JSF - Composite Components

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JSF provides the developers with a powerful capability to define their own custom components, which can be used to render custom contents.

Define Custom Component

Defining a custom component in JSF is a two-step process.

Step Description
1a

Create a resources folder.

Create a xhtml file in resources folder with a composite namespace.
1b

Use composite tags composite:interface, composite:attribute and composite:implementation, to define content of the composite component. Use cc.attrs in composite:implementation to get variable defined using composite:attribute in composite:interface.

Step 1a: Create Custom Component : loginComponent.xhtml

Create a folder howcodex in resources folder and create a file loginComponent.xhtml in it.

Use composite namespace in html header.

<html xmlns = "http://www.w3.org/1999/xhtml"   
   xmlns:h = "http://java.sun.com/jsf/html"
   xmlns:f = "http://java.sun.com/jsf/core"
   xmlns:composite = "http://java.sun.com/jsf/composite">
...
</html>

Step 1b: Use Composite Tags : loginComponent.xhtml

Following table describes the use of composite tags.

S.No Tag & Description
1

composite:interface

Declares configurable values to be used in composite:implementation.
2

composite:attribute

Configuration values are declared using this tag.
3

composite:implementation

Declares JSF component. Can access the configurable values defined in composite:interface using #{cc.attrs.attribute-name} expression.

 
<composite:interface>
   <composite:attribute name = "usernameLabel" />
   <composite:attribute name = "usernameValue" />
</composite:interface>

<composite:implementation>
<h:form>
   #{cc.attrs.usernameLabel} : 
   <h:inputText id = "username" value = "#{cc.attrs.usernameValue}" />
</h:form>

Use Custom Component

Using a custom component in JSF is a simple process.

Step Description
2a Create a xhtml file and use custom component's namespace. Namespace will the http://java.sun.com/jsf/<folder-name> where folder-name is folder in resources directory containing the custom component
2b Use the custom component as normal JSF tags

Step 2a: Use Custom Namespace: home.xhtml

<html xmlns = "http://www.w3.org/1999/xhtml"   
   xmlns:h = "http://java.sun.com/jsf/html"
   xmlns:ui = "http://java.sun.com/jsf/facelets">
   xmlns:tp = "http://java.sun.com/jsf/composite/howcodex">

Step 2b: Use Custom Tag: home.xhtml and Pass Values

<h:form>
   <tp:loginComponent 
      usernameLabel = "Enter User Name: " 
      usernameValue = "#{userData.name}" />
</h:form>

Example Application

Let us create a test JSF application to test the custom component in JSF.

Step Description
1 Create a project with a name helloworld under a package com.howcodex.test as explained in the JSF - First Application chapter.
2 Create resources folder under src → main folder.
3 Create howcodex folder under src → main → resources folder.
4 Create loginComponent.xhtml file under src → main → resources → howcodex folder.
5 Modify UserData.java file as explained below.
6 Modify home.xhtml as explained below. Keep the rest of the files unchanged.
7 Compile and run the application to make sure the business logic is working as per the requirements.
8 Finally, build the application in the form of war file and deploy it in Apache Tomcat Webserver.
9 Launch your web application using appropriate URL as explained below in the last step.

loginComponent.xhtml

<?xml version = "1.0" encoding = "UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns = "http://www.w3.org/1999/xhtml"   
   xmlns:h = "http://java.sun.com/jsf/html"
   xmlns:f = "http://java.sun.com/jsf/core"
   xmlns:composite = "http://java.sun.com/jsf/composite">
   
   <composite:interface>
      <composite:attribute name = "usernameLabel" />
      <composite:attribute name = "usernameValue" />
      <composite:attribute name = "passwordLabel" />
      <composite:attribute name = "passwordValue" />
      <composite:attribute name = "loginButtonLabel" />
      <composite:attribute name = "loginButtonAction" 
         method-signature = "java.lang.String login()" />
   </composite:interface>
   
   <composite:implementation>
      <h:form>
         <h:message for = "loginPanel" style = "color:red;" />
         
         <h:panelGrid columns = "2" id = "loginPanel">
            #{cc.attrs.usernameLabel} : 
            <h:inputText id = "username" value = "#{cc.attrs.usernameValue}" />
            #{cc.attrs.passwordLabel} : 
            <h:inputSecret id = "password" value = "#{cc.attrs.passwordValue}" />
         </h:panelGrid>
         
         <h:commandButton action = "#{cc.attrs.loginButtonAction}" 
            value = "#{cc.attrs.loginButtonLabel}"/>
      </h:form>
   </composite:implementation>
</html>

UserData.java

package com.howcodex.test;

import java.io.Serializable;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;

@ManagedBean(name = "userData", eager = true)
@SessionScoped
public class UserData implements Serializable {
   private static final long serialVersionUID = 1L;
   private String name;
   private String password;
   
   public String getName() {
      return name;
   }
   
   public void setName(String name) {
      this.name = name;
   }
   
   public String getPassword() {
      return password;
   }
   
   public void setPassword(String password) {
      this.password = password;
   }	
   
   public String login() {
      return "result";
   }	
}

home.xhtml

<?xml version = "1.0" encoding = "UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns = "http://www.w3.org/1999/xhtml"   
   xmlns:h = "http://java.sun.com/jsf/html"
   xmlns:f = "http://java.sun.com/jsf/core"
   xmlns:tp = "http://java.sun.com/jsf/composite/howcodex">
   
   <h:head>
      <title>JSF tutorial</title>		     
   </h:head>
   
   <h:body> 
      <h2>Custom Component Example</h2>
      
      <h:form>
      <tp:loginComponent 
         usernameLabel = "Enter User Name: " 
         usernameValue = "#{userData.name}" 
         passwordLabel = "Enter Password: " 
         passwordValue = "#{userData.password}"
         loginButtonLabel = "Login" 
         loginButtonAction = "#{userData.login}" />
      </h:form>
   </h:body>
</html>

Once you are ready with all the changes done, let us compile and run the application as we did in JSF - First Application chapter. If everything is fine with your application, this will produce the following result.

JSF custom component
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