是否将 f:event 放在 f:metadata 中是否重要? [英] Does it matter whether place f:event inside f:metadata or not?

问题描述

w.r.t.如何使用 f 对 GET 请求执行操作:视图参数?

<f:metadata>
    <f:viewParam name="id" value="#{tInputBean.id}" />
    <f:event type="preRenderView" listener="#{tInputBean.init}" />
</f:metadata>

我想知道是否将 preRenderView f:event 放在 f:metadata 中是否重要.我查看了 Java EE6 教程、Java Server Faces 2.0 完整参考和 Core JSF2，没有一个在 f:metadata 中有 f:event 的示例，但我在网上看到了很多这样的示例.

I'm interested to know whether it matters if a preRenderView f:event is placed inside the f:metadata or not. I've checked the Java EE6 tutorial, Java Server Faces 2.0 Complete Reference, and Core JSF2, and none of them have examples of f:event inside f:metadata, but I've seen lots of examples online like this.

JSF2 Compl.Ref 说 p.540

JSF2 Compl.Ref says p.540

f:metadata 标签封装了用于指定的元素集Facelet 视图的元数据，因此必须是f:view 标记并且可能不会出现在模板中.从 JSF2.0 开始，唯一的这个标签的作用是封装f:viewParam标签.

The f:metadata tag encapsulates the set of elements used to specify the metadata for a Facelet view, and therefore must be a child of the f:view tag and may not appear in a template. As of JSF2.0, the only purpose of this tag is to encapsulate f:viewParam tags.

将 f:event(通常用于支持 f:viewParam)放在 f:metadata 中是否有特殊意义，还是只是为了在视觉/逻辑上帮助将它与 f:viewParam 分组?

Does placing the f:event (often used to support an f:viewParam) inside the f:metadata have a special meaning, or is it just to help group it alongside the f:viewParam visually/logically ?

推荐答案

不， 不是严格要求放在 .它可以连接到任何组件.当你有一堆 <f:viewParam>s 并且想要钩一个 在设置所有这些视图参数后调用操作.它甚至可以放在那些 <f:viewParam> 的外面/之前，但它使代码不再是自文档化的.

No, the <f:event> is not strictly required to be placed inside <f:metadata>. It can be attached to any component. It's indeed for pure self-documentary purposes placed inside the <f:metadata> whenever you have a bunch of <f:viewParam>s and would like to hook a <f:event> to invoke an action after all those view parameters have been set. It can even be placed outside/before those <f:viewParam>s, but it makes the code not more self-documenting.

请注意，在即将发布的 JSF 2.2 中，将引入一个新的 <f:viewAction> 标记，该标记又应该替换 <f:event type="preRenderView"> 在 .

Note that in the upcoming JSF 2.2, a new <f:viewAction> tag will be introduced which in turn is supposed to replace the <f:event type="preRenderView"> in the <f:metadata>.

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