Internationalised labels in JSF/Facelets

Asked 17/9, 2008 at 18:35 Answered 16/2, 2014 at 6:52

Solved java jsf internationalization facelets

Does Facelets have any features for neater or more readable internationalised user interface text labels that what you can otherwise do using JSF?

For example, with plain JSF, using h:outputFormat is a very verbose way to interpolate variables in messages.

Clarification: I know that I can add a message file entry that looks like:

label.widget.count = You have a total of {0} widgets.

and display this (if I'm using Seam) with:

<h:outputFormat value="#{messages['label.widget.count']}">
   <f:param value="#{widgetCount}"/>
</h:outputFormat>

but that's a lot of clutter to output one sentence - just the sort of thing that gives JSF a bad name.

Cyruscyst answered 17/9, 2008 at 18:35 Comment(0)

You could create your own faces tag library to make it less verbose, something like:

<ph:i18n key="label.widget.count" p0="#{widgetCount}"/>

Then create the taglib in your view dir: /components/ph.taglib.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE facelet-taglib PUBLIC "-//Sun Microsystems, Inc.//DTD Facelet Taglib 1.0//EN" "https://facelets.dev.java.net/source/browse/*checkout*/facelets/src/etc/facelet-taglib_1_0.dtd">

<facelet-taglib xmlns="http://java.sun.com/JSF/Facelet">
    <namespace>http://peterhilton.com/core</namespace>

    <tag>
        <tag-name>i18n</tag-name>
        <source>i18n.xhtml</source>
    </tag>

</facelet-taglib>

create /components/i18n.xhtml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<ui:composition xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ui="http://java.sun.com/jsf/facelets"
        xmlns:h="http://java.sun.com/jsf/html"        
    xmlns:f="http://java.sun.com/jsf/core">

    <h:outputFormat value="#{messages[key]}">
            <!-- crude but it works -->
        <f:param value="#{p0}" />
        <f:param value="#{p1}" />
        <f:param value="#{p2}" />
        <f:param value="#{p3}" />
    </h:outputFormat>

</ui:composition>

You can probably find an elegant way of passing the arguments with a little research.

Now register your new taglib in web.xml

<context-param>
<param-name>facelets.LIBRARIES</param-name>
<param-value>
        /components/ph.taglib.xml
    </param-value>
</context-param>

Just add xmlns:ph="http://peterhilton.com/core" to your views and you're all set!

Animate answered 17/3, 2009 at 23:11 Comment(1)

Good answer, and close to what we've done so far. The main problem is that you can't use it inside attribute values. – Cyruscyst 19/3, 2009 at 16:50

Since you're using Seam, you can use EL in the messages file.

Property:

label.widget.count = You have a total of #{widgetCount} widgets.

XHTML:

<h:outputFormat value="#{messages['label.widget.count']}" />

This still uses outputFormat, but is less verbose.

Kaine answered 19/9, 2008 at 8:31 Comment(1)

The only limitation of this approach is that you are tied to using this label with #{widgetCount} or you have to explicityly outject "widgetCount" to use it. – Miler 7/4, 2009 at 12:10

I've never come across another way of doing it other than outputFormat. It is unfortunately quite verbose.

The only other thing I can suggest is creating the message in a backing bean and then outputting that rather than messageFormat.

In my case I have Spring's MessageSource integrated with JSF (using MessageSourcePropertyResolver). Then, it's fairly easy in your backing beans to get parameterised messages - you just need to know which Locale your user is in (again, I've got the Locale bound to a backing bean property so it's accessible via JSF or Java).

I think parameters - particular in messages - are one thing JSF could really do better!

Bailar answered 18/9, 2008 at 14:46 Comment(0)

I have been thinking about this more, and it occurs to me that I could probably write my own JSTL function that takes a message key and a variable number of parameters:

<h:outputText value="#{my:message('label.widget.count', widgetCount)}"/>

and if my message function HTML-encodes the result before output, I wouldn't even need to use the h:outputText

#{my:message('label.widget.count', widgetCount)}

Cyruscyst answered 19/9, 2008 at 7:35 Comment(1)

If you do this and get it working, please email me teh codez ;) Seriously though, it would be a great resource if you were able to release it somewhere. – Bailar 19/9, 2008 at 8:42

You could create your own faces tag library to make it less verbose, something like:

<ph:i18n key="label.widget.count" p0="#{widgetCount}"/>

Then create the taglib in your view dir: /components/ph.taglib.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE facelet-taglib PUBLIC "-//Sun Microsystems, Inc.//DTD Facelet Taglib 1.0//EN" "https://facelets.dev.java.net/source/browse/*checkout*/facelets/src/etc/facelet-taglib_1_0.dtd">

<facelet-taglib xmlns="http://java.sun.com/JSF/Facelet">
    <namespace>http://peterhilton.com/core</namespace>

    <tag>
        <tag-name>i18n</tag-name>
        <source>i18n.xhtml</source>
    </tag>

</facelet-taglib>

create /components/i18n.xhtml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<ui:composition xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ui="http://java.sun.com/jsf/facelets"
        xmlns:h="http://java.sun.com/jsf/html"        
    xmlns:f="http://java.sun.com/jsf/core">

    <h:outputFormat value="#{messages[key]}">
            <!-- crude but it works -->
        <f:param value="#{p0}" />
        <f:param value="#{p1}" />
        <f:param value="#{p2}" />
        <f:param value="#{p3}" />
    </h:outputFormat>

</ui:composition>

You can probably find an elegant way of passing the arguments with a little research.

Now register your new taglib in web.xml

<context-param>
<param-name>facelets.LIBRARIES</param-name>
<param-value>
        /components/ph.taglib.xml
    </param-value>
</context-param>

Just add xmlns:ph="http://peterhilton.com/core" to your views and you're all set!

Animate answered 17/3, 2009 at 23:11 Comment(1)

Good answer, and close to what we've done so far. The main problem is that you can't use it inside attribute values. – Cyruscyst 19/3, 2009 at 16:50

You can use the Seam Interpolator:

<h:outputText value="#{interpolator.interpolate(messages['label.widget.count'], widgetCount)}"/>

It has @BypassInterceptors on it so the performance should be ok.

Miler answered 7/4, 2009 at 12:10 Comment(0)

You can use the Bean directly if you interpolate the messages.

label.widget.count = You have a total of #{widgetCount} widgets.
label.welcome.message = Welcome to #{request.contextPath}!
label.welcome.url = Your path is ${pageContext.servletContext}.

${messages['label.widget.count']} is enougth.

This one works great using Spring:

package foo;

import javax.el.ELContext;
import javax.el.ELException;
import javax.el.ExpressionFactory;
import javax.el.ResourceBundleELResolver;
import javax.faces.context.FacesContext;

import org.springframework.web.jsf.el.SpringBeanFacesELResolver;

public class ELResolver extends SpringBeanFacesELResolver {
    private static final ExpressionFactory FACTORY = FacesContext
            .getCurrentInstance().getApplication().getExpressionFactory();
    private static final ResourceBundleELResolver RESOLVER = new ResourceBundleELResolver();

    @Override
    public Object getValue(ELContext elContext, Object base, Object property)
            throws ELException {
        Object result = super.getValue(elContext, base, property);
        if (result == null) {
            result = RESOLVER.getValue(elContext, base, property);
            if (result instanceof String) {
                String el = (String) result;
                if (el.contains("${") | el.contains("#{")) {
                    result = FACTORY.createValueExpression(elContext, el,
                            String.class).getValue(elContext);
                }
            }
        }
        return result;
    }
}

And...

You need to change the EL-Resolver in faces-config.xml from org.springframework.web.jsf.el.SpringBeanFacesELResolver to

Regards

<el-resolver>foo.ELResolver</el-resolver>

Gooden answered 16/2, 2014 at 6:52 Comment(1)

Take care: May cause endless loop, know what you do. – Gooden 16/2, 2014 at 6:54

-1

Use ResourceBundle and property files.

Dispenser answered 18/9, 2008 at 13:7 Comment(1)

Could you explain a little more? I don't know what you mean, since OP already said he's using that. – Kaine 19/9, 2008 at 8:35

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