CODEWITHSUNDEEP
jsfjsf-2
Inquisitive
Inquisitive

Reputation: 7836

Is there a way to programatically detect when the user presses F5 button in browser?

I have a cache that I would like to invalidate whenever user issues a F5 request in the browser. I am running a JSF 2.0 application. Is there a way to do this?

Upvotes: 3

Views: 5956

Answers (4)

Igor Vuković
Igor Vuković

Reputation: 763

I found a solution that i have implemented on beyondjava

<f:metadata>
   <f:viewAction action="#{f5Detector.checkF5}" onPostBack="true"/>
</f:metadata>

Java class (just changed ManagedBean to Named)

import javax.enterprise.context.SessionScoped;
import javax.faces.component.UIViewRoot;
import javax.faces.context.FacesContext;
import javax.inject.Named;

@SessionScoped
@Named
public class F5Detector {
    private String previousPage = null;

    public void checkF5() {
        String msg = "";
        UIViewRoot viewRoot = FacesContext.getCurrentInstance().getViewRoot();
        String id = viewRoot.getViewId();
        if (previousPage != null && (previousPage.equals(id))) {
            // It's a reload event
        }
        previousPage = id;
    }
}

Upvotes: 0

pratik
pratik

Reputation: 19

I think this will be helpful you can detect any key press with key code.

Refer this link for key codes. https://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/ui/Keyboard.html

<rich:hotKey key="f5" onkeydown="if (event.keyCode == 116) return false;" handler="return false;" disableInInput="true" />
<rich:hotKey key="ctrl+R" onkeydown="if (event.keyCode == 123) return false;" handler="return false;" disableInInput="true" />
<rich:hotKey key="ctrl+f5" onkeydown="if (event.keyCode == 154) return false;" handler="return false;" disableInInput="true" />

Upvotes: 1

Stephan Rauh
Stephan Rauh

Reputation: 3160

I've uploaded a running F5 detector project on the BootsFaces demo collection on GitHub and written a short blog post. Basically, the the answer of Kolossus is correct. The ViewAction is also triggered on the first page load, so I added a couple of lines to detect that, too.

Upvotes: 0

kolossus
kolossus

Reputation: 20691

Use the FacesContext.getCurrentInstance().isPostBack() to check whether a page request is a reload of the same page. An ideal spot for this would be in a <f:viewAction/> ( new with JSF-2.2) or preRenderView event.

  1. Define the backing bean method

    public static boolean isPostback() {
   return FacesContext.getCurrentInstance().isPostback();
}

  2. Use either

    • <f:viewAction/>

      <f:metadata>
     <f:viewAction action="#{bean.isPostBack}" onPostBack="true"/>
</f:metadata>

    • f:event

      <f:metadata>
     <f:event type="preRenderView" listener="#{bean.isPostBack}"/>
</f:metadata>

OR

You could skip the whole backing bean isPostBack check altogether and directly execute the cache-clearing method directly from the page.

  • <f:viewAction/>

        <f:metadata>
         <f:viewAction action="#{bean.clearCache}" rendered="#{facesContext.postBack}" onPostBack="true"/>
    </f:metadata>

  • f:event

        <f:metadata>
         <f:event type="preRenderView" rendered="#{facesContext.postBack}" listener="#{bean.clearCache}"/>
    </f:metadata>

The benefit with this approach is that you write less code, and your cache clearing mechanism still executes only when the request is a post back

Upvotes: 3

Related Questions