JSF 2 - 如何使用JSF EL从web.xml获取上下文参数值？ [英] JSF 2 - How can I get a context-param value from web.xml using JSF EL?

问题描述

我想在web.xml文件中声明我的JSF 2 webapp使用的一些常量值，如下所示：

I would like to declare some constant values used by my JSF 2 webapp inside the web.xml file like so:

<web-app>
    <context-param>
        <param-name>myconstantkey</param-name>
        <param-value>some string value</param-value>
    </context-param>
</web-app>

从支持bean中获取这些值非常简单：

Getting these values from inside a backing bean is easy enough:

FacesContext ctx = FacesContext.getCurrentInstance();
String myConstantValue =
    ctx.getExternalContext().getInitParameter("myconstantkey");

如何使用JSF EL在Facelets页面内实现同样的功能？

How do I achieve the same thing from inside a Facelets page using JSF EL to get the value?

推荐答案

史蒂夫泰勒的答案确实有效，但有一种更简单的方法使用JSF EL预定义对象 initParam 。

Steve Taylor's answer does indeed work, but there is a simpler way using the JSF EL pre-defined object initParam.

<h:outputText value="#{initParam['myconstantkey']}" />

最初这对我不起作用，因为我忘记在密钥名称周围加上单引号回来了一个空字符串。此解决方案还应使用包含点字符的键值。

Originally this wasn't working for me because I forgot to put the single quotes around the key name and was getting back an empty string. This solution should also work with key values that contain dot characters.

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