maven2-plugins/myfaces-builder-plugin/src/site/apt/components.apt

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 ------
 Creating Custom Components 
 ------
 
Creating Custom Components
 
    Any JSF Component has the following elements:
    
     * Component class file(s).
    
     * JSP tag class file(s).
    
     * Entry on faces-config.xml.
    
     * Renderer class file(s) (optional).
    
     * TLD file (optional).
    
     * facelet-taglib entry (optional).
    
     * Facelets tag handler files (optional).
    
    Keep all those files up to date is a complex task, but with 
    myfaces-builder-plugin you just need to take care about:
    
     * Component class file(s).
    
     * Renderer class file(s) (optional).
    
     * Facelets tag handler files (optional).
    
    This example shows step by step what do you need to create a custom
    component.
    
Setting up your project

    All information related can be found {{{setup.html}here}}.

Configuration files (faces-config.xml, .tld, facelets taglib)

    This {{{config-files.html}page}} shows some examples.

Writing your component class

    There are three possibilities for create a component class:
    
    * Write just one file and add all code manually (Example: t:aliasBean).
    
    * Write an abstract class, and let generate all property code, including
      saveState/restoreState methods in a concrete child class 
      (Example: almost all components in tomahawk core and sandbox).
    
    * Write an abstract class (generally package scope) and use template
      pattern. In other words, all property code is generated including
      saveState/restoreState methods in a concrete child class, but other
      code inside the abstract class is copied to the generated class.

* Write a component class manually

    In this mode, no code is generated, but the information is chained to
    other files to be generated like faces-config.xml, tlds, tag classes, etc.
    
    Below there is an example of it:
    
-------------------
/**
 * The most important points are: 
 * 
 * 1. Define componentType, componentFamily and rendererType adding its
 * constants (like below) or directly in the annotation.
 * 
 * 2. If the component has a jsp tag, define the "name" and the "tagClass"
 * If the tagClass does not exists a new file is generated if make-tags
 * goal is set on pom.xml
 * 
 */
@JSFComponent(
   name = "mycomponents:sayHello",
   clazz = "org.myorganization.component.sayhello.SayHello",
   tagClass = "org.myorganization.component.sayhello.SayHelloTag")
public class SayHello extends UIOutput
{
    public static final String COMPONENT_TYPE = "org.myorganization.SayHello";
    public static final String DEFAULT_RENDERER_TYPE = "org.myorganization.SayHelloRenderer";
    public static final String COMPONENT_FAMILY = "javax.faces.Output";

    /** ..... Some custom code goes here .... **/
}
-------------------

* Write a component class using Abstract Pattern

    The objective is create a abstract component class 
    that defines all information required to generate the concrete 
    component class. All custom code goes in the abstract class, so it
    is inherited to the child component.
    
    This pattern is preferred over template mode, because it is more simple
    to understand, but there are some cases where this mode cannot be
    applied (like in myfaces core api, where the component hierarchy cannot
    be changed).
    
    Below there is an example of it:

-------------------
/**
 * To generate component classes using abstract pattern
 * 
 * 1. Define the "clazz" file which it is generated
 * 
 * 2. Define componentType, componentFamily and rendererType adding its
 * constants (like below) or directly in the annotation.
 * 
 * 3. If the component has a jsp tag, define the "name" and the "tagClass"
 * If the tagClass does not exists a new file is generated if make-tags
 * goal is set on pom.xml
 * 
 */
@JSFComponent(
   name = "mycomponents:sayHello",
   clazz = "org.myorganization.component.sayhello.SayHello",
   tagClass = "org.myorganization.component.sayhello.SayHelloTag")
public abstract class AbstractSayHello extends UIOutput
{
    public static final String COMPONENT_TYPE = "org.myorganization.SayHello";
    public static final String DEFAULT_RENDERER_TYPE = "org.myorganization.SayHelloRenderer";
    public static final String COMPONENT_FAMILY = "javax.faces.Output";

    /**
     * User's first name.
     */
    @JSFProperty
    public abstract String getName();
}
-------------------

* Write a component class using Template Pattern

    The objective is create an abstract (generally package scoped) class
    that works as a "template".
    
-------------------
@JSFComponent(
   name = "mycomponents:sayHello",
   clazz = "org.myorganization.component.sayhello.SayHello",
   tagClass = "org.myorganization.component.sayhello.SayHelloTag")
abstract class _SayHello extends UIOutput
{
    public static final String COMPONENT_TYPE = "org.myorganization.SayHello";
    public static final String DEFAULT_RENDERER_TYPE = "org.myorganization.SayHelloRenderer";
    public static final String COMPONENT_FAMILY = "javax.faces.Output";

    /**
     * This method is copied to generated SayHello class
     **/
    public void broadcast(javax.faces.event.FacesEvent event)
        throws javax.faces.event.AbortProcessingException
    {
        //Some custom code goes here
    }
    
    /**
     * This method is not copied, but @JSFExclude works with fields too!
     **/
    @JSFExclude
    public void doSomething()
    {
        //Some never used custom code goes here
    }
    
    /**
     * User's first name.
     */
    @JSFProperty
    public abstract String getName();
}
-------------------

Generating Component Tag Classes

    The goal "make-tags" trigger component jsp tag generation. This goal
    checks if the tag class exists and if not, it creates one.

    Here there are two scenarios:
    
     * The component class inherits from jsf core UIXXXXX, so the generated 
       class inherits from javax.faces.webapp.UIComponent(EL)Tag.
     
     * The component class inherits from jsf core HtmlXXX. In this case, 
       the tag classes where your component inherits is on myfaces core 
       impl jar, so again there are three options:
       
        * Add myfaces core impl jar as compile dependency and use myfaces
          core in your web application. 
        
        * Add tomahawk core or core12 to your dependencies, where there 
          is an alternate tag hierarchy, so your components can work 
          with the reference implementation. Make sure tomahawk dependency.
          should be before myfaces core dependency in the pom, to be sure
          that tomahawk model is loaded first.
          
        * Generate a jsf html tag hierarchy in your jar. See tomahawk core
          or core12 pom for details.
    
    If you need to write some custom code on tag class, but keep some
    code generated, use abstract pattern on tag class. The properties that
    needs to be defined on abstract tag class must have inheritedTag="true",
    so there are not overriden. See t:tree component for an example.  
        
Adding a Renderer to faces-config.xml file.

    The annotations/doclets @JSFRenderer and @JSFRenderKit are used include
    renderer configuration to generated faces-config.xml files. Just add it
    to your renderer like this: 
    
---------------------------
@JSFRenderer(
   renderKitId = "HTML_BASIC",
   family = "javax.faces.Output",
   type = "org.myorganization.SayHelloRenderer")
public class SayHelloRenderer extends Renderer
{
    //Some code goes here
}
---------------------------