在c:forEach中的视图构建期间对EL的评估

问题描述

在c:forEach循环的视图构建时间内，EL语句会发生什么情况.

What happens with EL statements in a view build time in c:forEach loop.

<c:forEach var="v" values="#{bean.values}">
    <p:inputText value="#{v.name}" />
</c:forEach>

class Bean {
   public List<Pojo> getValues();
}

class Pojo {
   public void setName (String);
   public String getName();
}

如何评估此代码的渲染效果?要:

How will be this code evaluated for render? To:

 <p:inputText value="John Smith">

或

 <p:inputText value="#{pojo.name}" >

推荐答案

对于UI组件，在视图构建期间仅立即评估id和binding属性.所有其他属性都被推迟. IE.他们将获得 ValueExpression 的实例(或 MethodExpression )，而不是立即进行评估价值.在每个getValue()/setValue()调用中都会重新评估ValueExpression.

For UI components, only id and binding attributes are immediately evaluated during view build time. All other attribtues are deferred. I.e. they will get an instance of ValueExpression (or MethodExpression) instead of the immediately evaluated value. The ValueExpression is re-evaluated on every individual getValue()/setValue() call.

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