| /* |
| * 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.dictionaryclient2; |
| |
| |
| import java.io.BufferedReader; |
| import java.io.InputStreamReader; |
| |
| import org.apache.felix.examples.dictionaryservice.DictionaryService; |
| |
| import org.osgi.framework.BundleActivator; |
| import org.osgi.framework.BundleContext; |
| import org.osgi.framework.InvalidSyntaxException; |
| import org.osgi.framework.ServiceEvent; |
| import org.osgi.framework.ServiceListener; |
| import org.osgi.framework.ServiceReference; |
| |
| |
| /** |
| * This class implements a bundle that uses a dictionary service to check for |
| * the proper spelling of a word by checking for its existence in the |
| * dictionary. This bundle is more complex than the bundle in Example 3 because |
| * it monitors the dynamic availability of the dictionary services. In other |
| * words, if the service it is using departs, then it stops using it gracefully, |
| * or if it needs a service and one arrives, then it starts using it |
| * automatically. As before, the bundle uses the first service that it finds and |
| * uses the calling thread of the start() method to read words from standard |
| * input. You can stop checking words by entering an empty line, but to start |
| * checking words again you must stop and then restart the bundle. |
| * |
| * @author <a href="mailto:felix-dev@incubator.apache.org">Felix Project Team</a> |
| */ |
| public class Activator implements BundleActivator, ServiceListener |
| { |
| // Bundle's context. |
| private BundleContext m_context = null; |
| |
| // The service reference being used. |
| private ServiceReference m_ref = null; |
| |
| // The service object being used. |
| private DictionaryService m_dictionary = null; |
| |
| |
| /** |
| * Implements BundleActivator.start(). Adds itself as a listener for service |
| * events, then queries for available dictionary services. If any |
| * dictionaries are found it gets a reference to the first one available and |
| * then starts its "word checking loop". If no dictionaries are found, then |
| * it just goes directly into its "word checking loop", but it will not be |
| * able to check any words until a dictionary service arrives; any arriving |
| * dictionary service will be automatically used by the client if a |
| * dictionary is not already in use. Once it has dictionary, it reads words |
| * from standard input and checks for their existence in the dictionary that |
| * it is using. (NOTE: It is very bad practice to use the calling thread to |
| * perform a lengthy process like this; this is only done for the purpose of |
| * the tutorial.) |
| * |
| * @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 any service references matching any language. |
| ServiceReference[] refs = m_context.getServiceReferences( DictionaryService.class.getName(), "(Language=*)" ); |
| |
| // If we found any dictionary services, then just get |
| // a reference to the first one so we can use it. |
| if ( refs != null ) |
| { |
| m_ref = refs[0]; |
| m_dictionary = ( DictionaryService ) m_context.getService( m_ref ); |
| } |
| |
| try |
| { |
| System.out.println( "Enter a blank line to exit." ); |
| String word = ""; |
| BufferedReader in = new BufferedReader( new InputStreamReader( System.in ) ); |
| |
| // Loop endlessly. |
| while ( true ) |
| { |
| // Ask the user to enter a word. |
| System.out.print( "Enter word: " ); |
| word = in.readLine(); |
| |
| // If the user entered a blank line, then |
| // exit the loop. |
| if ( word.length() == 0 ) |
| { |
| break; |
| } |
| // If there is no dictionary, then say so. |
| else if ( m_dictionary == null ) |
| { |
| System.out.println( "No dictionary available." ); |
| } |
| // Otherwise print whether the word is correct or not. |
| else if ( m_dictionary.checkWord( word ) ) |
| { |
| System.out.println( "Correct." ); |
| } |
| else |
| { |
| System.out.println( "Incorrect." ); |
| } |
| } |
| } |
| catch ( Exception ex ) |
| { |
| } |
| } |
| |
| |
| /** |
| * Implements BundleActivator.stop(). Does nothing since the framework will |
| * automatically unget any used services. |
| * |
| * @param context the framework context for the bundle. |
| */ |
| public void stop( BundleContext context ) |
| { |
| // NOTE: The service is automatically released. |
| } |
| |
| |
| /** |
| * Implements ServiceListener.serviceChanged(). Checks to see if the service |
| * we are using is leaving or tries to get a service if we need one. |
| * |
| * @param event |
| * the fired service event. |
| */ |
| public void serviceChanged( ServiceEvent event ) |
| { |
| // If a dictionary service was registered, see if we |
| // need one. If so, get a reference to it. |
| if ( event.getType() == ServiceEvent.REGISTERED ) |
| { |
| if ( m_ref == null ) |
| { |
| // Get a reference to the service object. |
| m_ref = event.getServiceReference(); |
| m_dictionary = ( DictionaryService ) m_context.getService( m_ref ); |
| } |
| } |
| // If a dictionary service was unregistered, see if it |
| // was the one we were using. If so, unget the service |
| // and try to query to get another one. |
| else if ( event.getType() == ServiceEvent.UNREGISTERING ) |
| { |
| if ( event.getServiceReference() == m_ref ) |
| { |
| // Unget service object and null references. |
| m_context.ungetService( m_ref ); |
| m_ref = null; |
| m_dictionary = null; |
| |
| // Query to see if we can get another service. |
| ServiceReference[] refs = null; |
| |
| try |
| { |
| refs = m_context.getServiceReferences( DictionaryService.class.getName(), "(Language=*)" ); |
| } |
| catch ( InvalidSyntaxException e ) |
| { |
| e.printStackTrace(); |
| } |
| |
| if ( refs != null ) |
| { |
| // Get a reference to the first service object. |
| m_ref = refs[0]; |
| m_dictionary = ( DictionaryService ) m_context.getService( m_ref ); |
| } |
| } |
| } |
| } |
| } |