打开页面xhtml时调用方法[primefaces]

Question

I need to call a method without clicking any Boutton but I failed to realized.

I call the method with the traditional way I create a button that has a method called

this is the code of button:

 <p:commandButton process="@form" value="ecouter"  action="#{alarmeBean.alarme}" />

but my need is to call the method when opening my page (the methode is alarme )??

Answer 1

Here's a way to call method in the backing bean at every HTTP request (including page refreshing) :

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

Otherwise, to call a method once the page is only loaded (for 1st time), you should annotate it by "post constructed" in order to invoke it in the construction's bean phase (which shouldn't be @RequestScoped to avoid sending requests to the server side, which makes page refreshing and then invokes the method again, which is not desired):

@PostConstruct
public void alarme(){
    ...
}

Answer 2

Use preRenderView like Omar said. I mean:

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

in order to avoid calling it on each poll refresh check if this is an ajax request from poll or it's a complete Get request like below in alarme method.

FacesContext fc = FacesContext.getCurrentInstance();
if (fc.getPartialViewContext().isAjaxRequest()) {
    // ignore this request, we are only interested in GET full page requests
    return;
}