Extend JSF Command Link

I found myself adding a Remove link throughout my JSF application. It looked like this:

<h:commandlink value="Remove" actionlistener="#{MyBean.remove}">


I wanted to add a confirm dialog. So I added this.

<h:commandlink value="Remove" actionlistener="#{MyBean.remove}" onclick="javascript return confirm('Are you sure')">


But as I copied and pasted this through 5 or 6 different pages, I got to thinking, there has to be a better way.

So I created a custom jsf component by extending Command Link.

Step 1

First step was to create my new tag. It simply wraps the default command link.

package com.acme;

import com.sun.faces.taglib.html_basic.CommandLinkTag;
import javax.el.MethodExpression;
import javax.el.ValueExpression;
import javax.faces.component.UIComponent;
import javax.faces.component.html.HtmlCommandLink;
import javax.faces.event.MethodExpressionActionListener;
import javax.faces.webapp.UIComponentELTag;

/**
* @author cmcintosh
*/
public class RemoveCommandLinkTag extends UIComponentELTag { // Declare a bean property for the hellomsg attribute.

CommandLinkTag commandLink = new CommandLinkTag();
ValueExpression value;
MethodExpression actionListener;

// Associate the renderer and component type.
public String getComponentType() {
return commandLink.getComponentType();
}

public String getRendererType() {
return commandLink.getRendererType();
}

@Override
protected void setProperties(UIComponent component) {
super.setProperties(component);
component.setValueExpression("value", value);
((HtmlCommandLink)component).addActionListener(new MethodExpressionActionListener(actionListener));
((HtmlCommandLink)component).setOnclick("javascript:return confirm('Are you sure you want to remove?')");

}
@Override
public void release() {
super.release();
commandLink.release();

}

public void setValue(ValueExpression value) {
this.value = value;

}
public void setActionListener(MethodExpression actionListener) {
this.actionListener = actionListener;
}
}

Step 2
Next I needed to create a tld.


<taglib version="2.0" xmlns="http://java.sun.com/xml/ns/j2ee" xsi="http://www.w3.org/2001/XMLSchema-instance" schemalocation="http://java.sun.com/xml/ns/j2ee web-jsptaglibrary_2_0.xsd">
<tlib-version>1.0</tlib-version>
<short-name>datastore</short-name>
<uri>/WEB-INF/tlds/datastore</uri>
<tag>
<name>RemoveCommandLink</name>
<tag-class>com.acme.datastore.web.components.tags.RemoveCommandLinkTag</tag-class>
<attribute>
<name>value</name>
<deferred-value>
<type>java.lang.String</type>
</deferred-value>
</attribute>
<attribute>
<name>actionListener</name>
<required>false</required>
<deferred-method>
<method-signature>
actionListener(javax.faces.event.ActionEvent)
</method-signature>
</deferred-method>
<type>String</type>
</attribute>

</tag>
</taglib>


This was one of the hardest parts note the deferred-method and deferredvalue. I've never encountered those before.

Step 3

Add it to the web.xml:
<jsp-config>
<taglib>
<taglib-uri>http://datastore.acme.com/datastore</taglib-uri>
<taglib-location>/WEB-INF/tlds/datastore.tld</taglib-location>
</taglib>
</jsp-config>

Step 4
Finally to use it:
<%@taglib prefix="ds" uri="http://datastore.acme.com/datastore"%>
.
.
.
<ds:removecommandlink value="Remove" actionlistener="#{ViewModifyTable.removeColumn}">
<f:param name="applicationId" value="#{ViewModifyTable.applicationId}">
<f:param name="tableName" value="#{ViewModifyTable.tableName}">
</f:param></f:param></ds:removecommandlink></h:commandlink></h:commandlink>

Configure logging level

Here is how I disabled hibernate JPA logging level in code.

Logger.getLogger("org.hibernate").setLevel(Level.SEVERE);

Readling List

XtraDb:

http://www.mysqlperformanceblog.com/2009/08/13/xtradb-the-top-10-enhancements/


Mysql performance blog

http://www.amazon.com/gp/product/0596101716?ie=UTF8&tag=perinc-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=0596101716

Pro JSF and Ajax by Jonas Jacobi and John R. Fallows

Read On: 8/17/09
Rating: 7 /10

Pros:

• I liked this summary of other applications and which component of MVC they target: Examples of frameworks are Struts (an open source controller framework);
  TopLink and Hibernate (model frameworks); and Tiles, Tapestry, XUL, and ADF UIX (so-
  called view frameworks).

Cons:

• Can be hard to read
  

Questions:

• Why do so many frameworks model navigation these days?
  

Comparing Web Frameworks: Struts, Spring MVC, Webwork, Tapestry & JSF

Read on: 08/17/2009
Rating: 2/10

Way outdated, by the time I got my hands on it. No fault of the authors it was made in 2005.

Pros:

• Concise

Cons:

• Its just a bunch of slides
  

Beginning Spring 2 by Dave Minter

Read On: 8/17/09
Rating: 8/10

Pros:

• Very good introduction to Spring
• Clear explanation of IoC and dependency injection
• Made a strong case for using Spring for all applications

Cons

• Would of liked more Spring annotation examples.
  
• The database example could of been expanded. In particular I wasn't sure what the purpose of the DAO's were.
  
• I would of liked a more detail on Spring MVC