Already you’ve seen the implementation of monitoring Ajax (request/response) using monitor JavaScript function. That method is fragile, however, because it can be overwritten by another JavaScript method of the same name. To prevent that replacement from happening, you could name your function something more unique, such as net.javabeat.monitor.
For protecting our JavaScript from being overwritten, we implement a simple map that serves as namespace. it seems we’ve two newly concepts must be defined. When you implement a custom components that maintain data on the client. Putting that data in a map, keyed by the client identifier of the component to which the data is associated, is a way to ensure that multiple Ajax-based custom components of the same type that store data on the client, can exist in a single page.
1. The View
index.html
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core">
<h:head>
<script>
if(!net) var net = {}
if(!net.javabeat){
net.javabeat = {
monitor:
function (data){
var loading = document.getElementById("image");
if(data.status == "begin"){
loading.style.display = "block";
}
else if(data.status == "success"){
loading.style.display = "none";
}
}
}
}
</script>
<h:outputScript library="javax.faces" name="jsf.js"/>
</h:head>
<h:body>
<f:view>
<h1>JavaBeat JSF 2.2 Examples</h1>
<h2>JSF2 Using JavaScript Namespace Example</h2>
<h:form prependId="false">
<h:inputText id="input" value="#{indexBean.message}"/>
#{' '}
<h:commandButton value="Display Text" action="#{indexBean.action}">
<f:ajax execute="@this input" render="output" onevent="net.javabeat.monitor"></f:ajax>
</h:commandButton>
#{' '}
<h:outputText id="output" value="#{indexBean.message}"></h:outputText>
<h:graphicImage id="image" value="#{resource['images:ajax-loader.gif']}" style="display:none;"></h:graphicImage>
</h:form>
</f:view>
</h:body>
</html>
2. Managed Bean
package net.javabeat.jsf;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
@ManagedBean
@SessionScoped
public class IndexBean {
private String message;
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
public String action() throws Exception{
// Do heavy processing, simply :)
Thread.sleep(6000);
System.out.println(message);
return "";
}
}
3. The Deployment Descriptor (web.xml)
web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5" metadata-complete="true"> <context-param> <description>State saving method: 'client' or 'server' (=default). See JSF Specification 2.5.2 </description> <param-name>javax.faces.STATE_SAVING_METHOD</param-name> <param-value>client</param-value> </context-param> <context-param> <param-name>javax.faces.application.CONFIG_FILES</param-name> <param-value>/WEB-INF/faces-config.xml</param-value> </context-param> <servlet> <servlet-name>Faces Servlet</servlet-name> <servlet-class>javax.faces.webapp.FacesServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>Faces Servlet</servlet-name> <url-pattern>/faces/*</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>Faces Servlet</servlet-name> <url-pattern>*.xhtml</url-pattern> </servlet-mapping> <listener> <listener-class>com.sun.faces.config.ConfigureListener</listener-class> </listener> </web-app>
4. JSF2 JavaScript Namespace Demo
The below snapshots show you how can you employ the concept of JavaScript Namespace for preventing conflict naming of JavaScript function by providing a keyed map.
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