class (bean) that will check some security constraints (i.e. is the user allowed to see / edit the corresponding item?) and then redirect the user to the correct page (such as edit.xhtml, view.xhtml or access-denied.xhtml).
Current implementation
Currently, we have a basic way to accomplish the forward. When the user clicks on the link, the following XHTML page is called:
<html>
<body id="forwardForm">
<h:inputHidden id="myAction" binding="#{forwardBean.hiddenAction}"/>
<h:inputHidden id="myParam" binding="#{forwardBean.hiddenActionParam}"/>
<h:commandButton id="forwardBtn" actionListener="#{forwardBean.doForward}" style="display: none;"/>
</body>
<script type="text/javascript">
document.getElementById('forwardForm:forwardBtn').click();
</script>
</html>
As you can see, I bind two <h:inputHidden> components in my Java bean. They will be used to store the value of both action and actionParam request parameter (using FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("actiontParam");). I also provide the doForward method that which will be called immediately when the page is rendered, which will redirect (again) the user to the real page. The method is:
public void doForward(ActionEvent evt) {
FacesContext facesContext = FacesContext.getCurrentInstance();
String redirect = // define the navigation rule that must be used in order to redirect the user to the adequate page...
NavigationHandler myNav = facesContext.getApplication().getNavigationHandler();
myNav.handleNavigation(facesContext, null, redirect);
}
This solution is working, but I have two problems with that:
So my question is how to refactor this redirection / forward feature?
Technical information
Java 1.6, JSF 1.2, Facelets, Richfaces
Set the GET query parameters as managed properties in faces-config.xml so that you don't need to gather them manually:
<managed-bean>
<managed-bean-name>forward</managed-bean-name>
<managed-bean-class>com.example.ForwardBean</managed-bean-class>
<managed-bean-scope>request</managed-bean-scope>
<managed-property>
<property-name>action</property-name>
<value>#{param.action}</value>
</managed-property>
<managed-property>
<property-name>actionParam</property-name>
<value>#{param.actionParam}</value>
</managed-property>
</managed-bean>
This way the request forward.jsf?action=outcome1&actionParam=123 will let JSF set the action and actionParam parameters as action and actionParam properties of the ForwardBean.
Create a small view forward.xhtml (so small that it fits in default response buffer (often 2KB) so that it can be resetted by the navigationhandler, otherwise you've to increase the response buffer in the servletcontainer's configuration), which invokes a bean method on beforePhase of the f:view:
<!DOCTYPE html>
<html xmlns:f="http://java.sun.com/jsf/core">
<f:view beforePhase="#{forward.navigate}" />
</html>
The ForwardBean can look like this:
public class ForwardBean {
private String action;
private String actionParam;
public void navigate(PhaseEvent event) {
FacesContext facesContext = FacesContext.getCurrentInstance();
String outcome = action; // Do your thing?
facesContext.getApplication().getNavigationHandler().handleNavigation(facesContext, null, outcome);
}
// Add/generate the usual boilerplate.
}
The navigation-rule speaks for itself (note the <redirect /> entries which would do ExternalContext#redirect() instead of ExternalContext#dispatch() under the covers):
<navigation-rule>
<navigation-case>
<from-outcome>outcome1</from-outcome>
<to-view-id>/outcome1.xhtml</to-view-id>
<redirect />
</navigation-case>
<navigation-case>
<from-outcome>outcome2</from-outcome>
<to-view-id>/outcome2.xhtml</to-view-id>
<redirect />
</navigation-case>
</navigation-rule>
An alternative is to use forward.xhtml as
<!DOCTYPE html>
<html>#{forward}</html>
and update the navigate() method to be invoked on @PostConstruct (which will be invoked after bean's construction and all managed property setting):
@PostConstruct
public void navigate() {
// ...
}
It has the same effect, however the view side is not really self-documenting. All it basically does is printing ForwardBean#toString() (and hereby implicitly constructing the bean if not present yet).
Note for the JSF2 users, there is a cleaner way of passing parameters with <f:viewParam> and more robust way of handling the redirect/navigation by <f:event type="preRenderView">. See also among others:
Edit 2
I finally found a solution by implementing my forward action like that:
private void applyForward() {
FacesContext facesContext = FacesContext.getCurrentInstance();
// Find where to redirect the user.
String redirect = getTheFromOutCome();
// Change the Navigation context.
NavigationHandler myNav = facesContext.getApplication().getNavigationHandler();
myNav.handleNavigation(facesContext, null, redirect);
// Update the view root
UIViewRoot vr = facesContext.getViewRoot();
if (vr != null) {
// Get the URL where to redirect the user
String url = facesContext.getExternalContext().getRequestContextPath();
url = url + "/" + vr.getViewId().replace(".xhtml", ".jsf");
Object obj = facesContext.getExternalContext().getResponse();
if (obj instanceof HttpServletResponse) {
HttpServletResponse response = (HttpServletResponse) obj;
try {
// Redirect the user now.
response.sendRedirect(response.encodeURL(url));
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
It works (at least regarding my first tests), but I still don't like the way it is implemented... Any better idea?
Edit This solution does not work. Indeed, when the doForward() function is called, the JSF lifecycle has already been started, and then recreate a new request is not possible.
One idea to solve this issue, but I don't really like it, is to force the doForward() action during one of the setBindedInputHidden() method:
private boolean actionDefined = false;
private boolean actionParamDefined = false;
public void setHiddenActionParam(HtmlInputHidden hiddenActionParam) {
this.hiddenActionParam = hiddenActionParam;
String actionParam = FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("actionParam");
this.hiddenActionParam.setValue(actionParam);
actionParamDefined = true;
forwardAction();
}
public void setHiddenAction(HtmlInputHidden hiddenAction) {
this.hiddenAction = hiddenAction;
String action = FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("action");
this.hiddenAction.setValue(action);
actionDefined = true;
forwardAction();
}
private void forwardAction() {
if (!actionDefined || !actionParamDefined) {
// As one of the inputHidden was not binded yet, we do nothing...
return;
}
// Now, both action and actionParam inputHidden are binded, we can execute the forward...
doForward(null);
}
This solution does not involve any Javascript call, and works does not work.
Assume that foo.jsp is your jsp file. and following code is the button that you want do redirect.
<h:commandButton value="Redirect" action="#{trial.enter }"/>
And now we'll check the method for directing in your java (service) class
public String enter() {
if (userName.equals("xyz") && password.equals("123")) {
return "enter";
} else {
return null;
}
}
and now this is a part of faces-config.xml file
<managed-bean>
<managed-bean-name>'class_name'</managed-bean-name>
<managed-bean-class>'package_name'</managed-bean-class>
<managed-bean-scope>request</managed-bean-scope>
</managed-bean>
<navigation-case>
<from-outcome>enter</from-outcome>
<to-view-id>/foo.jsp</to-view-id>
<redirect />
</navigation-case>
you should use action instead of actionListener:
<h:commandLink id="close" action="#{bean.close}" value="Close" immediate="true"
/>
and in close method you right something like:
public String close() {
return "index?faces-redirect=true";
}
where index is one of your pages(index.xhtml)
Of course, all this staff should be written in our original page, not in the intermediate.
And inside the close() method you can use the parameters to dynamically choose where to redirect.
FacesContext context = FacesContext.getCurrentInstance();
HttpServletResponse response = (HttpServletResponse)context.getExternalContext().getResponse();
response.sendRedirect("somePage.jsp");
Source: Stackoverflow.com