Tuesday, October 30, 2012

Registering Custom JSF Renderer

JSF has a very flexible architecture by providing hooks to plugin custom implementation for components, renderers, converters, validators etc. Today i will discuss the way to plugin own renderer without touching any other thing. Usually in every application, there are some properties which are set for ui components in order to make look & feel consistent throughout the application and these properties are set on each page for components. If we override renderer and set these properties as default properties, a lot of burden from developers end is removed. Moreover, it will also provide an easy way to change it in future at a single point instead of each page, so this is very handly thing to provide own renderers.
I am overriding a renderer for input text component of Prime faces. This renderer will not do anything special and will just print a statement on console. Here are the steps to follow:

  • First override the renderer of the component in which we want to provide custom rendering. Prime faces' User guide is an excellent reference source for each component e.g. for InutText, you will find all information about component's implementation classes and you will find there that org.primefaces.component.inputtext.InputTextRenderer is a default renderer for prime faces' input text component.



  • Create a custom renderer class which will extend above renderer and override the method in which you want to provide custom implementations. You can also download source code and can study default implementation of renderer. It will provide you good understanding how to do things. Sample implementation is given below:
     public class MyInputTextRenderer extends InputTextRenderer{
    @Override
     protected void encodeMarkup(FacesContext context, InputText inputText) throws IOException {
        System.out.println("encodemarkup");
        super.encodeMarkup(context, inputText);
    }
    }
              • Third and last thing is to register this custom renderer in jsf application. For that you will have to provide following entries in faces-config.xml:

                 
              component-family and renderer-type will help framework to understand for which component, custom renderer will be used

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