/*
* $Id: UIComponentELTag.java,v 1.7 2007/01/29 07:29:00 rlubke Exp $
*/
/*
* The contents of this file are subject to the terms
* of the Common Development and Distribution License
* (the License). You may not use this file except in
* compliance with the License.
*
* You can obtain a copy of the License at
* https://javaserverfaces.dev.java.net/CDDL.html or
* legal/CDDLv1.0.txt.
* See the License for the specific language governing
* permission and limitations under the License.
*
* When distributing Covered Code, include this CDDL
* Header Notice in each file and include the License file
* at legal/CDDLv1.0.txt.
* If applicable, add the following below the CDDL Header,
* with the fields enclosed by brackets [] replaced by
* your own identifying information:
* "Portions Copyrighted [year] [name of copyright owner]"
*
* [Name of File] [ver.__] [Date]
*
* Copyright 2005 Sun Microsystems Inc. All Rights Reserved
*/
package javax.faces.webapp;
import javax.el.ELException;
import javax.el.ELContext;
import javax.el.ValueExpression;
import javax.faces.FacesException;
import javax.faces.application.Application;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.Tag;
/**
* <p>{@link UIComponentELTag} specializes its superclass to allow for
* properties that take their values from EL API expressions.</p>
*
* <p>This tag is designed for use with Faces version 1.2 and JSP
* version 2.1 containers.</p>
*
*/
public abstract class UIComponentELTag extends UIComponentClassicTagBase implements Tag {
// ------------------------------------------------------------- Attributes
/**
* <p>The value binding expression (if any) used to wire up this component
* to a {@link UIComponent} property of a JavaBean class.</p>
*/
private ValueExpression binding = null;
/**
* <p>Set the value expression for our component.</p>
*
* @param binding The new value expression
*
* @throws JspException if an error occurs
*/
public void setBinding(ValueExpression binding) throws JspException {
this.binding = binding;
}
protected boolean hasBinding() {
return null != binding;
}
/**
* <p>An override for the rendered attribute associated with our
* {@link UIComponent}.</p>
*/
private ValueExpression rendered = null;
/**
* <p>Set an override for the rendered attribute.</p>
*
* @param rendered The new value for rendered attribute
*/
public void setRendered(ValueExpression rendered) {
this.rendered = rendered;
}
/**
* <p>Return the {@link ELContext} for the {@link FacesContext} for
* this request.</p>
*
* <p>This is a convenience for
* <code>getFacesContext().getELContext()</code>.</p>
*/
protected ELContext getELContext() {
FacesContext fc = getFacesContext();
ELContext result = null;
if (null != fc) {
result = fc.getELContext();
}
return result;
}
// ------------------------------------------------------------ Tag Methods
/**
* <p>Release any resources allocated during the execution of this
* tag handler.</p>
*/
public void release() {
this.binding = null;
this.rendered = null;
super.release();
}
// ------------------------------------------------------- Protected Methods
/**
* <p>Override properties and attributes of the specified component,
* if the corresponding properties of this tag handler instance were
* explicitly set. This method must be called <strong>ONLY</strong>
* if the specified {@link UIComponent} was in fact created during
* the execution of this tag handler instance, and this call will occur
* <strong>BEFORE</strong> the {@link UIComponent} is added to
* the view.</p>
*
* <p>Tag subclasses that want to support additional set properties
* must ensure that the base class <code>setProperties()</code>
* method is still called. A typical implementation that supports
* extra properties <code>foo</code> and <code>bar</code> would look
* something like this:</p>
* <pre>
* protected void setProperties(UIComponent component) {
* super.setProperties(component);
* if (foo != null) {
* component.setAttribute("foo", foo);
* }
* if (bar != null) {
* component.setAttribute("bar", bar);
* }
* }
* </pre>
*
* <p>The default implementation overrides the following properties:</p>
* <ul>
* <li><code>rendered</code> - Set if a value for the
* <code>rendered</code> property is specified for
* this tag handler instance.</li>
* <li><code>rendererType</code> - Set if the <code>getRendererType()</code>
* method returns a non-null value.</li>
* </ul>
*
* @param component {@link UIComponent} whose properties are to be
* overridden
*/
protected void setProperties(UIComponent component) {
// The "id" property is explicitly set when components are created
// so it does not need to be set here
if (rendered != null) {
if (rendered.isLiteralText()) {
try {
component.setRendered(Boolean.valueOf(rendered.getExpressionString())
.booleanValue());
} catch (ELException e) {
throw new FacesException(e);
}
} else {
component.setValueExpression("rendered", rendered);
}
}
if (getRendererType() != null) {
component.setRendererType(getRendererType());
}
}
/**
* <p>Create and return a new child component of the type returned by
* calling <code>getComponentType()</code>. If this {@link UIComponentELTag}
* has a non-null <code>binding</code> attribute, this is done by
* call {@link Application#createComponent} with the {@link ValueExpression}
* created for the <code>binding</code> attribute, and the
* {@link ValueExpression} will be stored on the component. Otherwise,
* {@link Application#createComponent} is called with only
* the component type. Finally, initialize the components id
* and other properties.
* </p>
* @param context {@link FacesContext} for the current request
* @param newId id of the component
*/
protected UIComponent createComponent(FacesContext context, String newId) throws JspException {
UIComponent component;
Application application = context.getApplication();
if (binding != null) {
component = application.createComponent(binding, context,
getComponentType());
component.setValueExpression("binding", binding);
} else {
component = application.createComponent(getComponentType());
}
component.setId(newId);
setProperties(component);
return component;
}
}