import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class HibernateUtil {
	private static SessionFactory sessionFactory;
	
	private HibernateUtil() {}
	
	static{
		try{
			sessionFactory = new Configuration().configure().buildSessionFactory();
		}catch(Throwable e){
			throw new ExceptionInInitializerError(e);
		}
	}
	
	public static SessionFactory getSessionFactory(){
		return sessionFactory;
	}
}

Exception in thread "main" java.lang.ExceptionInInitializerError
	at main.java.util.HibernateUtil.<clinit>(HibernateUtil.java:15)
	at main.java.dao.impl.BookDaoImpl.getBooks(BookDaoImpl.java:64)
	at main.java.general.Project.main(Project.java:30)
Caused by: org.hibernate.HibernateException: Could not parse configuration: /hibernate.cfg.xml
	at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:2165)
	at org.hibernate.cfg.Configuration.configure(Configuration.java:2077)
	at org.hibernate.cfg.Configuration.configure(Configuration.java:2056)
	at main.java.util.HibernateUtil.<clinit>(HibernateUtil.java:13)
	... 2 more
Caused by: org.dom4j.DocumentException: Server returned HTTP response code: 503 for URL: http://www.hibernate.sourceforge.net/hibernate-configuration-3.0.dtd Nested exception: Server returned HTTP response code: 503 for URL: http://www.hibernate.sourceforge.net/hibernate-configuration-3.0.dtd
	at org.dom4j.io.SAXReader.read(SAXReader.java:484)
	at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:2157)
	... 5 more

Caused by: org.hibernate.HibernateException: Could not parse configuration: /hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://www.hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
	<session-factory>
		<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
		<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
		<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/testhibernate</property>
		<property name="hibernate.connection.username">****</property>
		<property name="hibernate.connection.password">****</property>
		
		<mapping resource="book.hbm.xml"/>
		<mapping resource="author.hbm.xml"/>
		
	</session-factory>
</hibernate-configuration>