JSF ajax hello world example

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Ajax:

AJAX refers to Asynchronous JavaScript and XML. It provides the following features:
1.Exchanging the data between web page and server with reloading the webpage.
2.Updating the parts of web page without refreshing or reloading the whole web page.

JSF use f:ajax tag to perform ajax operations.

Syntax:

<f:ajax execute="inputComponentId" render="outputComponentId" />

1.Execute: Execute attribute takes the ids of components whose value have to be sent to server for processing. In case of multiple ids, separate them by space.
2.Render: Render attribute takes the ids of those components which have to be updated after ajax request.

Example explanation:

Create a managed bean class “HelloWorld.java” which is used for interacting with User Interface and business logic. HelloWorld.java contains the getter method of message property. The @ManagedBean annotation property specify the managed bean name. The @SessionScoped annotation specify the scope of the managed bean. Insert the JSF controller servlet “FacesServlet” entry into web.xml. Create a jsf page “helloworld.xhtml”. Use f:ajax tag to perform ajax operations.

Example:

HelloWorld.java

package com.w3schools.business;
 
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
 
/**
 * Managed bean.
 * @author w3schools
 */
@ManagedBean(name="helloWorld")
@SessionScoped
public class HelloWorld {
	//Managed bean property
	private String userName;
 
	//Getter - setters 
	public String getUserName() {
		return userName;
	}
 
	public void setUserName(String userName) {
		this.userName = userName;
	}
 
	public String getHelloMessage() {
		if(userName == null || userName.equals("")){
			return "";
		}else{
			return "Hello " + userName;
		}
	}
}

faces-config.xml

<?xml version="1.0" encoding="windows-1252"?>
<faces-config version="2.0" 
xmlns="http://java.sun.com/xml/ns/javaee" 
xmlns:xi="http://www.w3.org/2001/XInclude" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
http://java.sun.com/xml/ns/javaee/web-facesconfig_2_0.xsd">
 
</faces-config>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" 
    	xmlns="http://java.sun.com/xml/ns/javaee" 
    	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
    	http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
 
    <servlet>
        <servlet-name>faces</servlet-name>
        <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
    </servlet>
 
    <servlet-mapping>
        <servlet-name>faces</servlet-name>
        <url-pattern>/faces/*</url-pattern>
    </servlet-mapping>
 
</web-app>

helloworld.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">
	<h:head>
		<title>JSF hello world example using ajax.</title>
	</h:head>
    <h:body>
    	<h2>JSF hello world example using ajax.</h2>
 
    	<h:form>
    	   <h:inputText id="name" value="#{helloWorld.userName}"/>
    	   <br/> <br/>
    	   <h:commandButton value="Say Hello">
    		 <f:ajax execute="name" render="sayHello" />
    	   </h:commandButton>
 
    	   <h2>
    	     <h:outputText id="sayHello" 
                           value="#{helloWorld.helloMessage}"/>
    	   </h2>	
    	</h:form>
 
    </h:body>
 
</html>

URL:

http://localhost:7001/JSFExample3/faces/helloworld.xhtml

Output:

JSF example3-1
 
Enter the name and click on Say Hello button.
 
JSF example3-2
 
Download this example.