O problema estava acontecendo devido ao pequeno valor de
time_out variável no servidor MySQL. Na minha situação,
time_out foi definido como 1 minuto. Usando C3PO mecanismo de pooling podemos otimizar JDBC . Baixar c3p0 -> http://sourceforge.net/projects/c3p0/
Estou usando o hibernate 3.0 .
hibernate.cfg.xml
<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://databasehost:3306/databasename</property>
<property name="connection.username">user</property>
<property name="connection.password">psw</property>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="hibernate.hbm2ddl.auto">update</property>
<property name="show_sql">false</property>
<!-- Hibernate c3p0 settings-->
<property name="connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
<property name="hibernate.c3p0.acquire_increment">3</property>
<property name="hibernate.c3p0.idle_test_period">10</property>
<property name="hibernate.c3p0.min_size">5</property>
<property name="hibernate.c3p0.max_size">75</property>
<property name="hibernate.c3p0.max_statements">10</property>
<property name="hibernate.c3p0.timeout">50</property>
<property name="hibernate.c3p0.preferredTestQuery">select 1</property>
<property name="hibernate.c3p0.testConnectionOnCheckout">true</property>
<!-- Mapping files -->
<mapping class="xxx.xxx.xxx.xxx" />
<mapping class="xxx.xxx.xxx.xxx" />
<mapping class="xxx.xxx.xxx.xxx" />
<mapping class="xxx.xxx.xxx.xxx" />
</session-factory>
</hibernate-configuration>
PersistenceManager.java
import java.io.PrintStream;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.cfg.Configuration;
public class PersistenceManager
{
private static SessionFactory sessionFactory = null;
private static PersistenceManager singleton = null;
public static PersistenceManager getInstance()
{
if (singleton == null)
{
singleton = new PersistenceManager();
}
return singleton;
}
public SessionFactory getSessionFactory()
{
if (sessionFactory == null)
createSessionFactory();
return sessionFactory;
}
protected void createSessionFactory()
{
sessionFactory = new AnnotationConfiguration().configure()
.buildSessionFactory();
}
public void destroySessionFactory()
{
if (sessionFactory != null)
{
sessionFactory.close();
sessionFactory = null;
}
}
}
Exemplo 1:
import org.hibernate.HibernateException;
import org.hibernate.Query;
import org.hibernate.Session;
public Users Login( String username, String password)
{
Session session = null;
try
{
String hql = "select u from Users u where u.username like :p1 and u.password like :p2";
session = PersistenceManager.getInstance().getSessionFactory().openSession();
Query q = session.createQuery(hql)
.setParameter("p1", username)
.setParameter("p2", password);
if (q.list().size() == 0)
{
session.close();
return new Users();
}
Users user = (Users)q.list().get(0);
session.close();
return user;
}
catch (Exception e)
{
session.close();
}
}
Exemplo 2:
import org.hibernate.HibernateException;
import org.hibernate.Query;
import org.hibernate.Session;
public String Registration(Users u) {
Session session = null;
try
{
String hql = "select u from Users u where u.username like :p1";
session = PersistenceManager.getInstance().getSessionFactory().openSession();
Query q = session.createQuery(hql).setParameter("p1", u.getUsername());
if (q.list().size() == 0)
{
session.beginTransaction();
session.persist(u);
session.getTransaction().commit();
session.close();
return new Boolean(true).toString();
}
session.close();
return new Boolean(false).toString();
}
catch (Exception e)
{
return e.toString();
}
}
