Binding a managed bean instance to composite component

问题

I have a composite component (collapsiblePanel). The component uses the "collapsible" bean to provide the toggle function. When I use the same component multiple times on a page, each instance of the component is bound to the same bean instance. How Can I achieve something like a component scoped bean?

collapsibleTemp.xhtml:

<cc:interface>
    <cc:attribute name="model" required="true">
        <cc:attribute name="collapsed" required="true" />
        <cc:attribute name="toggle" required="true"
            method-signature="java.lang.String f()" />
    </cc:attribute>
    <cc:actionSource name="toggle" />
    <cc:facet name="header" />
    <cc:facet name="body" />
</cc:interface>
<cc:implementation>
    <h:panelGroup layout="block" styleClass="collapsiblePanel-header">
        <h:commandButton id="toggle" action="#{cc.attrs.model.toggle}"
            styleClass="collapsiblePanel-img"
            image="#{cc.attrs.model.collapsed ? '/resources/images/plus.png' : '/resources/images/minus.png'}" />
        <cc:renderFacet name="header" />
    </h:panelGroup>
    <h:panelGroup layout="block" rendered="#{!cc.attrs.model.collapsed}">
        <cc:insertChildren />
        <cc:renderFacet name="body"></cc:renderFacet>
    </h:panelGroup>
    <h:outputStylesheet library="css" name="components.css" />
</cc:implementation>

The backing bean:

@ManagedBean
@ViewScoped
public class Collapsible {

    private boolean collapsed = false;

    public boolean isCollapsed() {
        return collapsed;
    }

    public void setCollapsed(boolean collapsed) {
        this.collapsed = collapsed;
    }

    public String toggle() {
        collapsed = !collapsed;
        return null;
    }

}

Using Page

<h:form id="someid">
    <jl:collapsibletemp id="collapsiblePanel1" model="#{collapsible}">
        <f:facet name="header">
            <h3>
                <h:outputText value="Collapsible information" />
            </h3>
        </f:facet>
        <f:facet name="body">
            <h:outputText value="do something....." />
        </f:facet>
        <p />
    </jl:collapsibletemp>

    <jl:collapsibletemp id="collapsiblePanel2" model="#{collapsible}">
        <f:facet name="header">
            <h3>
                <h:outputText value="Collapsible information" />
            </h3>
        </f:facet>
        <f:facet name="body">
            <h:outputText value="do some tabbing" />
        </f:facet>
        <p />
    </jl:collapsibletemp>

    <jl:collapsibletemp id="collapsiblePanel3" model="#{collapsible}">
        <f:facet name="header">
            <h3>
                <h:outputText value="Collapsible information" />
            </h3>
        </f:facet>
        <f:facet name="body">
            <h:outputText value="notice board" />
        </f:facet>
        <p />
    </jl:collapsibletemp>
</h:form>

回答1:

You can use the componentType attribute of the <cc:interface> to define a "backing component".

E.g.

<cc:interface componentType="collapsiblePanel">
    ...
</cc:interface>
<cc:implementation>
    ...
    <h:commandButton action="#{cc.toggle}" ... />
    ...
    <h:panelGroup rendered="#{!cc.collapsed}" ...>
    ...
</cc:implementation>

with just a com.example.components.CollapsiblePanel

@FacesComponent(value="collapsiblePanel") // To be specified in componentType attribute.
public class CollapsiblePanel extends UINamingContainer { // Important! Must extend UINamingContainer.

    private boolean collapsed;

    public void toggle() {
        collapsed = !collapsed;
    }

    public boolean isCollapsed() {
        collapsed;
    }

}

However, when you want to have multiple of those components, then you should declare physically separate instances of them in the view. If this needs to happen dynamically, then you need to use <c:forEach> to generate physically separate instances of them instead of <ui:repeat> with a single component. Otherwise you have to map all collapsed states by the client ID inside a Map<String, Boolean>. See for an example and more background information also Getting same instance of `componentType` in composite component on every use

来源：https://stackoverflow.com/questions/6602953/binding-a-managed-bean-instance-to-composite-component