Java/Hibernate/Hibernate Transaction

Hibernate Transaction With Try Catch

/////////////////////////////////////////////////////////////////////////
import java.io.Serializable;
import java.util.*;
import org.hibernate.*;
import org.hibernate.cfg.*;
import org.hibernate.criterion.*;
import org.hibernate.event.*;
import org.hibernate.event.def.*;
public class Main {
   public static void main(String[] args) throws Exception {
      HibernateUtil.setup("create table grouptable (id int,name varchar);");    
      HibernateUtil.setup("create table story (id int,info varchar,idx int,parent_id int);");    
      Session session = HibernateUtil.currentSession();
      Group sp = new Group("Group Name");
     
      ArrayList list = new ArrayList();
      list.add(new Story("Story Name 1"));
      list.add(new Story("Story Name 2"));
      sp.setStories(list);
      Transaction transaction = null;
      try {
           transaction = session.beginTransaction();
           session.save(sp);
           transaction.rumit();
      } catch (Exception e) { 
           if (transaction != null) {
             transaction.rollback();
             throw e;
           }
      }  finally { 
           session.close();
      }
      HibernateUtil.checkData("select * from grouptable");
      HibernateUtil.checkData("select * from story");      
   }
}

/////////////////////////////////////////////////////////////////////////
import java.util.*;
public class Story {
  private int id;
  private String info;
  public Story(){
  }
  public Story(String info) {
    this.info = info;
  }
  public void setId(int i) {
    id = i;
  }
  public int getId() {
    return id;
  }
  public void setInfo(String n) {
    info = n;
  }
  public String getInfo() {
    return info;
  }
}

/////////////////////////////////////////////////////////////////////////
import java.util.*;
public class Group {
  private int id;
  private String name;
  private List stories;
  public Group(){
  }
  public Group(String name) {
    this.name = name;
  }
  public void setId(int i) {
    id = i;
  }
  public int getId() {
    return id;
  }
  public void setName(String n) {
    name = n;
  }
  public String getName() {
    return name;
  }
  public void setStories(List l) {
    stories = l;
  }
  public List getStories() {
    return stories;
  }
}

/////////////////////////////////////////////////////////////////////////
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping 
    PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN" 
    "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
    <class name="Group" table="grouptable">
         <id name="id" unsaved-value="0">
            <generator class="increment"/>
        </id>
        
        <list name="stories" cascade="all">
            <key column="parent_id"/>
            <index column="idx"/>
            <one-to-many class="Story"/>
        </list>
        <property name="name" type="string"/>
    </class>
    <class name="Story" 
         table="story">
         <id name="id" unsaved-value="0">
            <generator class="increment"/>
        </id>
          <property name="info"/>
    </class>
</hibernate-mapping>

/////////////////////////////////////////////////////////////////////////
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
public class HibernateUtil {
    public static final SessionFactory sessionFactory;
    static {
        try {
            // Create the SessionFactory from hibernate.cfg.xml
            sessionFactory = new Configuration().configure().buildSessionFactory();
        } catch (Throwable ex) {
            // Make sure you log the exception, as it might be swallowed
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }
    public static final ThreadLocal session = new ThreadLocal();
    public static Session currentSession() throws HibernateException {
        Session s = (Session) session.get();
        // Open a new Session, if this thread has none yet
        if (s == null) {
            s = sessionFactory.openSession();
            // Store it in the ThreadLocal variable
            session.set(s);
        }
        return s;
    }
    public static void closeSession() throws HibernateException {
        Session s = (Session) session.get();
        if (s != null)
            s.close();
        session.set(null);
    }
    
    static Connection conn; 
    static Statement st;
  public static void setup(String sql) {
    try {
      // Step 1: Load the JDBC driver.
      Class.forName("org.hsqldb.jdbcDriver");
      System.out.println("Driver Loaded.");
      // Step 2: Establish the connection to the database.
      String url = "jdbc:hsqldb:data/tutorial";
      conn = DriverManager.getConnection(url, "sa", "");
      System.out.println("Got Connection.");
      st = conn.createStatement();
      st.executeUpdate(sql);
    } catch (Exception e) {
      System.err.println("Got an exception! ");
      e.printStackTrace();
      System.exit(0);
    }
  }
  public static void checkData(String sql) {
    try {
      HibernateUtil.outputResultSet(st
          .executeQuery(sql));
//      conn.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
    public static void outputResultSet(ResultSet rs) throws Exception{
    ResultSetMetaData metadata = rs.getMetaData();
    int numcols = metadata.getColumnCount();
    String[] labels = new String[numcols]; 
    int[] colwidths = new int[numcols];
    int[] colpos = new int[numcols];
    int linewidth;
      for (int i = 0; i < numcols; i++) {
        labels[i] = metadata.getColumnLabel(i + 1); // get its label
        System.out.print(labels[i]+"  ");
    }
      System.out.println("------------------------");
    while (rs.next()) {
        for (int i = 0; i < numcols; i++) {
        Object value = rs.getObject(i + 1);
        if(value == null){
            System.out.print("       ");
        }else{
            System.out.print(value.toString().trim()+"   ");
        }
        
      }
        System.out.println("       ");
    }
    }
}

/////////////////////////////////////////////////////////////////////////
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD//EN"
    "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <!-- Database connection settings -->
        <property name="connection.driver_class">org.hsqldb.jdbcDriver</property>
        <property name="connection.url">jdbc:hsqldb:data/tutorial</property>
        <property name="connection.username">sa</property>
        <property name="connection.password"></property>
        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property>
        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.HSQLDialect</property>
        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>
        <!-- Mapping files -->
        <mapping resource="Group.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

Transaction Rollback Illustration

/////////////////////////////////////////////////////////////////////////
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();
        Product p = null;
        Session session = factory.openSession();
        Transaction tx = session.beginTransaction();
        p = (Product)session.createQuery("from Product where name="Product 1"").uniqueResult();
        tx.rumit();
        System.out.println("Username of p acquired from DB... " + p.getName());
        System.out.println("Begin transaction:");
        tx = session.beginTransaction();
        System.out.println("Change name of p");
        p.setName("quentin");
        System.out.println("Username of p before rollback... " + p.getName());
        tx.rollback();
        System.out.println("Username of p after rollback... " + p.getName());
        tx = session.beginTransaction();
        System.out.println("About to refresh p!");
        session.refresh(p);
        System.out.println("Username of p after refresh... " + p.getName());
        tx.rumit();
        System.out.println("Username of p after commit... " + p.getName());
    
        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;
    }
}


/////////////////////////////////////////////////////////////////////////
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping
   PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
   "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
   <class name="Supplier">
      <id name="id" type="int">
         <generator class="increment"/>
      </id>
      <property name="name" type="string"/>
      <bag name="products" inverse="true" cascade="all,delete-orphan">
        <key column="supplierId"/>
        <one-to-many class="Product"/>
      </bag>

   </class>
</hibernate-mapping>


/////////////////////////////////////////////////////////////////////////
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;
    }
}

/////////////////////////////////////////////////////////////////////////
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD//EN"
    "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <!-- Database connection settings -->
        <property name="connection.driver_class">org.hsqldb.jdbcDriver</property>
        <property name="connection.url">jdbc:hsqldb:data/tutorial</property>
        <property name="connection.username">sa</property>
        <property name="connection.password"></property>
        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property>
        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.HSQLDialect</property>
        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>
        <!-- Mapping files -->
        <mapping resource="Product.hbm.xml"/>
        <mapping resource="Supplier.hbm.xml"/>
    </session-factory>
</hibernate-configuration>