SOME SIMPLE EXAMPLES FOR
BUILT-IN AJAX
==========================
Let us consider the following ajaxtime.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:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html">
<h:body>
<f:view>
<h:form>
<h:commandButton id='button1' value="show time" >
<f:ajax
</h:commandButton>
<h:outputText value="#{timedisplayer.time}" id="label1"/>
<br/>
<h:commandButton id='button2' value="greet" >
<f:ajax
</h:commandButton>
<h:outputText value="#{timedisplayer.greeting}" id="label2"/>
</h:form>
</f:view>
</h:body>
</html>
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Carefully note the <f:ajax
What this page means will become clear when we see the code for
// timedisplayer.java
package mypack;
import java.util.*;
import java.io.Serializable;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
@ManagedBean(name="timedisplayer")
@SessionScoped
public class timedisplayer
{
int n;
public Date getTime ()
{
return (new Date());
}
public String getGreeting()
{
String greeting;
n = n+1;
if(n%2==1) { greeting="hello";}
else { greeting="welcome!";}
return greeting;
}
}
===============================
Let us now explain.
When button1 is clicked, ajax
the backing bean named 'timedisplayer'.
'render' means that label1 is to be updated by the
result of ajax
Where is the 'time' attribute? Not necessary.
When we provide getXXX , it automatically means that.
--
Coming to button2, ajax
and label2 is bound to greeting property.
The syntax is a bit confusing but the result is fine!
=====================================
Anyway, 'clicking' buttons , is NOT the ideal demo for ajax
So, I will try to develop a demo which uses 'mouseover'.or similar action.
