/*
* 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.jdbc.datasource;
import java.io.IOException;
import java.sql.Connection;
import java.sql.Statement;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.sql.DataSource;
import org.geotools.factory.FactoryCreator;
import org.geotools.factory.FactoryRegistry;
/**
* Enable programs to find all available {@link DataSourceFactorySpi} implementations.
*
* <p>
* In addition to implementing this interface data souces should have a services file:<br/><code>META-INF/services/org.geotools.data.jdbc.DataSourceFactorySpi</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.jdbc.DBCPDataSourceFactory</code>
* </p>
*
*
* @source $URL$
*/
public final class DataSourceFinder {
/** The logger for the filter module. */
protected static final Logger LOGGER = org.geotools.util.logging.Logging.getLogger("org.geotools.data.jdbc");
/**
* The service registry for this manager. Will be initialized only when first needed.
*/
private static FactoryRegistry registry;
// Singleton pattern
private DataSourceFinder() {
}
/**
* 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 DataSource getDataSource(Map params) throws IOException {
Iterator ps = getAvailableDataSources();
DataSourceFactorySpi fac;
while (ps.hasNext()) {
fac = (DataSourceFactorySpi) ps.next();
try {
if (fac.canProcess(params)) {
return fac.createDataSource(params);
}
} catch (Throwable t) {
/** The logger for the filter module. */
LOGGER.log(Level.WARNING, "Could not acquire " + fac.getDescription() + ":" + t, t);
// Protect against DataStores that don't carefully
// code canProcess
}
}
return null;
}
/**
* 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 UnWrapper getUnWrapper(Connection conn) throws IOException {
Iterator ps = getUnWrappers();
UnWrapper uw;
while (ps.hasNext()) {
uw = (UnWrapper) ps.next();
try {
if (uw.canUnwrap(conn)) {
return uw;
}
} catch (Throwable t) {
/** The logger for the filter module. */
LOGGER.log(Level.WARNING, "Could not test " + uw
+ " for unwrapping abilities agaist " + conn, t);
// Protect against DataStores that don't carefully
// code canProcess
}
}
return null;
}
/**
* Checks each available {@link UnWrapper} 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 UnWrapper getUnWrapper(Statement st) throws IOException {
Iterator ps = getUnWrappers();
UnWrapper uw;
while (ps.hasNext()) {
uw = (UnWrapper) ps.next();
try {
if (uw.canUnwrap(st)) {
return uw;
}
} catch (Throwable t) {
/** The logger for the filter module. */
LOGGER.log(Level.WARNING, "Could not test " + uw
+ " for unwrapping abilities agaist " + st, t);
// Protect against DataStores that don't carefully
// code canProcess
}
}
return null;
}
/**
* 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 getAvailableDataSources() {
Set availableDS = new HashSet();
Iterator it = getServiceRegistry().getServiceProviders(DataSourceFactorySpi.class, null, null);
DataSourceFactorySpi dsFactory;
while (it.hasNext()) {
dsFactory = (DataSourceFactorySpi) it.next();
if (dsFactory.isAvailable()) {
availableDS.add(dsFactory);
}
}
return availableDS.iterator();
}
/**
* 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 getUnWrappers() {
Set availableDS = new HashSet();
return getServiceRegistry().getServiceProviders(UnWrapper.class, null, null);
}
/**
* Returns the service registry. The registry will be created the first time this method is
* invoked.
*/
private static FactoryRegistry getServiceRegistry() {
assert Thread.holdsLock(DataSourceFinder.class);
if (registry == null) {
registry = new FactoryCreator(Arrays.asList(new Class<?>[] { DataSourceFactorySpi.class,
UnWrapper.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();
}
}