/*
* Copyright 2006 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.felix.examples.spellcheckservice.impl;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.StringTokenizer;
import org.apache.felix.examples.dictionaryservice.DictionaryService;
import org.apache.felix.examples.spellcheckservice.SpellCheckService;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceEvent;
import org.osgi.framework.ServiceListener;
import org.osgi.framework.ServiceReference;
import org.osgi.framework.ServiceRegistration;
/**
* This class implements a bundle that implements a spell check service. The
* spell check service uses all available dictionary services to check for the
* existence of words in a given sentence. This bundle not only monitors the
* dynamic availability of dictionary services, but it manages the aggregation
* of all available dictionary services as they arrive and depart. The spell
* check service is only registered if there are dictionary services available,
* thus the spell check service will appear and disappear as dictionary services
* appear and disappear, respectively.
*
* @author <a href="mailto:dev@felix.apache.org">Felix Project Team</a>
*/
public class Activator implements BundleActivator, ServiceListener
{
// Bundle's context.
private BundleContext m_context = null;
// List of available dictionary service references.
private ArrayList m_refList = new ArrayList();
// Maps service references to service objects.
private HashMap m_refToObjMap = new HashMap();
// The spell check service registration.
private ServiceRegistration m_reg = null;
/**
* Implements BundleActivator.start(). Adds itself as a service listener and
* queries for all currently available dictionary services. Any available
* dictionary services are added to the service reference list. If
* dictionary services are found, then the spell check service is
* registered.
*
* @param context the framework context for the bundle.
*/
public void start( BundleContext context ) throws Exception
{
m_context = context;
// Listen for events pertaining to dictionary services.
m_context.addServiceListener( this, "(&(objectClass=" + DictionaryService.class.getName() + ")"
+ "(Language=*))" );
// Query for all dictionary services.
ServiceReference[] refs = m_context.getServiceReferences( DictionaryService.class.getName(), "(Language=*)" );
// Add any dictionaries to the service reference list.
if ( refs != null )
{
// Lock the list.
synchronized ( m_refList )
{
for ( int i = 0; i < refs.length; i++ )
{
// Get the service object.
Object service = m_context.getService( refs[i] );
// Make that the service is not being duplicated.
if ( ( service != null ) && ( m_refToObjMap.get( refs[i] ) == null ) )
{
// Add to the reference list.
m_refList.add( refs[i] );
// Map reference to service object for easy look up.
m_refToObjMap.put( refs[i], service );
}
}
// Register spell check service if there are any dictionary services.
if ( m_refList.size() > 0 )
{
m_reg = m_context.registerService( SpellCheckService.class.getName(),
new SpellCheckServiceImpl(), null );
}
}
}
}
/**
* Implements BundleActivator.stop(). Does nothing since the framework will
* automatically unregister any registered services, release any used
* services, and remove any event listeners.
*
* @param context
* the framework context for the bundle.
*/
public void stop( BundleContext context )
{
// NOTE: The services automatically released.
}
/**
* Implements ServiceListener.serviceChanged(). Monitors the arrival and
* departure of dictionary services, adding and removing them from the
* service reference list, respectively. In the case where no more
* dictionary services are available, the spell check service is registered.
* As soon as any dictionary spell check becomes available, the spell check
* service is reregistered.
*
* @param event the fired service event.
*/
public void serviceChanged( ServiceEvent event )
{
// Add the new dictionary service to the service list.
if ( event.getType() == ServiceEvent.REGISTERED )
{
synchronized ( m_refList )
{
// Get the service object.
Object service = m_context.getService( event.getServiceReference() );
// Make that the service is not being duplicated.
if ( ( service != null ) && ( m_refToObjMap.get( event.getServiceReference() ) == null ) )
{
// Add to the reference list.
m_refList.add( event.getServiceReference() );
// Map reference to service object for easy look up.
m_refToObjMap.put( event.getServiceReference(), service );
// Register spell check service if necessary.
if ( m_reg == null )
{
m_reg = m_context.registerService( SpellCheckService.class.getName(),
new SpellCheckServiceImpl(), null );
}
}
else if ( service != null )
{
m_context.ungetService( event.getServiceReference() );
}
}
}
// Remove the departing service from the service list.
else if ( event.getType() == ServiceEvent.UNREGISTERING )
{
synchronized ( m_refList )
{
// Make sure the service is in the list.
if ( m_refToObjMap.get( event.getServiceReference() ) != null )
{
// Unget the service object.
m_context.ungetService( event.getServiceReference() );
// Remove service reference.
m_refList.remove( event.getServiceReference() );
// Remove service reference from map.
m_refToObjMap.remove( event.getServiceReference() );
// If there are no more dictionary services,
// then unregister spell check service.
if ( m_refList.size() == 0 )
{
m_reg.unregister();
m_reg = null;
}
}
}
}
}
/**
* A private inner class that implements a spell check service; see
* SpellCheckService for details of the service.
*/
private class SpellCheckServiceImpl implements SpellCheckService
{
/**
* Implements SpellCheckService.check(). Checks the given passage for
* misspelled words.
*
* @param passage
* the passage to spell check.
* @return An array of misspelled words or null if no words are
* misspelled.
*/
public String[] check( String passage )
{
// No misspelled words for an empty string.
if ( ( passage == null ) || ( passage.length() == 0 ) )
{
return null;
}
ArrayList errorList = new ArrayList();
// Tokenize the passage using spaces and punctionation.
StringTokenizer st = new StringTokenizer( passage, " ,.!?;:" );
// Lock the service list.
synchronized ( m_refList )
{
// Loop through each word in the passage.
while ( st.hasMoreTokens() )
{
String word = st.nextToken();
boolean correct = false;
// Check each available dictionary for the current word.
for ( int i = 0; ( !correct ) && ( i < m_refList.size() ); i++ )
{
DictionaryService dictionary = ( DictionaryService ) m_refToObjMap.get( m_refList.get( i ) );
if ( dictionary.checkWord( word ) )
{
correct = true;
}
}
// If the word is not correct, then add it
// to the incorrect word list.
if ( !correct )
{
errorList.add( word );
}
}
}
// Return null if no words are incorrect.
if ( errorList.size() == 0 )
{
return null;
}
// Return the array of incorrect words.
return ( String[] ) errorList.toArray( new String[errorList.size()] );
}
}
}