package org.jrest4guice.persistence.jpa;
import java.net.URL;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
import com.google.inject.Singleton;
/**
*
* @author <a href="mailto:zhangyouqun@gmail.com">cnoss (QQ:86895156)</a>
*
*/
@Singleton
public class EntityManagerFactoryHolder {
private EntityManagerFactory entityManagerFactory;
private final ThreadLocal<EntityManagerInfo> entityManager = new ThreadLocal<EntityManagerInfo>();
public EntityManagerFactoryHolder() {
//注意:这一个版本只实现对一个persistence-unit的支持
try {
Set<String> units = new PersistenceXmlReader().doParse();
this.entityManagerFactory = Persistence
.createEntityManagerFactory(units.toArray()[0].toString());
} catch (Exception e) {
throw new RuntimeException("初始化 EntityManagerFactory 失败",e);
}
}
public EntityManagerFactory getEntityManagerFactory() {
return this.entityManagerFactory;
}
public EntityManagerInfo getEntityManagerInfo() {
EntityManagerInfo em = this.entityManager.get();
// 如果不存在，则创建一个新的
if (em == null) {
em = new EntityManagerInfo(getEntityManagerFactory().createEntityManager());
this.entityManager.set(em);
}
return em;
}
public void closeEntityManager() {
EntityManagerInfo em = this.entityManager.get();
if (em != null) {
try {
if (em.getEntityManager().isOpen())
em.getEntityManager().close();
} finally {
this.entityManager.remove();
}
}
}
static class PersistenceXmlReader {
class XmlHandler extends DefaultHandler {
private Set<String> units;
public XmlHandler() {
this.units = new HashSet<String>();
}
public Set<String> getUnits() {
return units;
}
public void startElement(String uri, String localName,
String qName, Attributes attributes) throws SAXException {
if (qName.equalsIgnoreCase("persistence-unit")) {
units.add(attributes.getValue("name").trim());
}
}
}
public Set<String> doParse() throws Exception {
XmlHandler handler = new XmlHandler();
SAXParserFactory factory = SAXParserFactory.newInstance();
factory.setNamespaceAware(false);
factory.setValidating(false);
SAXParser parser = factory.newSAXParser();
URL confURL = EntityManagerFactoryHolder.class.getClassLoader()
.getResource("META-INF/persistence.xml");
parser.parse(confURL.toString(), handler);
return handler.getUnits();
}
}
}