org.geotools.data.DataStoreFinder Maven / Gradle / Ivy
/*
* 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.util.factory.FactoryCreator;
import org.geotools.util.factory.FactoryRegistry;
import org.opengis.feature.Feature;
import org.opengis.feature.type.FeatureType;
/**
* Enable programs to find all available datastore implementations.
*
* In order to be located by this finder datasources must provide an implementation of the {@link
* DataStoreFactorySpi} interface.
*
*
In addition to implementing this interface datasouces should have a services file:
* META-INF/services/org.geotools.data.DataStoreFactorySpi
*
*
The file should contain a single line which gives the full name of the implementing class.
*
*
Example:
* org.geotools.data.mytype.MyTypeDataStoreFacotry
*/
public final class DataStoreFinder {
/** The logger for the filter module. */
protected static final Logger LOGGER =
org.geotools.util.logging.Logging.getLogger(DataStoreFinder.class);
/** The service registry for this manager. Will be initialized only when first needed. */
private static volatile 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 ps = getAvailableDataStores();
DataAccess 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 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 getAvailableDataStores() {
Set 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();
}
}
}