Java Technology: 14. JSF - Composite Components

JSF provides developer a powerful capability to define 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 No.	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 tutorialspoint 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 use of composite tags.

S.N.	tag & Description
1	composite:interface Declare 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 No.	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 compoent
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/tutorialspoint">

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.tutorialspoint.test as explained in the JSF - First Application chapter.
2	Create resources folder under src > main folder.
3	Create tutorialspoint folder under src > main > resources folder.
4	Create loginComponent.xhtml file under src > main > resources > tutorialspoint folder.
5	Modify UserData.java file as explained below.
6	Modify home.xhtml as explained below. Keep rest of the files unchanged.
7	Compile and run the application to make sure 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.tutorialspoint.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/tutorialspoint">
   <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 following result:
JSF custom component

Java Technology

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Thứ Ba, 19 tháng 3, 2013

14. JSF - Composite Components