org.apache.felix.webconsole.SimpleWebConsolePlugin Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.felix.webconsole;
import java.net.URL;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Map;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceRegistration;
import org.osgi.util.tracker.ServiceTracker;
/**
* SimpleWebConsolePlugin is an utility class that provides default
* implementation of the {@link AbstractWebConsolePlugin} and supports the
* following features:
*
* - Methods for (un)registering the web console plugin service
* - Default implementation for resource loading
*
*/
public abstract class SimpleWebConsolePlugin extends AbstractWebConsolePlugin
{
// Serializable UID
private static final long serialVersionUID = 1500463493078823878L;
// used for standard AbstractWebConsolePlugin implementation
private final String label;
private final String title;
private final String category;
private final String css[];
private final String labelRes;
private final int labelResLen;
// used for service registration
private final Object regLock = new Object();
private ServiceRegistration reg;
// used to obtain services. Structure is: service name -> ServiceTracker
private final Map services = new HashMap();
/**
* Creates new Simple Web Console Plugin with the default category
* ({@code null})
*
* @param label the front label. See
* {@link AbstractWebConsolePlugin#getLabel()}
* @param title the plugin title . See
* {@link AbstractWebConsolePlugin#getTitle()}
* @param css the additional plugin CSS. See
* {@link AbstractWebConsolePlugin#getCssReferences()}
*/
public SimpleWebConsolePlugin( String label, String title, String css[] )
{
this( label, title, null, css );
}
/**
* Creates new Simple Web Console Plugin with the given category.
*
* @param label the front label. See
* {@link AbstractWebConsolePlugin#getLabel()}
* @param title the plugin title . See
* {@link AbstractWebConsolePlugin#getTitle()}
* @param category the plugin's navigation category. See
* {@link AbstractWebConsolePlugin#getCategory()}
* @param css the additional plugin CSS. See
* {@link AbstractWebConsolePlugin#getCssReferences()}
*/
public SimpleWebConsolePlugin( String label, String title, String category, String css[] )
{
if ( label == null )
{
throw new NullPointerException( "Null label" );
}
if ( title == null )
{
throw new NullPointerException( "Null title" );
}
this.label = label;
this.title = title;
this.category = category;
this.css = css;
this.labelRes = '/' + label + '/';
this.labelResLen = labelRes.length() - 1;
}
/**
* @see org.apache.felix.webconsole.AbstractWebConsolePlugin#getLabel()
*/
public final String getLabel()
{
return label;
}
/**
* @see org.apache.felix.webconsole.AbstractWebConsolePlugin#getTitle()
*/
public final String getTitle()
{
return title;
}
/**
* @see org.apache.felix.webconsole.AbstractWebConsolePlugin#getCategory()
*/
public String getCategory()
{
return category;
}
/**
* @see org.apache.felix.webconsole.AbstractWebConsolePlugin#getCssReferences()
*/
protected final String[] getCssReferences()
{
return css;
}
/**
* Called internally by {@link AbstractWebConsolePlugin} to load resources.
*
* This particular implementation depends on the label. As example, if the
* plugin is accessed as /system/console/abc, and the plugin
* resources are accessed like /system/console/abc/res/logo.gif,
* the code here will try load resource /res/logo.gif from the
* bundle, providing the plugin.
*
*
* @param path the path to read.
* @return the URL of the resource or null if not found.
*/
protected URL getResource( String path )
{
return ( path != null && path.startsWith( labelRes ) ) ? //
getClass().getResource( path.substring( labelResLen ) )
: null;
}
// -- begin methods for plugin registration/unregistration
/**
* This is an utility method. It is used to register the plugin service. Don't
* forget to call the {@link #unregister()} when the plugin is no longer
* needed.
*
* @param bc the bundle context used for service registration.
* @return self
*/
public final SimpleWebConsolePlugin register( BundleContext bc )
{
synchronized ( regLock )
{
activate( bc ); // don't know why this is needed!
Hashtable props = new Hashtable();
props.put( WebConsoleConstants.PLUGIN_LABEL, getLabel() );
props.put( WebConsoleConstants.PLUGIN_TITLE, getTitle() );
if ( getCategory() != null )
{
props.put( WebConsoleConstants.PLUGIN_CATEGORY, getCategory() );
}
reg = bc.registerService( "javax.servlet.Servlet", this, props ); //$NON-NLS-1$
}
return this;
}
/**
* An utility method that removes the service, registered by the
* {@link #register(BundleContext)} method.
*/
public final void unregister()
{
synchronized ( regLock )
{
deactivate(); // is this needed?
if ( reg != null )
reg.unregister();
reg = null;
}
}
// -- end methods for plugin registration/unregistration
// -- begin methods for obtaining services
/**
* Gets the service with the specified class name. Will create a new
* {@link ServiceTracker} if the service is not already got.
*
* @param serviceName the service name to obtain
* @return the service or null if missing.
*/
public final Object getService( String serviceName )
{
ServiceTracker serviceTracker = ( ServiceTracker ) services.get( serviceName );
if ( serviceTracker == null )
{
serviceTracker = new ServiceTracker( getBundleContext(), serviceName, null );
serviceTracker.open();
services.put( serviceName, serviceTracker );
}
return serviceTracker.getService();
}
/**
* This method will close all service trackers, created by
* {@link #getService(String)} method. If you override this method, don't
* forget to call the super.
*
* @see org.apache.felix.webconsole.AbstractWebConsolePlugin#deactivate()
*/
public void deactivate()
{
for ( Iterator ti = services.values().iterator(); ti.hasNext(); )
{
ServiceTracker tracker = ( ServiceTracker ) ti.next();
tracker.close();
ti.remove();
}
super.deactivate();
}
}