org.bonitasoft.engine.builder.BuilderFactory Maven / Gradle / Ivy
The newest version!
/**
* Copyright (C) 2019 Bonitasoft S.A.
* Bonitasoft, 32 rue Gustave Eiffel - 38000 Grenoble
* 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.
* You should have received a copy of the GNU Lesser General Public License along with this
* program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth
* Floor, Boston, MA 02110-1301, USA.
**/
package org.bonitasoft.engine.builder;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
public class BuilderFactory {
private static final String BUILDER_FACTORIES_DEFAULT_FILE = "builder-factories.properties";
private static final String BUILDER_FACTORIES_EXTENSION_FILE = "builder-factories-ext.properties";
private final Map factoryCache;
private final Properties properties;
private static final Object MUTEX = new BuilderFactoryMutex();
private static BuilderFactory INSTANCE = null;
private BuilderFactory(final Properties properties) {
this.properties = properties;
factoryCache = new HashMap();
}
private static final class BuilderFactoryMutex {
}
public static BuilderFactory getInstance() {
if (INSTANCE == null) {
synchronized (MUTEX) {
// ensure we do not create many instances of this class
if (INSTANCE == null) {
URL defaultFileURL = null;
try {
defaultFileURL = BuilderFactory.class.getResource(BUILDER_FACTORIES_DEFAULT_FILE);
final Properties defaultProperties = getProperties(defaultFileURL);
final Properties allProperties = new Properties(defaultProperties);
final URL extensionFileURL = BuilderFactory.class.getResource(BUILDER_FACTORIES_EXTENSION_FILE);
if (extensionFileURL != null) {
final Properties extensionProperties = getProperties(extensionFileURL);
allProperties.putAll(extensionProperties);
}
INSTANCE = new BuilderFactory(allProperties);
} catch (final Exception e) {
throw new RuntimeException("Unable to load builder factories from : fileURL=" + defaultFileURL);
}
}
}
}
return INSTANCE;
}
private synchronized void cacheFactory(final String interfaceName, final String className) {
try {
if (className == null || "null".equals(className)) {
throw new Exception("Factory implementation of " + interfaceName + " is required.");
}
final Class clazz = Class.forName(className, true, Thread.currentThread().getContextClassLoader());
final Object factory = clazz.newInstance();
factoryCache.put(interfaceName, factory);
} catch (final Exception e) {
throw new RuntimeException(e);
}
}
public static T get(final Class clazz) {
final T factoryImplementation = getInstance().getInternalBuilderFactory(clazz);
if (factoryImplementation == null) {
throw new RuntimeException("No factory found for interface: " + clazz);
}
return factoryImplementation;
}
@SuppressWarnings("unchecked")
private T getInternalBuilderFactory(final Class clazz) {
if (!factoryCache.containsKey(clazz.getName())) {
cacheFactory(clazz.getName(), properties.getProperty(clazz.getName()));
}
return (T) factoryCache.get(clazz.getName());
}
public static Properties getProperties(final URL url) throws IOException {
final InputStreamReader reader = new InputStreamReader(url.openStream());
return getProperties(reader);
}
private static Properties getProperties(final Reader reader) throws IOException {
final Properties properties = new Properties();
try {
properties.load(reader);
return properties;
} finally {
reader.close();
}
}
}