Java/Hibernate/Relation One to Many

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Mapping One To Many Set

   <source lang="java">

///////////////////////////////////////////////////////////////////////// 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 HighScores (id int,name varchar);");    
     HibernateUtil.setup("create table gamescores (id int,name varchar,score int,parent_id int);");    
     Session session = HibernateUtil.currentSession();
     HighScores sp = new HighScores("HighScores Name");
    
     HashSet set = new HashSet();
     set.add(new GameScore("GameScore Name 1", 3));
     set.add(new GameScore("GameScore Name 2", 2));
     sp.setGames(set);
     session.save(sp);
     session.flush();
     session.close();
     HibernateUtil.checkData("select * from HighScores");
     HibernateUtil.checkData("select * from gamescores");      
  }

}


///////////////////////////////////////////////////////////////////////// public class GameScore {

 private int id;
 private String name;
 private int score;
 
 public GameScore() {
 }
 public GameScore(String name, int score) {
   this.name = name;
   this.score = score;
 }
 public void setId(int i) {
   id = i;
 }
 public int getId() {
   return id;
 }
 public void setName(String s) {
   name = s;
 }
 public String getName() {
   return name;
 }
 public void setScore(int i) {
   score = i;
 }
 public int getScore() {
   return score;
 }
   public boolean equals(Object obj) {
       if (obj == null) return false;
       if (!this.getClass().equals(obj.getClass())) return false;
       
       GameScore obj2 = (GameScore)obj;
       if ((this.id == obj2.getId()) &&
           (this.name.equals(obj2.getName())) &&
           (this.score == obj2.getScore())
           ) {
           return true;
       }
       
   return false;
   }
   public int hashCode() {      
       int tmp = 0;
       tmp = (id + name + score).hashCode();
       return tmp;
   }

}

///////////////////////////////////////////////////////////////////////// import java.util.*; public class HighScores {

 private int id;
 private String name;
 private Set games;
 public HighScores() {
 }
 public HighScores(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 setGames(Set games) {
   this.games = games;
 }
 public Set getGames() {
   return games;
 }

}

///////////////////////////////////////////////////////////////////////// <?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="HighScores" table="highscores">
        <id name="id" unsaved-value="0">
           <generator class="increment"/>
       </id>
       <set name="games" cascade="all">
           <key column="parent_id"/>
           <one-to-many class="GameScore"/>
       </set>
       <property name="name" type="string"/>
   </class>
   
   <class name="GameScore" table="gamescores">
        <id name="id" unsaved-value="0">
           <generator class="increment"/>
       </id>
         <property name="name"/>
         <property name="score"/>
   </class>

</hibernate-mapping>

///////////////////////////////////////////////////////////////////////// <?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>
       
       <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>
       
       <property name="connection.pool_size">1</property>
       
       <property name="dialect">org.hibernate.dialect.HSQLDialect</property>
       
       <property name="show_sql">true</property>
       
       <mapping resource="HighScores.hbm.xml"/>
   </session-factory>

</hibernate-configuration>

///////////////////////////////////////////////////////////////////////// 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("       ");
   }
   }

}

      </source>
   
  
 
  



One To Many Bidirectional Map

   <source lang="java">

///////////////////////////////////////////////////////////////////////// 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");
    
     
     HashSet set = new HashSet();
     Story s = new Story("A Story");
     s.setParent(sp);
     set.add(s);
     sp.setStories(set);
     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 Group {

 private int id;
 private String name;
 private Set 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(Set l) {
   stories = l;
 }
 public Set getStories() {
   return stories;
 }

}

///////////////////////////////////////////////////////////////////////// import java.util.*; public class Story {

 private int id;
 private String info;
 private Group parent;
 
 public void setParent(Group g) {
   parent = g;
 }
 public Group getParent() {
   return parent;
 }
 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;
 }

}

/////////////////////////////////////////////////////////////////////////

<?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>
   
       <set name="stories" cascade="all" inverse="true">
            <key column="parent_id"/>
            <one-to-many class="Story"/>
       </set>
       <property name="name" type="string"/>
   </class>
   
   <class name="Story" table="story">
       <id name="id" unsaved-value="0">
            <generator class="increment"/>
       </id>
       <property name="info"/>
       <many-to-one name="parent" column="parent_id" not-null="true"/>
   </class>

</hibernate-mapping>

///////////////////////////////////////////////////////////////////////// <?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>
       
       <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>
       
       <property name="connection.pool_size">1</property>
       
       <property name="dialect">org.hibernate.dialect.HSQLDialect</property>
       
       <property name="show_sql">true</property>
       
       <mapping resource="Group.hbm.xml"/>
   </session-factory>

</hibernate-configuration>

///////////////////////////////////////////////////////////////////////// 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("       ");
   }
   }

}

      </source>
   
  
 
  



One To Many Mapping based on Array

   <source lang="java">

///////////////////////////////////////////////////////////////////////// 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");
    
     
     sp.setStories(new Story[]{new Story("Story Name 1"), new Story("Story Name 2")});
     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");      
  }

}

///////////////////////////////////////////////////////////////////////// <?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>
   
       <array name="stories" cascade="all">
            <key column="parent_id"/>
            <index column="idx"/>
            <one-to-many class="Story"/>
       </array>
       <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.util.*; public class Group {

 private int id;
 private String name;
 private Story[] 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(Story[] l) {
   stories = l;
 }
 public Story[] getStories() {
   return stories;
 }

}

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

}

///////////////////////////////////////////////////////////////////////// <?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>
       
       <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>
       
       <property name="connection.pool_size">1</property>
       
       <property name="dialect">org.hibernate.dialect.HSQLDialect</property>
       
       <property name="show_sql">true</property>
       
       <mapping resource="Group.hbm.xml"/>
   </session-factory>

</hibernate-configuration>

///////////////////////////////////////////////////////////////////////// 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("       ");
   }
   }

}

      </source>
   
  
 
  



One To Many Mapping based on Bag

   <source lang="java">

///////////////////////////////////////////////////////////////////////// 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");      
  }

}

///////////////////////////////////////////////////////////////////////// <?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>
         <bag name="stories" cascade="all">
                <key column="parent_id"/>
                <one-to-many class="Story"/>
         </bag>
         <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.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;
 }

}

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

}

///////////////////////////////////////////////////////////////////////// <?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>
       
       <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>
       
       <property name="connection.pool_size">1</property>
       
       <property name="dialect">org.hibernate.dialect.HSQLDialect</property>
       
       <property name="show_sql">true</property>
       
       <mapping resource="Group.hbm.xml"/>
   </session-factory>

</hibernate-configuration>

///////////////////////////////////////////////////////////////////////// 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("       ");
   }
   }

}


      </source>
   
  
 
  



One To Many Mapping based on Set

   <source lang="java">

///////////////////////////////////////////////////////////////////////// import java.util.*; import org.hibernate.*; import org.hibernate.criterion.*; public class SimpleRetrieveTest {


 public static void main(String[] args) {
   HibernateUtil.setup("create table EVENTS ( uid int, name VARCHAR, start_Date date, duration int, location_id int);");
   HibernateUtil.setup("create table speakers ( uid int, event_id int, firstName VARCHAR, lastName VARCHAR);");
   
   // hibernate code start
   Session session = HibernateUtil.currentSession();
   Transaction tx = session.beginTransaction();
       Event event = new Event();
       event.setName("One-to-many test");
       event.setSpeakers(new HashSet());
       event.getSpeakers().add(new Speaker("John", "Smith"));
       event.getSpeakers().add(new Speaker("Dave", "Smith"));
       event.getSpeakers().add(new Speaker("Joan", "Smith"));
       session.saveOrUpdate(event);
       tx.rumit();
   HibernateUtil.closeSession();
   HibernateUtil.sessionFactory.close();
       HibernateUtil.checkData("select * from speakers");
       HibernateUtil.checkData("select uid, name from events");        
   // hibernate code end
 }
 

}

///////////////////////////////////////////////////////////////////////// <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC

   "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
   "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>

   <class name="Event" table="events">
       <id name="id" column="uid" type="long" unsaved-value="null">
           <generator class="increment"/>
       </id>
       <property name="name" type="string" length="100"/>
       <property name="startDate" column="start_date"
                 type="date"/>
       <property name="duration" type="integer"/>
       <many-to-one name="location" column="location_id" class="Location"/>
       <set name="speakers" cascade="all">
           <key column="event_id"/>
           <one-to-many class="Speaker"/>
       </set>
       <set name="attendees" cascade="all">
           <key column="event_id"/>
           <one-to-many class="Attendee"/>
       </set>
   </class>

</hibernate-mapping>


///////////////////////////////////////////////////////////////////////// import java.util.Date; import java.util.Set; public class Event {

 private Long id;
 private String name;
 private Date startDate;
 private int duration;
 private Set speakers;
   private Set attendees;
   private Location location;
 public void setId(Long id) {
   this.id = id;
 }
 
 public Long getId() {
   return id;
 }
   public String getName() {
       return name;
   }
   public void setName(String name) {
       this.name = name;
   }
   public Date getStartDate() {
       return startDate;
   }
   public void setStartDate(Date startDate) {
       this.startDate = startDate;
   }
   public int getDuration() {
       return duration;
   }
   public void setDuration(int duration) {
       this.duration = duration;
   }
   public Location getLocation() {
       return location;
   }
   public void setLocation(Location location) {
       this.location = location;
   }
 public void setSpeakers(Set speakers) {
   this.speakers = speakers;
 }
 
 public Set getSpeakers() {
   return speakers;
 }
   public Set getAttendees() {
       return attendees;
   }
   public void setAttendees(Set attendees) {
       this.attendees = attendees;
   }

}


///////////////////////////////////////////////////////////////////////// <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC

   "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
   "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>

   <class name="Speaker" table="speakers">
       <id name="id" column="uid" type="long">
           <generator class="increment"/>
       </id>
       <property name="firstName" type="string" length="20"/>
       <property name="lastName" type="string" length="20"/>
   </class>

</hibernate-mapping>


///////////////////////////////////////////////////////////////////////// public class Speaker {

   private Long id;
   private String firstName;
   private String lastName;
   public Speaker() {
   }
   public Speaker(String firstName, String lastName) {
       setFirstName(firstName);
       setLastName(lastName);
   }
   public Long getId() {
       return id;
   }
   public void setId(Long id) {
       this.id = id;
   }
   public String getFirstName() {
       return firstName;
   }
   public void setFirstName(String firstName) {
       this.firstName = firstName;
   }
   public String getLastName() {
       return lastName;
   }
   public void setLastName(String lastName) {
       this.lastName = lastName;
   }

}

///////////////////////////////////////////////////////////////////////// <?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">org.hsqldb.jdbcDriver</property>
       <property name="connection.url">jdbc:hsqldb:data/tutorial</property>
       <property name="connection.username">sa</property>
       <property name="connection.password"></property>
       
       <property name="connection.pool_size">1</property>
       
       <property name="dialect">org.hibernate.dialect.HSQLDialect</property>
       
       <property name="show_sql">true</property>
       <mapping resource="Event.hbm.xml"/>
       <mapping resource="Speaker.hbm.xml"/>
       <mapping resource="Attendee.hbm.xml"/>
       <mapping resource="Location.hbm.xml"/>
   </session-factory>

</hibernate-configuration>

      </source>
   
  
 
  



One To Many Mapping List

   <source lang="java">

///////////////////////////////////////////////////////////////////////// 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");      
  }

}


///////////////////////////////////////////////////////////////////////// <?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.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;
 }

}

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

}

///////////////////////////////////////////////////////////////////////// <?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>
       
       <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>
       
       <property name="connection.pool_size">1</property>
       
       <property name="dialect">org.hibernate.dialect.HSQLDialect</property>
       
       <property name="show_sql">true</property>
       
       <mapping resource="Group.hbm.xml"/>
   </session-factory>

</hibernate-configuration>

      </source>