javax.persistence.spi.PersistenceProviderResolverHolder Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*/
//
// This source code implements specifications defined by the Java
// Community Process. In order to remain compliant with the specification
// DO NOT add / change / or delete method signatures!
//
package javax.persistence.spi;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.List;
import java.util.ServiceLoader;
import java.util.WeakHashMap;
import javax.persistence.PersistenceException;
/**
* Contains Geronimo implemented code as required by the JPA spec.
*
* Finds/Creates the global {@link javax.persistence.spi.PersistenceProviderResolver}
*
* Implementations must be thread-safe.
*
* @since Java Persistence 2.0
*/
public class PersistenceProviderResolverHolder {
private static PersistenceProviderResolver persistenceResolver =
new DefaultPersistenceProviderResolver();
public static PersistenceProviderResolver getPersistenceProviderResolver() {
return persistenceResolver;
}
public static void setPersistenceProviderResolver(PersistenceProviderResolver resolver) {
if (persistenceResolver != null) {
persistenceResolver.clearCachedProviders();
persistenceResolver = null;
}
if (resolver != null) {
persistenceResolver = resolver;
} else {
// handle removing a resolver for OSGi environments
persistenceResolver = new DefaultPersistenceProviderResolver();
}
}
/*
* (non-Javadoc) Default implementation of a PersistenceProviderResolver
* to use when none are provided.
*
* Geronimo implementation specific code.
*/
private static class DefaultPersistenceProviderResolver implements PersistenceProviderResolver {
// cache of providers per class loader
private volatile WeakHashMap> providerCache =
new WeakHashMap>();
/*
* (non-Javadoc)
*
* @see javax.persistence.spi.PersistenceProviderResolver#getPersistenceProviders()
*/
public List getPersistenceProviders() {
// get our class loader
ClassLoader cl = PrivClassLoader.get(null);
if (cl == null)
cl = PrivClassLoader.get(DefaultPersistenceProviderResolver.class);
// use any previously cached providers
List providers = providerCache.get(cl);
if (providers == null) {
// need to discover and load them for this class loader
providers = new ArrayList();
try {
// add each one to our list
for (PersistenceProvider provider : ServiceLoader.load(PersistenceProvider.class, cl)) {
providers.add(provider);
}
// cache the discovered providers
providerCache.put(cl, providers);
} catch (Exception e) {
throw new PersistenceException("Failed to load provider from META-INF/services", e);
}
}
// caller must handle the case of no providers found
return providers;
}
/*
* (non-Javadoc)
*
* @see javax.persistence.spi.PersistenceProviderResolver#clearCachedProviders()
*/
public void clearCachedProviders() {
providerCache.clear();
}
private static class PrivClassLoader implements PrivilegedAction {
private final Class> c;
public static ClassLoader get(Class> c) {
final PrivClassLoader action = new PrivClassLoader(c);
if (System.getSecurityManager() != null)
return AccessController.doPrivileged(action);
else
return action.run();
}
private PrivClassLoader(Class> c) {
this.c = c;
}
public ClassLoader run() {
if (c != null)
return c.getClassLoader();
else
return Thread.currentThread().getContextClassLoader();
}
}
}
}
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