jsf-2 - 如何检查复合组件中是否存在可选属性

Question

我需要验证是否在我的复合组件中传递了可选属性。我怎样才能做到这一点？

<composite:interface>
    <composite:attribute name="attr1" />
    <composite:attribute name="attr2" required="false" /> <!-- means OPTIONAL -->
</composite:interface>
<composite:implementation>
    <!-- How I can verify here whether attr2 is present or not whenever this component is used? -->
</composite:implementation>

设置 default归因于 xxx为 <composite:attribute>不是我要找的。

Answer 1

您可以检查是否 #{not empty cc.attrs.attr2}计算结果为 true .

例如内rendered任意组件的属性:

<composite:implementation>
    <h:panelGroup rendered="#{not empty cc.attrs.attr2}">
        Attribute attr2 is not empty!
    </h:panelGroup>
</composite:implementation>