/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2003-2008, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
package org.geotools.data;
import java.io.IOException;
import java.util.Arrays;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.logging.Logger;
import org.geotools.factory.FactoryCreator;
import org.geotools.factory.FactoryRegistry;
import org.opengis.feature.Feature;
import org.opengis.feature.type.FeatureType;
/**
* Enable programs to find all available datastore implementations.
*
* <p>
* In order to be located by this finder datasources must provide an
* implementation of the {@link DataStoreFactorySpi} interface.
* </p>
*
* <p>
* In addition to implementing this interface datasouces should have a services
* file:<br/><code>META-INF/services/org.geotools.data.DataStoreFactorySpi</code>
* </p>
*
* <p>
* The file should contain a single line which gives the full name of the
* implementing class.
* </p>
*
* <p>
* Example:<br/><code>org.geotools.data.mytype.MyTypeDataStoreFacotry</code>
* </p>
*
*
* @source $URL$
*/
public final class DataStoreFinder {
/** The logger for the filter module. */
protected static final Logger LOGGER = org.geotools.util.logging.Logging.getLogger("org.geotools.data");
/**
* The service registry for this manager. Will be initialized only when
* first needed.
*/
private static FactoryRegistry registry;
//Singleton pattern
private DataStoreFinder() {
}
/**
* Checks each available datasource implementation in turn and returns the
* first one which claims to support the resource identified by the params
* object.
*
* @param params A Map object which contains a defenition of the resource
* to connect to. for file based resources the property 'url'
* should be set within this Map.
*
* @return The first datasource which claims to process the required
* resource, returns null if none can be found.
*
* @throws IOException If a suitable loader can be found, but it can not be
* attached to the specified resource without errors.
*/
public static synchronized DataStore getDataStore(Map params) throws IOException {
Iterator<DataStoreFactorySpi> ps = getAvailableDataStores();
DataAccess<? extends FeatureType, ? extends Feature> dataStore;
dataStore = DataAccessFinder.getDataStore(params, ps);
return (DataStore) dataStore;
}
/**
* Finds all implemtaions of DataStoreFactory which have registered using
* the services mechanism, regardless weather it has the appropriate
* libraries on the classpath.
*
* @return An iterator over all discovered datastores which have registered
* factories
*/
public static synchronized Iterator<DataStoreFactorySpi> getAllDataStores() {
return DataAccessFinder.getAllDataStores(getServiceRegistry(), DataStoreFactorySpi.class);
}
/**
* Finds all implemtaions of DataStoreFactory which have registered using
* the services mechanism, and that have the appropriate libraries on the
* classpath.
*
* @return An iterator over all discovered datastores which have registered
* factories, and whose available method returns true.
*/
public static synchronized Iterator<DataStoreFactorySpi> getAvailableDataStores() {
Set<DataStoreFactorySpi> availableDS;
FactoryRegistry serviceRegistry = getServiceRegistry();
availableDS = DataAccessFinder.getAvailableDataStores(serviceRegistry, DataStoreFactorySpi.class);
return availableDS.iterator();
}
/**
* Returns the service registry. The registry will be created the first time
* this method is invoked.
*/
private static FactoryRegistry getServiceRegistry() {
assert Thread.holdsLock(DataStoreFinder.class);
if (registry == null) {
registry = new FactoryCreator(Arrays
.asList(new Class<?>[] { DataStoreFactorySpi.class }));
}
return registry;
}
/**
* Scans for factory plug-ins on the application class path. This method is
* needed because the application class path can theoretically change, or
* additional plug-ins may become available. Rather than re-scanning the
* classpath on every invocation of the API, the class path is scanned
* automatically only on the first invocation. Clients can call this method
* to prompt a re-scan. Thus this method need only be invoked by
* sophisticated applications which dynamically make new plug-ins available
* at runtime.
*/
public static synchronized void scanForPlugins() {
getServiceRegistry().scanForPlugins();
}
/**
* Resets the factory finder and prepares for a new full scan of the SPI subsystems
*/
public static void reset() {
FactoryRegistry copy = registry;
registry = null;
if(copy != null) {
copy.deregisterAll();
}
}
}