Java JSF 2 - 如何使用 JSF EL 从 web.xml 获取上下文参数值？
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JSF 2 - How can I get a context-param value from web.xml using JSF EL?
提问by Jim Tough
I would like to declare some constant values used by my JSF 2 webapp inside the web.xml file like so:
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：
<web-app>
<context-param>
<param-name>myconstantkey</param-name>
<param-value>some string value</param-value>
</context-param>
</web-app>
Getting these values from inside a backing bean is easy enough:
从支持 bean 内部获取这些值很容易：
FacesContext ctx = FacesContext.getCurrentInstance();
String myConstantValue =
ctx.getExternalContext().getInitParameter("myconstantkey");
How do I achieve the same thing from inside a Facelets page using JSF EL to get the value?
如何使用 JSF EL 从 Facelets 页面内部实现同样的事情来获取值？
采纳答案by Jim Tough
Steve Taylor's answer does indeed work, but there is a simpler way using the JSF EL pre-defined object initParam.
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 pre-defined object initParam。
<h:outputText value="#{initParam['myconstantkey']}" />
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.
最初这对我不起作用，因为我忘记在键名周围加上单引号并且返回一个空字符串。此解决方案还应适用于包含点字符的键值。
回答by Distortum
#{facesContext.externalContext.initParameterMap.myconstantkey}
回答by Pramod Jain
Through EL
通过EL
${initParam['myconstantkey']}
