- JSF Tutorial
- JSF - Home
- JSF - Overview
- JSF - Environment Setup
- JSF - Architecture
- JSF - Life Cycle
- JSF - First Application
- JSF - Managed Beans
- JSF - Page Navigation
- JSF - Basic Tags
- JSF - Facelet Tags
- JSF - Convertor Tags
- JSF - Validator Tags
- JSF - DataTable
- JSF - Composite Components
- JSF - Ajax
- JSF - Event Handling
- JSF - JDBC Integration
- JSF - Spring Integration
- JSF - Expression Language
- JSF - Internationalization
- JSF Useful Resources
- JSF - Quick Guide
- JSF - Useful Resources
- JSF - Discussion
JSF - Application Events
JSF provides system event listeners to perform application specific tasks during JSF application Life Cycle.
S.No | System Event & Description |
---|---|
1 | PostConstructApplicationEvent Fires when the application starts. Can be used to perform initialization tasks after the application has started. |
2 | PreDestroyApplicationEvent Fires when the application is about to shut down. Can be used to perform cleanup tasks before the application is about to shut down. |
3 | PreRenderViewEvent Fires before a JSF page is to be displayed. Can be used to authenticate the user and provide restricted access to JSF View. |
System Events can be handled in the following manner.
S.No | Technique & Description |
---|---|
1 | SystemEventListener Implement SystemEventListener interface and register the system-event-listener class in faces-config.xml |
2 | Method Binding Pass the name of the managed bean method in listener attribute of f:event. |
SystemEventListener
Implement SystemEventListener Interface.
public class CustomSystemEventListener implements SystemEventListener { @Override public void processEvent(SystemEvent event) throws AbortProcessingException { if(event instanceof PostConstructApplicationEvent) { System.out.println("Application Started. PostConstructApplicationEvent occurred!"); } } }
Register custom system event listener for system event in faces-config.xml.
<system-event-listener> <system-event-listener-class> com.tutorialspoint.test.CustomSystemEventListener </system-event-listener-class> <system-event-class> javax.faces.event.PostConstructApplicationEvent </system-event-class> </system-event-listener>
Method Binding
Define a method
public void handleEvent(ComponentSystemEvent event) { data = "Hello World"; }
Use the above method.
<f:event listener = "#{user.handleEvent}" type = "preRenderView" />
Example Application
Let us create a test JSF application to test the system events 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 | Modify UserData.java file as explained below. |
3 | Create CustomSystemEventListener.java file under a package com.tutorialspoint.test. Modify it as explained below |
4 | Modify home.xhtml as explained below. |
5 | Create faces-config.xml in WEB-INF folder.Modify it as explained below. Keep the rest of the files unchanged. |
6 | Compile and run the application to make sure the business logic is working as per the requirements. |
7 | Finally, build the application in the form of war file and deploy it in Apache Tomcat Webserver. |
8 | Launch your web application using appropriate URL as explained below in the last step. |
UserData.java
package com.tutorialspoint.test; import java.io.Serializable; import javax.faces.bean.ManagedBean; import javax.faces.bean.SessionScoped; import javax.faces.event.ComponentSystemEvent; @ManagedBean(name = "userData", eager = true) @SessionScoped public class UserData implements Serializable { private static final long serialVersionUID = 1L; private String data = "sample data"; public void handleEvent(ComponentSystemEvent event) { data = "Hello World"; } public String getData() { return data; } public void setData(String data) { this.data = data; } }
CustomSystemEventListener.java
package com.tutorialspoint.test; import javax.faces.application.Application; import javax.faces.event.AbortProcessingException; import javax.faces.event.PostConstructApplicationEvent; import javax.faces.event.PreDestroyApplicationEvent; import javax.faces.event.SystemEvent; import javax.faces.event.SystemEventListener; public class CustomSystemEventListener implements SystemEventListener { @Override public boolean isListenerForSource(Object value) { //only for Application return (value instanceof Application); } @Override public void processEvent(SystemEvent event) throws AbortProcessingException { if(event instanceof PostConstructApplicationEvent) { System.out.println("Application Started. PostConstructApplicationEvent occurred!"); } if(event instanceof PreDestroyApplicationEvent) { System.out.println("PreDestroyApplicationEvent occurred. Application is stopping."); } } }
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"> <h:head> <title>JSF tutorial</title> </h:head> <h:body> <h2>Application Events Examples</h2> <f:event listener = "#{userData.handleEvent}" type = "preRenderView" /> #{userData.data} </h:body> </html>
faces-config.xhtml
<?xml version = "1.0" encoding = "UTF-8"?> <faces-config 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-facesconfig_2_0.xsd" version = "2.0"> <application> <!-- Application Startup --> <system-event-listener> <system-event-listener-class> com.tutorialspoint.test.CustomSystemEventListener </system-event-listener-class> <system-event-class> javax.faces.event.PostConstructApplicationEvent </system-event-class> </system-event-listener> <!-- Before Application is to shut down --> <system-event-listener> <system-event-listener-class> com.tutorialspoint.test.CustomSystemEventListener </system-event-listener-class> <system-event-class> javax.faces.event.PreDestroyApplicationEvent </system-event-class> </system-event-listener> </application> </faces-config>
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.
Look into your web-server console output. You will see the following result.
INFO: Deploying web application archive helloworld.war Dec 6, 2012 8:21:44 AM com.sun.faces.config.ConfigureListener contextInitialized INFO: Initializing Mojarra 2.1.7 (SNAPSHOT 20120206) for context '/helloworld' Application Started. PostConstructApplicationEvent occurred! Dec 6, 2012 8:21:46 AM com.sun.faces.config.ConfigureListener $WebConfigResourceMonitor$Monitor <init> INFO: Monitoring jndi:/localhost/helloworld/WEB-INF/faces-config.xml for modifications Dec 6, 2012 8:21:46 AM org.apache.coyote.http11.Http11Protocol start INFO: Starting Coyote HTTP/1.1 on http-8080 Dec 6, 2012 8:21:46 AM org.apache.jk.common.ChannelSocket init INFO: JK: ajp13 listening on /0.0.0.0:8009 Dec 6, 2012 8:21:46 AM org.apache.jk.server.JkMain start INFO: Jk running ID = 0 time = 0/24 config = null Dec 6, 2012 8:21:46 AM org.apache.catalina.startup.Catalina start INFO: Server startup in 44272 ms