javax.persistence.Persistence Maven / Gradle / Ivy
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package javax.persistence;
// J2SE imports
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Set;
import java.util.Map;
import java.util.HashSet;
import java.util.Enumeration;
import java.net.URL;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
// persistence imports
import javax.persistence.spi.PersistenceProvider;
/**
* Bootstrap class that is used to obtain an {@link EntityManagerFactory}.
*
* @since Java Persistence 1.0
*/
public class Persistence {
public static final String PERSISTENCE_PROVIDER = "javax.persistence.spi.PeristenceProvider";
protected static final Set providers = new HashSet();
/**
* Create and return an EntityManagerFactory for the
* named persistence unit.
*
* @param persistenceUnitName The name of the persistence unit
* @return The factory that creates EntityManagers configured
* according to the specified persistence unit
*/
public static EntityManagerFactory createEntityManagerFactory(String persistenceUnitName) {
return createEntityManagerFactory(persistenceUnitName, null);
}
/**
* Create and return an EntityManagerFactory for the
* named persistence unit using the given properties.
*
* @param persistenceUnitName The name of the persistence unit
* @param properties Additional properties to use when creating the
* factory. The values of these properties override any values
* that may have been configured elsewhere.
* @return The factory that creates EntityManagers configured
* according to the specified persistence unit.
*/
public static EntityManagerFactory createEntityManagerFactory(
String persistenceUnitName, Map properties) {
EntityManagerFactory emf = null;
if (providers.size() == 0) {
try{
findAllProviders();
} catch (IOException exc){};
}
for (PersistenceProvider provider : providers) {
emf = provider.createEntityManagerFactory(persistenceUnitName, properties);
if (emf != null){
break;
}
}
if (emf == null) {
throw new PersistenceException("No Persistence provider for EntityManager named " + persistenceUnitName);
}
return emf;
}
// Helper methods
private static void findAllProviders() throws IOException {
ClassLoader loader = Thread.currentThread().getContextClassLoader();
Enumeration resources =
loader.getResources("META-INF/services/" + PersistenceProvider.class.getName());
Set names = new HashSet();
while (resources.hasMoreElements()) {
URL url = resources.nextElement();
InputStream is = url.openStream();
try {
names.addAll(providerNamesFromReader(new BufferedReader(new InputStreamReader(is))));
} finally {
is.close();
}
}
for (String s : names) {
try{
providers.add((PersistenceProvider)loader.loadClass(s).newInstance());
} catch (ClassNotFoundException exc){
} catch (InstantiationException exc){
} catch (IllegalAccessException exc){
}
}
}
private static final Pattern nonCommentPattern = Pattern.compile("^([^#]+)");
private static Set providerNamesFromReader(BufferedReader reader) throws IOException {
Set names = new HashSet();
String line;
while ((line = reader.readLine()) != null) {
line = line.trim();
Matcher m = nonCommentPattern.matcher(line);
if (m.find()) {
names.add(m.group().trim());
}
}
return names;
}
}