JSF 2 - How can I get a context-param value from web.xml using JSF EL?

I would like to declare some constant values use开发者_如何学JAVAd 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>

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

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?

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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']}" />

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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#{facesContext.externalContext.initParameterMap.myconstantkey}

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Through EL

${initParam['myconstantkey']}