Before using this, you should’ve designed your domain model to extend a Base Class (do it, it’s a good practice). In my case, I have BaseIdentityEntity which has an @Id, @Version properties

import java.io.Serializable;

import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.ConverterException;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import org.apache.log4j.Logger;
import org.springframework.stereotype.Service;

import xxx.model.BaseIdentityEntity;

/**
* Generic Entity Converter for any Entity that extends BaseIdentityEntity
*
*/
@Service("entityConverter")
public class EntityConverter implements Converter, Serializable {
	static Logger log = Logger.getLogger(EntityConverter.class);
	private static final long serialVersionUID = -5137676309479323480L;

	@PersistenceContext
	protected EntityManager entityManager;

	@SuppressWarnings("unchecked")
	public Object getAsObject(FacesContext facesContext, UIComponent component,
			String value) throws ConverterException {
		BaseIdentityEntity entity;
		if (value == null) {
			entity = null;
		} else {
			Integer id = new Integer(value);
			entity = (BaseIdentityEntity) entityManager.find(getClazz(
					facesContext, component), id);
			if (entity == null) {
				log.debug("There is no entity with id:  " + id);
				//throw new IllegalArgumentException("There is no entity with id:  " + id);
			}
		}
		return entity;
	}

	public String getAsString(FacesContext facesContext, UIComponent component,
			Object value) throws ConverterException {
		if (value != null && !(value instanceof BaseIdentityEntity)) {
			throw new IllegalArgumentException(
					"This converter only handles instances of BaseIdentityEntity");
		}
		if (value == null) {
			return "";
		}
		if (value instanceof String) {
			return (String) value;
		}
		BaseIdentityEntity entity = (BaseIdentityEntity) value;
		return entity.getId() == null ? "" : entity.getId().toString();
	}

	// Gets the class corresponding to the context in jsf page
	@SuppressWarnings("unchecked")
	private Class getClazz(FacesContext facesContext, UIComponent component) {
		return component.getValueExpression("value").getType(facesContext.getELContext());
	}

}

You don’t have to add any configuration in the taglibs since Spring’s @Service tag makes the converter a managed bean and you can reference it directly in jsf.

Usage: (Using JSF tomahawk here, but works for any jsf component library)

<h:selectOneMenu value="#{mycontroller.foo}" converter="#{enumConverter}">
	<h:selectItems value="#{mycontroller.foos}" var="element"
	itemLabel="#{element}" itemValue="#{element}" />
</h:selectOneMenu>

Here are the steps for creating a simple tag – iconButton, which decorates a button with an icon image and other misc useful attributes.

taglib descriptor: your-taglib.xml (place it in WEB-INF)

<?xml version="1.0"?>
<!DOCTYPE facelet-taglib PUBLIC "-//Sun Microsystems, Inc.//DTD Facelet Taglib 1.0//EN" "facelet-taglib_1_0.dtd">
<facelet-taglib>
    <namespace>http://yourUrlHere</namespace>
    <tag>
       <tag-name>iconButton</tag-name>
       <source>view/tags/iconButton.xhtml</source>
     </tag>
</facelet-taglib>

iconButton.xhtml

<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">

<button title="#{title}" class="#{styleClass}"
    onclick="#{empty onclick ? '' : onclick}">
    <img src="#{iconSrc}" border="0" align="top"
    style="padding-top:1px;padding-bottom:1px;"/>
   #{text}
</button>
</ui:composition>

Usage (in other facelets)
somepage.xhtml

<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"
    xmlns:myTags="http://yourUrlHere"

    <myTags:iconButton title=" Search "
                                styleClass="iconButton" style="vertical-align:top;"
                                iconSrc="./img/magnifying-glass.png"
                                text="Search "/>

Note the inclusion of the namespace (“yoururl”) above.

web.xml

<context-param>
    <param-name>facelets.LIBRARIES</param-name>
    <param-value>/WEB-INF/tomahawk-taglib.xml;/WEB-INF/my-taglib.xml</param-value>
</context-param>

You may get the following error: -

Caused by: java.io.FileNotFoundException: <jboss-home>\bin\facelet-taglib_1_0.dtd

That’s probably because you haven’t declared the taglib in WEB-INF, as shown above.

public class DateConverter implements Converter, Serializable {
	public Object getAsObject(FacesContext context, UIComponent component, String value) {
	    java.sql.Date sqlDate = null;
	    Calendar cal = null;

	    if (value != null && value.length() > 0) {
	      DateFormat df = new SimpleDateFormat("dd-MMM-yy");

	      try {
	    	  Date utilDate = df.parse(value);
	          cal = new GregorianCalendar();
	          cal.setTime(utilDate);
	    	  sqlDate = new java.sql.Date(utilDate.getTime());
	      }
	      catch (ParseException e) {
	        throw new ConverterException(e);
	      }
	    }
	    return sqlDate;
	  }

	  public String getAsString(FacesContext context, UIComponent component, Object value) {
	    String dateString = null;
	    if (value != null) {
	      if (value instanceof String) {
	        dateString = (String) value;
	      }
	      else {
	        DateFormat df = new SimpleDateFormat("dd-MMM-yy");
	        if (value instanceof java.sql.Date) {
	        	Date date = new Date(((java.sql.Date)value).getTime());
	 	        dateString = df.format(date);
	        }
	      }
	    }
	     return dateString;
	  }
}