// Copyright 2004, 2005 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package org.apache.tapestry.link;
import org.apache.hivemind.ApplicationRuntimeException;
import org.apache.hivemind.HiveMind;
import org.apache.tapestry.IMarkupWriter;
import org.apache.tapestry.IRequestCycle;
import org.apache.tapestry.Tapestry;
import org.apache.tapestry.components.ILinkComponent;
import org.apache.tapestry.engine.ILink;
/**
* Default implementation of {@link org.apache.tapestry.link.ILinkRenderer}, which does nothing
* special. Can be used as a base class to provide additional handling.
*
* @author Howard Lewis Ship, David Solis
* @since 3.0
*/
public class DefaultLinkRenderer implements ILinkRenderer
{
/**
* A shared instance used as a default for any link that doesn't explicitly override.
*/
public static final ILinkRenderer SHARED_INSTANCE = new DefaultLinkRenderer();
public void renderLink(IMarkupWriter writer, IRequestCycle cycle, ILinkComponent linkComponent)
{
IMarkupWriter wrappedWriter = null;
if (cycle.getAttribute(Tapestry.LINK_COMPONENT_ATTRIBUTE_NAME) != null)
throw new ApplicationRuntimeException(Tapestry
.getMessage("AbstractLinkComponent.no-nesting"), linkComponent, null, null);
cycle.setAttribute(Tapestry.LINK_COMPONENT_ATTRIBUTE_NAME, linkComponent);
boolean hasBody = getHasBody();
boolean disabled = linkComponent.isDisabled();
if (!disabled)
{
ILink l = linkComponent.getLink(cycle);
if (hasBody)
writer.begin(getElement());
else
writer.beginEmpty(getElement());
writer.attribute(getUrlAttribute(), constructURL(l, linkComponent.getAnchor(), cycle));
String target = linkComponent.getTarget();
if (HiveMind.isNonBlank(target))
writer.attribute(getTargetAttribute(), target);
beforeBodyRender(writer, cycle, linkComponent);
// Allow the wrapped components a chance to render.
// Along the way, they may interact with this component
// and cause the name variable to get set.
wrappedWriter = writer.getNestedWriter();
}
else
wrappedWriter = writer;
if (hasBody)
linkComponent.renderBody(wrappedWriter, cycle);
if (!disabled)
{
afterBodyRender(writer, cycle, linkComponent);
linkComponent.renderAdditionalAttributes(writer, cycle);
if (hasBody)
{
wrappedWriter.close();
// Close the <element> tag
writer.end();
}
else
writer.closeTag();
}
cycle.removeAttribute(Tapestry.LINK_COMPONENT_ATTRIBUTE_NAME);
}
/**
* Converts the EngineServiceLink into a URI or URL. This implementation simply invokes
* {@link ILink#getURL(String, boolean)}.
*/
protected String constructURL(ILink link, String anchor, IRequestCycle cycle)
{
return link.getURL(anchor, true);
}
/**
* Invoked after the href attribute has been written but before the body of the link is rendered
* (but only if the link is not disabled).
* <p>
* This implementation does nothing.
*/
protected void beforeBodyRender(IMarkupWriter writer, IRequestCycle cycle, ILinkComponent link)
{
}
/**
* Invoked after the body of the link is rendered, but before
* {@link ILinkComponent#renderAdditionalAttributes(IMarkupWriter, IRequestCycle)}is invoked
* (but only if the link is not disabled).
* <p>
* This implementation does nothing.
*/
protected void afterBodyRender(IMarkupWriter writer, IRequestCycle cycle, ILinkComponent link)
{
}
/** @since 3.0 * */
protected String getElement()
{
return "a";
}
protected String getUrlAttribute()
{
return "href";
}
protected String getTargetAttribute()
{
return "target";
}
protected boolean getHasBody()
{
return true;
}
}