The major benefit of the JSF framework is a component based architecture. The component in JSF is not just a set of HTML code rendered and interpreted by a browser. The JSF component is a composition of a client-side widget coupled with the server-side object that represents component behavior including data validation, events handling, business layers bean binding, etc.
In contrast to a page-oriented development approach, JSF allows to use a component-oriented paradigm to build a well-designed, highly customizable UI interface based on reusable components.
However, there is not yet enough sets of rich components on the market that might enable the rapid application developments. One of important problems is a long and very complicated process of the component creation. Even the very primitive JSF component requires to write the UIComponent class, Renderer class, Tag class and a faces configuration file (faces-config.xml).
In order to use the component library in a Facelets environment, you should add the *.taglib.xml file to this checklist.
Creation of the rich component takes even more time. You have to provide the ListenerTagHandler class, a class for creating a listener interface, an event processing method name in a listener interface, an event class, render specific classes for each possible render kit used with the component.
Therefore, the process of JSF component creation is pretty complicated but repeatable. Jonas Jacobi and John R. Fallows in their "Pro JSF and Ajax Bulling Rich Internet Components" book describe the process in details. This description and used approaches are very similar to our own experience and have been used as a methodology for Component Development Kit (CDK) - a sub-project of RichFaces that allows you to easily create rich components with built-in Ajax support.
The significant features of the Component Development Kit (CDK) are:
Quick development start. A new component development starts from a pre-generated component project template. It contains the whole required infrastructure and necessary files generated. It's necessary only to have a Maven installed. All other required stuff will be loaded and configured automatically.
Declarative approach for a component development. It's necessary only to specify meta-data and a code specific for your component. All other required artifacts are generated for you.
Independent development life-cycle. Component Development Kit (CDK) presumes development of each component isolated from each other with further assembling them into the component library. Hence, this allows to organize a continuous process when one component is already in production condition, but another is just started.
Possibility to create a first-class rich components with built-in Ajax functionality and add Ajax capability to the existing JSF applications.
Facility for automatic testing. At the moment of generating the initial project structure, the Unit Test classes are also generated. The RichFaces also provides the Mock-test facility that allows to emulate a run-time environment and automatically test the components before their are gathered into the result library.
Optimization for different JSF implementations. As soon as the most part of a result code is generated, the Component Development Kit (CDK) becomes able to generate an implementation specific code along with a universal code. It makes sense if it's necessary to optimize a result code using features specific for the particular implementation. For example, for using with JSF 1.2 only.
Create a modern rich user interface look-and-feel with JSP-like templates and skins-based technology. RichFaces comes with a number of predefined skins to get you started, but you can also easily create your own custom skins.
This document is aimed to describe components development with the Component Development Kit (CDK) and its features.
In order to be successful in Component Development Kit (CDK) usage and components development, it's necessary to be acquainted with Java Server Faces and RichFaces framework. To read more on these topics, please, follow the links:
In order to start working with the Component Development Kit (CDK) and to create your rich component, it's necessary to have the following installed:
Browser (on client side)
After the Maven is installed you should configure it. In this case, please, go to the directory where you've just installed Maven, open a conf/settings.xml file for editing and add to the profiles section this code:
...
<profile>
<id>cdk</id>
<repositories>
<repository>
<id>maven2-repository.dev.java.net</id>
<name>Java.net Repository for Maven</name>
<url>http://download.java.net/maven/1</url>
<layout>legacy</layout>
</repository>
<repository>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>false</enabled>
<updatePolicy>never</updatePolicy>
</snapshots>
<id>repository.jboss.com</id>
<name>Jboss Repository for Maven</name>
<url>http://repository.jboss.com/maven2/</url>
<layout>default</layout>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>maven.jboss.org</id>
<name>JBoss Repository for Maven Snapshots</name>
<url>http://snapshots.jboss.org/maven2/</url>
<releases>
<enabled>false</enabled>
</releases>
<snapshots>
<enabled>true</enabled>
<updatePolicy>always</updatePolicy>
</snapshots>
</pluginRepository>
<pluginRepository>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>false</enabled>
<updatePolicy>never</updatePolicy>
</snapshots>
<id>repository.jboss.com</id>
<name>Jboss Repository for Maven</name>
<url>http://repository.jboss.com/maven2/ </url>
<layout>default</layout>
</pluginRepository>
</pluginRepositories>
</profile>
...
In order to activate new profile, please, add the following after the profiles section:
...
<activeProfiles>
<activeProfile>cdk</activeProfile>
</activeProfiles>
...
Note:
In order to work with Maven from Eclipse, it's possible to download and install the Maven plugin. Please, follow the instruction at Eclipse plugins for Maven page
The environment is set up now to use the Component Development Kit (CDK).
We are going to create two components throughout the RichFaces CDK Developer Guide, but at first you need take the following steps in order to set up the Project and create your library:
Create a new directory where all the components will be stored (for example Sandbox).
Create a file named pom.xml in the directory with the following content:
...
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.mycompany</groupId>
<artifactId>sandbox</artifactId>
<url>http://mycompany.org</url>
<version>1.0-SNAPSHOT</version>
<packaging>pom</packaging>
<dependencies>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.4</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jsp-api</artifactId>
<version>2.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.1</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.faces</groupId>
<artifactId>jsf-api</artifactId>
<version>1.2_07</version>
</dependency>
<dependency>
<groupId>javax.faces</groupId>
<artifactId>jsf-impl</artifactId>
<version>1.2_07</version>
</dependency>
<dependency>
<groupId>javax.el</groupId>
<artifactId>el-api</artifactId>
<version>1.0</version>
</dependency>
<dependency>
<groupId>el-impl</groupId>
<artifactId>el-impl</artifactId>
<version>1.0</version>
</dependency>
<dependency>
<groupId>javax.annotation</groupId>
<artifactId>jsr250-api</artifactId>
<version>1.0</version>
</dependency>
<dependency>
<groupId>org.richfaces.ui</groupId>
<artifactId>richfaces-ui</artifactId>
<version>3.2.1.GA</version>
</dependency>
</dependencies>
</project>
...
Close the file
Here are some of these elements with descriptions:
Table 3.1. The POM elements
| Element | Description |
|---|---|
| groupId | Prefix for the Java package structure of your library |
| url | Namespace for your library to be used in the TLD file |
| version | Version of your library |
We a going to create the <inputDate> component that can take a value, process that value, and then push it back to the underlying model as a strongly typed Date object.
The <inputDate> component allows to attach a converter in order to set the desired date format such as mm/dd/yyyy. So the component could convert and validate the date entered by user.
At first we need to create a project for the component itself. In the library directory Sandbox you just created, launch the following command (all in one line):
mvn archetype:create -DarchetypeGroupId=org.richfaces.cdk -DarchetypeArtifactId=maven-archetype-jsf-component -DarchetypeVersion=3.2.1.GA -DartifactId=inputDate
As is easy to see a new directory with the name inputDate will be created. It does not have any components in it yet, but it has this predefined structure:
Here are main directories with descriptions:
Table 4.1. The project structure
| Directory | Description |
|---|---|
| src/main/config | Contains the metadata for the components |
| src/main/java | Contains Java code (both pre-generated and created by you) |
| src/main/resources | Used to store resource files, such as pictures, JavaScript and CSS files |
| src/main/templates | Used to contain the JSP-like templates that define the component layout |
It is necessary to extend predefined structure with the following directories:
Table 4.2. The project structure
| Directory | Description |
|---|---|
| src/main/config/resources | Contains the resource-config.xml file for the resources registration |
| src/main/java/org/mycompany/renderkit | Contains Renderer Base class |
| src/main/resources/org/mycompany/renderkit/html/css | Used to store CSS files |
| src/main/resources/org/mycompany/renderkit/html/images | Used to store images |
| src/main/resources/org/mycompany/renderkit/html/scripts | Used to store JavaScript files |
| src/main/templates/org/mycompany | Used to contain the JSP-like template |
Now you should add maven-compiler-plugin to the plugins section in the inputDate/pom.xml file:
...
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<inherited>true</inherited>
<configuration>
<source>1.5</source>
<target>1.5</target>
</configuration>
</plugin>
...
Finally your inputDate/pom.xml should look like this one:
<?xml version="1.0"?>
<project>
<parent>
<artifactId>sandbox</artifactId>
<groupId>org.mycompany</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<groupId>org.mycompany</groupId>
<artifactId>inputDate</artifactId>
<name>inputDate</name>
<version>1.0-SNAPSHOT</version>
<build>
<plugins>
<plugin>
<groupId>org.richfaces.cdk</groupId>
<artifactId>maven-cdk-plugin</artifactId>
<version>3.2.1.GA</version>
<executions>
<execution>
<phase>generate-sources</phase>
<goals>
<goal>generate</goal>
</goals>
</execution>
</executions>
<configuration>
<library>
<prefix>org.mycompany</prefix>
<taglib>
<shortName>inputDate</shortName>
</taglib>
</library>
</configuration>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<inherited>true</inherited>
<configuration>
<source>1.5</source>
<target>1.5</target>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.richfaces.framework</groupId>
<artifactId>richfaces-impl</artifactId>
<version>3.2.1.GA</version>
</dependency>
</dependencies>
</project>
Let's create a skeleton for the <inputDate> component.
You need to go to the inputDate directory and then launch the following command:
mvn cdk:create -Dname=inputDate
As a result three artifacts will be created:
An XML configuration file for the metadata
A UI class
A JSP-like template
In order to build the component you should stay in the inputDate directory and launch the following command:
mvn install
This command generates and compiles the library and then creates a result JAR file. A directory named target will be created along with a src directory. If you get a file named target/inputDate-1.0-SNAPSHOT.jar, everything is set up successfully.
If you want to rebuild the component you could use the following command:
mvn clean install
It is a good idea to create at first a prototype of the intended markup. You will find out which markup elements the component has to generate and also which renderer-specific attributes are needed in order to parameterize the generated markup.
The
<inputDate>
component consists of an HTML form <input> element, an
<img> element, and <div> element:
...
<div title="Date Field Component">
<input name="dateField" value="01 January 2008" />
<img class="overlay" src="inputDateOverlay.png" />
</div>
...
As it is shown in the listing above there are three HTML attributes - "title" , "name" , and "value" - are needed to be parameterize the generated markup.
You map the HTML attributes to the corresponding UIComponent attributes:
...
<div title="[title]">
<input name="[clientID]" value="[converted value]" />
<img class="overlay" src="inputDateOverlay.png" />
</div>
...
All information about styles applied to the <inputDate> component is considered in the following chapter.
This is the result of your prototype which shows a simple page with an input field and an icon indicating that this is a date field:
Component functionality typically centers around two actions: decoding and encoding data. Decoding is the process of converting incoming request parameters to the values of the component. Encoding is the process of converting the current values of the component into the corresponding markup. In the following figure you can see decoding and encoding occur in the JSF lifecycle:
Thus, JSF components consist of two parts: the component class and the renderer. The component class is responsible for the state and behavior of a UI component and will be discussed later in the "Configuring component" section.
The Renderer is responsible for the JSF component representation. It generates the
appropriate client-side markup, such as HTML, WML, XUL, etc. Renderer is also
responsible for the converting information coming from the client to the proper type
for the component (for example, a string value from the request is converted to a
strongly type Date object).
It is necessary to create following renderer classes for the <inputDate> component:
InputDateRendererclass where you should overrideencode()methods for encoding the markup and resourcesInputDateRendererBaseclass where you should overridedecode()method. You could also define associated converter in this class.
You could actually implement the renderer-specific component subclass that
exposes client-side attributes such as
"style"
,
"class"
, etc. It is common practice to implement the client-specific component
subclass to make some aspects of application development easier, but in our case we
do not need to do it. The
<inputDate>
is a simple UIInput component, therefore
InputDateRenderer class generates all the markup itself.
It is a time to start creating the InputDateRenderer class.
The smartest way to create the InputDateRenderer class is a Templating mechanism,
one of the most convenient features of the Component Development Kit (CDK).
The Component Development Kit (CDK) allows to use templates for generation Renderer class.
Templates are JSP-like markup pages with special tags that are converted into Renderer by a build script.
It's possible to use evaluated expressions in components templates with the help of scriptlets. It's also possible to create the base class for a template to implement additional functions in it, so as the functions could be called from the template. Hence, in the generated Renderer class there are corresponding function calls on the place of these elements.
Let's create the template for HTML 4.0 markup. At first you should proceed to the inputDate/src/main/templates/org/mycompany directory where htmlInputDate.jspx template file is stored. This file contains a Template Skeleton like this one:
<?xml version="1.0" encoding="UTF-8"?>
<f:root
xmlns:f="http://ajax4jsf.org/cdk/template"
xmlns:c=" http://java.sun.com/jsf/core"
xmlns:ui=" http://ajax4jsf.org/cdk/ui"
xmlns:u=" http://ajax4jsf.org/cdk/u"
xmlns:x=" http://ajax4jsf.org/cdk/x"
class="org.mycompany.renderkit.html.InputDateRenderer"
baseclass="org.ajax4jsf.renderkit.AjaxComponentRendererBase"
component="org.mycompany.component.UIInputDate"
>
<f:clientid var="clientId"/>
<div id="#{clientId}"
x:passThruWithExclusions="value,name,type,id"
>
</div>
</f:root>
According to the created UI prototype you need to extend Template Skeleton with proper elements:
<div>-wrapper element with "title", "value", "name", "type", "id" attributes and with the"caption" facet
...
<c:object var="caption" type="javax.faces.component.UIComponent"/>
<jsp:scriptlet>
caption = component.getFacet("caption");
if(caption !=null && caption.isRendered()) {
</jsp:scriptlet>
<div id="#{clientId}_caption" class="my-inputDate-caption #{component.attributes['captionClass']}">
<f:insertComponent value="#{caption}"/>
</div>
<jsp:scriptlet>
}
</jsp:scriptlet>
<div id="#{clientId}" title="#{value}" x:passThruWithExclusions="value,name,type,id">
...
</div>
...
<input> element with "id", "value", "name", "type", "class", "style" attributes. It is possible to use the "icon" facet in order to redefine a default icon of the component.
...
<input id="#{clientId}"
name="#{clientId}"
type="text"
value="#{this:getValueAsString(context, component)}"
class="my-inputDate-input #{component.attributes['inputClass']}"
style="#{component.attributes['inputStyle']}"/>
...
<img> element with "src", "class", "style" attributes which defines a default icon of the component. In order to add an image to the Template you should register it with the help of <f:resource> template tag and bind to a variable specified by the "var" attribute:
...
<f:resource name="/org/mycompany/renderkit/html/images/inputDate.png" var="icon" />
...
<img src="#{icon}" class="my-inputDate-icon #{component.attributes['iconClass']}" style="#{component.attributes['iconStyle']}"/>
...
The <inputDate> component uses styles and scripts that should be defined in the template with the help of <h:styles> and <h:scripts> tags:
...
<h:scripts>
new org.ajax4jsf.javascript.PrototypeScript(),
/org/mycompany/renderkit/html/scripts/inputDate.js
</h:scripts>
<h:styles>/org/mycompany/renderkit/html/css/inputDate.xcss</h:styles>
...
How to register all resources is explained in the "Component resources registration" chapter.
Important:
Don't forget to add namespace xmlns:h=" http://ajax4jsf.org/cdk/h" to the
<f:root> element:
<?xml version="1.0" encoding="UTF-8"?>
<f:root
...
xmlns:h=" http://ajax4jsf.org/cdk/h"
...
>
...
</f:root>
Here is a full example of the template for the <inputDate> component: htmlInputDate.jspx.
Note:
As is easy to see, in the Template Skeleton the Renderer Baseclass is org.ajax4jsf.renderkit.AjaxComponentRendererBase.
You need to define Renderer Base class special for the <inputDate> component.
In the next section "Creating a Renderer Base class"
we will create Renderer Base class org.mycompany.renderkit.InputDateRendererBase.
All the Template tags you could find in the "Template tags overview" chapter.
After the component tree is restored on the Restore View Phase ,
each component in the tree extracts its new value from the request parameters
by using its decode() method. Then the value is stored locally on the component.
So in the InputDateRendererBase class you need to override
the decode() method:
...
public void decode(FacesContext context, UIComponent component){
ExternalContext external = context.getExternalContext();
Map requestParams = external.getRequestParameterMap();
UIInputDate inputDate = (UIInputDate)component;
String clientId = inputDate.getClientId(context);
String submittedValue = (String)requestParams.get(clientId);
if (submittedValue != null) {
inputDate.setSubmittedValue(submittedValue);
}
}
...
As you see in the example above the decode() method reads values from request parameters,
grabs the clientId from the component to identify the request parameter to be looked up.
The clientId is calculated as the fully qualified name of the component given its container path:
nameOfForm:nameOfComponent (for example myForm:inputDate).
The last step of the decode() method is to store the submitted value locally on the component.
Note:
By default, the base Renderer implementation returns the submittedValue directly without any conversion!
If you want to convert submitted value to a strongly typed object you should implement Converter
and the getConvertedValue() method in your Renderer class (in our case in the InputDateRendererBase class).
As it was mentioned before the <inputDate> component at the Apply Request Values phase takes a value and pushes it to the model as a strongly typed Date object. Therefore you need to implement a Converter in the Renderer Base class and also check whether a Converter has been already attached by the application developer. If the conversion of the value fails, an error message associated with the component is generated and queued on FacesContext.
The getConverter() method of the InputDateRendererBase class returns the a converter, as shown in the following example:
...
private Converter getConverter(FacesContext context, UIInputDate inputDate){
Converter converter = inputDate.getConverter();
if (converter == null){
// default the converter
DateTimeConverter datetime = new DateTimeConverter();
datetime.setLocale(context.getViewRoot().getLocale());
datetime.setTimeZone(TimeZone.getDefault());
datetime.setType("date");
datetime.setDateStyle("medium");
datetime.setPattern("d/m/y");
converter = datetime;
}
return converter;
}
...
During the converter creation you should check whether the application developer has attached a Converter to the <inputDate> component already (for example, <f:convertDateTime>) . If not you should follow the next steps:
create a new DateTimeConverter
get the locale for the client from the context with the help of the
getLocale()method and set it on the new Converter by means of thesetLocale()methodset the time zone, date type, date style, and date pattern on the new converter with the help of
setTimeZone(),setType(),setDateStyle(), andsetPattern()methods respectivelyreturn the Converter
After the Apply Request Values phase the application enters the
Process Validation phase during which the validate() method
calls the getConvertedValue() method on every submitted value and passes
the newly submitted value from the decode process.
The getConvertedValue() method converts the submitted value to a strongly typed
object (in our case Date) using the getAsObject() method.
Then the new strongly typed object is validated and if there are no errors
Process Validation phase ends. Otherwise the getConvertedValue() method
throws a ConverterException.
Here is the snippet:
...
public Object getConvertedValue(FacesContext context, UIComponent component, Object submittedValue) throws ConverterException{
UIInputDate inputDate = (UIInputDate)component;
Converter converter = getConverter(context, inputDate);
String valueString = (String)submittedValue;
return converter.getAsObject(context, component, valueString);
}
...
Finally on the the Renderer Response phase the value of the component is rendered back to the view.
The converter is responsible for transforming the object data back in to a string representation, so you need to
implement getValueAsString() method:
Here is the example:
...
protected String getValueAsString(FacesContext context, UIComponent component) throws IOException {
UIInputDate inputDate = (UIInputDate) component;
String valueString = (String) inputDate.getSubmittedValue();
if (valueString == null) {
Object value = inputDate.getValue();
if (value != null) {
Converter converter = getConverter(context, inputDate);
valueString = converter.getAsString(context, component, value);
}
}
return valueString;
}
...
You could find the whole example of the InputDateRendererBase class here.
Registering component resources