jsf difference between implicit objects cc and component

Maybe this is a dumb question, but I use

cc

to refer to the composite component, for instance cc.attrs.randomAttr but I have also seen the

component

implicit object and I have used it because I was told to but I don't really understand what it is for. Can anyone explain please?

cc refers to the top level composite component that is being processed at the time of evaluation.

component simply is the ui component being processed.

So when inside a composite component, cc refers to the 'parent' component, while component when used on an individual component refers to that particular instance. Or for simple cases:

cc == component.getCompositeComponentParent(component), with component being a component of which the composite component is build.

E.g. consider the following composite component:

<html 
    xmlns="http://www.w3.org/1999/xhtml"
    xmlns:h="http://java.sun.com/jsf/html"    
    xmlns:cc="http://java.sun.com/jsf/composite"
>
    <cc:interface/>

    <cc:implementation>

        <h:outputText value="Own ID: #{component.id}, parent composite ID: #{cc.id}" /> <br/>
        <h:outputText value="Own ID: #{component.id}, parent composite ID: #{cc.id}" />

    </cc:implementation>    

</html>

Using this on a Facelet will print 2 different "own" IDs, namely the ones of the two outputText components, while the composite ID will be the same on both lines.

Note that things may become a little more complicated when multiple nestings of composite components are involved.

来源：https://stackoverflow.com/questions/5124961/jsf-difference-between-implicit-objects-cc-and-component

标签

java

jsf

jsf-2

composite-component