JSF Tip #34 - Override JSF renderer and create a new tag for it

When I posted JSF Tip #32 - Override a JSF renderer Twitter user @john_waterwood asked me how you would define a new tag for an existing component and the overridden renderer. Well it is fairly easy, see the 2 steps below!

1. Create your renderer
2. Register it

Creating your renderer

    package org.glassfish.jsf.overrideRenderer;

    import java.io.IOException;
    import javax.faces.component.UIComponent;
    import javax.faces.component.UIOutput;
    import javax.faces.context.FacesContext;
    import javax.faces.context.ResponseWriter;
    import javax.faces.render.Renderer;

    @FacesRenderer(rendererType="myText")
    public class MyTextRenderer extends Renderer {

        @Override
        public void encodeBegin(FacesContext context, UIComponent component) throws IOException {
        }

        @Override
        public void encodeChildren(FacesContext context, UIComponent component) throws IOException {
        }

        @Override
        public void encodeEnd(FacesContext context, UIComponent component) throws IOException {
            ResponseWriter responseWriter = context.getResponseWriter();
            UIOutput output = (UIOutput) component;
            String value = "Let's be funny: " + output.getValue().toString();
            responseWriter.writeText(value, null);
        }
    }
        

Register it

    <?xml version="1.0" encoding="UTF-8"?>
    
    <facelet-taglib xmlns="http://java.sun.com/xml/ns/javaee" 
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
       xmlns:xi="http://www.w3.org/2001/XInclude" 
       xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facelettaglibrary_2_0.xsd" 
       version="2.0">
        <namespace>mynamespace</namespace>
        <composite-library-name>m</composite-library-name>
        <tag>
            <tag-name>myOutputText</tag-name>
            <component>
                <component-type>javax.faces.HtmlOutputText</component-type>
                <renderer-type>myText</renderer-type>
            </component>
         </tag>
    </facelet-taglib>
        

Posted November 7, 2013

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