Wednesday, June 22, 2011
Tuesday, April 18, 2006
Setting focus on input fields with JSF and Facelets
JavaServer(tm) Faces components have a dynamic id. This can create problems when trying to access these components from JavaScript code on the client. I my case I wanted to do a very simple and common thing, set input focus on a specific field. One solution is to use a custom component called IDProxy (http://www.jsftutorials.net/proxyTag.html). This component makes it easy to obtain the dynamic generated id for it's parent element. While I found lots of articles on Internet explaining the use of IDProxy with JSF, I found no article that used Facelets as the rendering technique. Facelets (https://facelets.dev.java.net/) is a powerful templating system that allows you to define JSF views using HTML-style templates. In this article I will explain how I used IDProxy to set focus on an input field rendered with Facelets.
Download j4j.jar and put it in the WEB-INF/lib folder of your web project. Create a file called j4j.taglib.xml in the META-INF folder of your web project. The file should look like this:
<?xml version="1.0"?>
<!DOCTYPE facelet-taglib PUBLIC
"-//Sun Microsystems, Inc.//DTD Facelet Taglib 1.0//EN"
"http://java.sun.com/dtd/facelet-taglib_1_0.dtd">
<facelet-taglib>
<namespace>http://javascript4jsf.dev.java.net/</namespace>
<tag>
<tag-name>idProxy</tag-name>
<component>
<component-type>org.j4j.idProxy</component-type>
</component>
</tag>
</facelet-taglib>
Add the j4j namespace to the xhtml page where you want to use idProxy.
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html" xmlns:j4j="http://javascript4jsf.dev.java.net/">
Add an idProxy tag inside the input element that you want to get the dynamic id from. In my case I want to get the dynamic id of a field called username in a login dialog.
<h:outputlabel for="username">Username</h:outputLabel>
<h:inputtext id="username" value="#{user.username}">
<j4j:idproxy id="_focus"/>
</h:inputText>
Now you can extract the dynamic id through the idProxy element from JavaScript code. The title property of the idProxy element contain the generated id of it's parent element, that's the value we want.
<script language="javascript">
//<![CDATA[
var iid=document.getElementById("_focus");
if(iid != null) {
document.getElementById(iid.title).focus();
}
//]]>
</script>
If you put the JavaScript code in your facelets template, you just have to include the j4j namespace declaration and the idProxy tag in each page where you want to set focus on a field.
This works great for me, but I'm still puzzled... Why is such a common thing like setting focus not standardized in JSF?
Friday, January 20, 2006
Using Quartz job scheduler with Spring
Quartz is an open source job scheduling system that can be integrated with, or used along side virtually any J2EE or J2SE application. Quartz can be used to trigger jobs at a specific date and time, at regular intervals, or other very complex schedules.
Although Quartz can be used in a standalone system, this article focuses on using Quartz in a J2EE application built with the Spring framework. The Spring framework has built-in support for Quartz. All you have to do is put the Quartz runtime (quartz-1.x.x.jar) in your classpath, implement the business logic to be triggered, and put some entries in your Spring configuration file.
First you have to configure a scheduler with a list of triggers.
<bean id="scheduler"
class="org.springframework.scheduling.quartz.SchedulerFactoryBean">
<property name="triggers">
<list>
<ref local="reportTrigger"/>
</list>
</property>
</bean>
Then you configure the managed beans that you want to trigger. In this case, my business logic is implemented as a stateless session bean.
<bean id="mondayMorningReport" class="org.springframework.ejb.access.LocalStatelessSessionProxyFactoryBean"> <property name="jndiName"><value>ejb/mondayMorningReport</value></property> <property name="resourceRef"><value>true</value></property> <property name="businessInterface"> <value>com.mycompany.Report</value></property> </bean>
Finally you configure the trigger to fires at a specific time. In my case I want a report to execute every Monday morning at 6.30 am. I use the CronTriggerBean for this purpose.
<bean id="reportTrigger"
class="org.springframework.scheduling.quartz.CronTriggerBean">
<property name="jobDetail">
<bean
class="org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean">
<property name="targetObject"><ref bean="mondayMorningReport"/></property>
<property name="targetMethod"><value>printReport</value></property>
</bean>
</property>
<property name="cronExpression"><value>0 30 6 * * MON</value></property>
</bean>
A "Cron-Expression" is a string comprised of 6 or 7 fields separated by white space. The 6 mandatory and 1 optional fields are as follows:
| Field Name | Allowed Values | Allowed Special Characters |
|---|---|---|
| Seconds | 0-59 | , - * / |
| Minutes | 0-59 | , - * / |
| Hours | 0-23 | , - * / |
| Day-of-month | 1-31 | , - * ? / L W C |
| Month | 1-12 or JAN-DEC | , - * / |
| Day-of-Week | 1-7 or SUN-SAT | , - * ? / L C # |
| Year (Optional) | empty, 1970-2099 | , - * / |
The Quartz plumbing code is included in Spring 1.0 and above but you must also download the Quarts distribution and include its jar in your application. As of this writing, I use quartz-1.5.1.jar in my application.
Resources
- Quartz Job Scheduler: www.opensymphony.com/quartz/
- Spring Framework: www.springframework.org/
Wednesday, October 05, 2005
EJB3: @OneToMany and @OrderBy - Set versus List
Introduction
