Can I use multiple managed bean in the same xhtml page? [closed]

问题

when there are data that are repeated in several pages (reference example) Is that I can load into a single managed bean and I use several managed bean in the same page. What is its impact?

回答1:

Can I use multiple managed bean in the same xhtml page?

Yes, you can, I highly recommend you to try it :).

What is its impact?

This depends on the managed beans scopes. A good example is having a view to register a new address and shows the logged user info at the top of the page, similar to Amazon site where you add a new shipping address.

In this case, you can have among three managed beans:

A @SessionScoped bean that will show the logged user info. In case of amazon view, it shows only the first name.
A @ApplicationScoped bean that will provide the data for Countries. This info doesn't change too often (at least that a new country is born every day =\).
A @ViewScoped bean that will handle the request data, error messages and the registration.

A sample of the above explanation in Facelets code:

<div id="top">
    Hello #{sessionBean.user.firstName}
</div>
<div id="body">
    <h1>Add an address</h1>
    <h:form id="frmAddress">
        <h:panelGrid columns="2">
            <h:outputText value="Address" />
            <h:inputText id="txtAddress" value="#{viewBean.address}" />
            <h:outputText value="Country" />
            <h:selectOneMenu id="ddlCountry" value="#{viewBean.selectedCountry}">
                <f:selectItems value="#{applicationBean.countries}" var="country"
                    itemLabel="#{country.name}" itemValue="#{country}" />
            </h:selectOneMenu>
        </h:panelGrid>
        <h:messages id="msgErrors" />
        <h:commandButton value="Save address" action="#{viewBean.saveAddress}" />
    </h:form>
</div>

Note: this is nor a good nor a bad practice, just give it a try to see how this behaves. The impact is defined how each managed bean behaves in the page, so it will be pretty neat or a really bad experience, based on how you have defined the beans.

Related info:

Why JSF calls getters multiple times
Communication in JSF 2: Managed bean scopes

来源：https://stackoverflow.com/questions/18919545/can-i-use-multiple-managed-bean-in-the-same-xhtml-page

标签

jsf

jsf-2

managed-bean