Java/Hibernate/Hibernate Session

Session Disconnect And Reconnect

/////////////////////////////////////////////////////////////////////////
import java.util.*;
import java.sql.*;
import org.hibernate.*;
import org.hibernate.cfg.*;
import org.hibernate.criterion.*;
public class Main {
  
  public static void main(String[] args) {
    HibernateUtil.setup("create table Supplier ( id int, name VARCHAR);");
    HibernateUtil.setup("create table Product ( id int, name VARCHAR, description VARCHAR, price double,supplierId int);");
    
    prepareData();
        SessionFactory factory = new Configuration().configure().buildSessionFactory();
        Session session = factory.openSession();
        Query query = session.createQuery("from Product order by name");
        List list = query.list();
        Iterator i = list.iterator();
        while(i.hasNext()) {
           Product p = (Product)i.next();
           System.out.println(p.getName());
        }
        System.out.println("Step 1.");
        //session.close();
        
        session.disconnect();
        session.reconnect();
        query = session.createQuery("from Product order by name");
        list = query.list();
        i = list.iterator();
        while(i.hasNext()) {
           Product p = (Product)i.next();
           System.out.println(p.getName());
        }
        System.out.println("Step 2.");
    
        HibernateUtil.checkData("select * from Supplier");
        HibernateUtil.checkData("select * from Product");
  }
    static public void displaySupplierList(List list) {
        Iterator iter = list.iterator();
        if (!iter.hasNext()) {
            System.out.println("No suppliers to display.");
            return;
        }        
        while (iter.hasNext()) {
            Supplier supplier = (Supplier) iter.next();
            String msg = supplier.getName();
            System.out.println(msg);
        }
    }
 

  private static void prepareData(){
        Session session = HibernateUtil.currentSession();
        Supplier supplier1 = new Supplier();
        supplier1.setName("Supplier Name 1");
        session.save(supplier1);
        
        Supplier supplier2 = new Supplier();
        supplier2.setName("Supplier Name 2");
        session.save(supplier2);        
        
        Product product1 = new Product("Product 1","Name for Product 1", 2.0);
        product1.setSupplier(supplier1);
        supplier1.getProducts().add(product1);
        session.save(product1);
        
        Product product12 = new Product("Product 2","Name for Product 2", 22.0);
        product12.setSupplier(supplier1);
        supplier1.getProducts().add(product12);        
        session.save(product12);
        
        Product product2 = new Product("Product 3", "Name for Product 3", 30.0);
        product2.setSupplier(supplier2);
        supplier2.getProducts().add(product2);
        session.save(product2);
        
        session.flush();
        HibernateUtil.closeSession();
  }
}


/////////////////////////////////////////////////////////////////////////
public class Product
{
    private int id;
    private Supplier supplier;
    
    private String name;
    private String description;
    private double price;
    
    public Product()
    {
        super();
    }
    
    public Product(String name, String description, double price)
    {
        super();
        this.name = name;
        this.description = description;
        this.price = price;
    }
    
    public String getDescription()
    {
        return description;
    }
    public void setDescription(String description)
    {
        this.description = description;
    }
    public int getId()
    {
        return id;
    }
    public void setId(int id)
    {
        this.id = id;
    }
    public String getName()
    {
        return name;
    }
    public void setName(String name)
    {
        this.name = name;
    }
 
    public Supplier getSupplier()
    {
        return supplier;
    }
    public void setSupplier(Supplier supplier)
    {
        this.supplier = supplier;
    }
    
    public double getPrice()
    {
        return price;
    }
    public void setPrice(double price)
    {
        this.price = price;
    }
}

/////////////////////////////////////////////////////////////////////////
import java.util.ArrayList;
import java.util.List;
public class Supplier
{
    private int id;
    private String name;
    private List products = new ArrayList();
    
    public int getId()
    {
        return id;
    }
    public void setId(int id)
    {
        this.id = id;
    }
    public String getName()
    {
        return name;
    }
    public void setName(String name)
    {
        this.name = name;
    }
    public List getProducts()
    {
        return products;
    }
    public void setProducts(List products)
    {
        this.products = products;
    }
}

Use Two Sessions

/////////////////////////////////////////////////////////////////////////
import java.util.*;
import org.hibernate.*;
import org.hibernate.criterion.*;
public class Main {
  
  
  public static void main(String[] args) {
    HibernateUtil.setup("create table EVENTS ( uid int, name VARCHAR, start_Date date, duration int);");
    
    // hibernate code start
        HibernateFactory.buildSessionFactory();
        Session session = HibernateFactory.openSession();
        Session session2 = HibernateFactory.openSession();
        Event event = new Event();
        event.setName("Name");
        session.save(event);
        session.flush();
        Event event2 = (Event) session2.load(Event.class, event.getId());
        System.out.println(event2.getName());
        
        HibernateUtil.checkData("select uid, name from events");        
    // hibernate code end
  }
  
}

/////////////////////////////////////////////////////////////////////////
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping >
    <class name="Event" table="events">
        <id name="id" column="uid" type="long">
            <generator class="increment"/>
        </id>
        <property name="name" type="string"/>
        <property name="startDate" column="start_date" type="date"/>
        <property name="duration" type="integer"/>
    </class>
</hibernate-mapping>


/////////////////////////////////////////////////////////////////////////
import java.io.Serializable;
import java.util.Date;
import java.util.Set;
import java.util.LinkedHashSet;
public class Event implements Serializable {
    private Long id;
    private int duration;
    private String name;
    private Date startDate;
    public Event() {
    }
    public Event(String name) {
        this.name = name;
    }
    /**
     * @hibernate.id generator-class="native" column="uid"
     * @return
     */
    public Long getId() { return id; }
    public void setId(Long id) { this.id = id; }
    /**
     * @hibernate.property column="name"
     * @return
     */
    public String getName() { return name; }
    public void setName(String name) { this.name = name;   }
    /**
     * @hibernate.property column="start_date"
     * @return
     */
    public Date getStartDate() { return startDate; }
    public void setStartDate(Date startDate) { this.startDate = startDate; }
    /**
     * @hibernate.property column="duration"
     * @return
     */
    public int getDuration() { return duration; }
    public void setDuration(int duration) { this.duration = duration; }
}

/////////////////////////////////////////////////////////////////////////
/**
 * Represents Exceptions thrown by the Data Access Layer.
 */
public class DataAccessLayerException extends RuntimeException {
    public DataAccessLayerException() {
    }
    public DataAccessLayerException(String message) {
        super(message);
    }
    public DataAccessLayerException(Throwable cause) {
        super(cause);
    }
    public DataAccessLayerException(String message, Throwable cause) {
        super(message, cause);
    }
}