Java/Hibernate/Relation Many to Many

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Collection Mapping: Many-To-Many map based on HashMap

   <source lang="java">

///////////////////////////////////////////////////////////////////////// public class Benefit { 

 private int id;
 private int cost;
 public Benefit() {
 }
 public Benefit(int c) {
   cost = c;
 }
 public void setId(int i) {
   id = i;
 }
 public int getId() {
   return id;
 }
 public void setCost(int i) {
   cost = i;
 }
 public int getCost() {
   return cost;
 }

} ///////////////////////////////////////////////////////////////////////// <?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="Employee" table="employee">
       <id name="id" unsaved-value="0">
           <generator class="increment"/>
       </id>
       
       <map name="benefits" table="employee_benefit" cascade="all">
           <key column="parent_id"/>
           <index column="benefit_name" type="string"/>
           <many-to-many column="benefit_id" class="Benefit"/>
       </map>
       <property name="name" type="string"/>
   </class>
   <class name="Benefit" table="benefit">
       <id name="id" unsaved-value="0">
           <generator class="increment"/>
       </id>
       <property name="cost" type="int"/>
   </class>

</hibernate-mapping>

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

import java.util.*; public class Employee { 

 private int id;
 private String name;
 private Map benefits;
 public Employee() {
 }
 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 setBenefits(Map m) {
   benefits = m;
 }
 
 public Map getBenefits() {
   return benefits;
 }

} /////////////////////////////////////////////////////////////////////////

<?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="Employee.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("       ");
   }
   }

}

///////////////////////////////////////////////////////////////////////// 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 employee (id int,name varchar);");    
     HibernateUtil.setup("create table benefit (id int,cost int);");    
     HibernateUtil.setup("create table employee_benefit (parent_id int,benefit_name varchar,benefit_id int);");    

     Session session = HibernateUtil.currentSession();
     Employee sp = new Employee();
     Employee sp3 = new Employee();
    
     sp.setName("Joe");
     HashMap p = new HashMap();
     p.put("health", new Benefit(200));
     p.put("dental", new Benefit(300));
     sp.setBenefits(p);
     sp3.setName("Jim");
     sp3.setBenefits(p);
     session.save(sp);
     session.save(sp3);
     session.flush();
     HibernateUtil.closeSession();
     session = HibernateUtil.currentSession();
     Employee sp2 = (Employee)session.load(Employee.class, new Integer(sp.getId()));
     Map p2 = sp2.getBenefits();
     System.out.println(((Benefit)p2.get("health")).getCost());
     System.out.println(((Benefit)p2.get("dental")).getCost());

     session.flush();
     session.close();
     HibernateUtil.checkData("select * from employee");
     HibernateUtil.checkData("select * from benefit");
     HibernateUtil.checkData("select * from employee_benefit");
  }

} 


      </source>



Many To Many Map Cascade Load

   <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 m_EVENTS ( uid int, name VARCHAR, start_Date date, duration int, location_id int);");
   HibernateUtil.setup("create table m_speakers ( uid int, firstName VARCHAR, lastName VARCHAR);");
   HibernateUtil.setup("create table event_speakers (elt int, event_id int, speaker_id int);");
   
   // hibernate code start
   Session session = HibernateUtil.currentSession();
   Transaction tx = session.beginTransaction();

       EventManyToMany event = new EventManyToMany();
       event.setName("Inverse test");
       event.setSpeakers(new HashSet());
       event.getSpeakers().add(new SpeakerManyToMany("John", "Smith", event));
       event.getSpeakers().add(new SpeakerManyToMany("Dave", "Smith", event));
       event.getSpeakers().add(new SpeakerManyToMany("Joan", "Smith", event));

       session.save(event);

       event = (EventManyToMany) session.load(EventManyToMany.class, event.getId());
       Set speakers = event.getSpeakers();
       for (Iterator i = speakers.iterator(); i.hasNext();) {
           SpeakerManyToMany speaker = (SpeakerManyToMany) i.next();
           System.out.println(speaker.getFirstName());
           System.out.println(speaker.getLastName());
           System.out.println(speaker.getId());
       }

       tx.rumit();
   HibernateUtil.closeSession();
   HibernateUtil.sessionFactory.close();
       HibernateUtil.checkData("select * from m_speakers");
       HibernateUtil.checkData("select uid, name from m_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="SpeakerManyToMany" table="m_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"/>
       <set name="events" table="event_speakers" cascade="all">
           <key column="speaker_id"/>
           <many-to-many class="EventManyToMany"/>
       </set>
   </class>

</hibernate-mapping>

///////////////////////////////////////////////////////////////////////// import java.util.Set; import java.util.HashSet; public class SpeakerManyToMany { 

   private Long id;
   private String firstName;
   private String lastName;
   private Set events;
   public SpeakerManyToMany() {
   }
   public SpeakerManyToMany(String firstName, String lastName) {
       setFirstName(firstName);
       setLastName(lastName);
   }
   public SpeakerManyToMany(String firstName, String lastName, EventManyToMany event) {
       this(firstName, lastName);
       addEvent(event);
   }
   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;
   }
   public Set getEvents() {
       return this.events;
   }
   public void setEvents(Set events) {
       this.events = events;
   }
   private void addEvent(EventManyToMany event) {
       if (events == null) {
           events = new HashSet();
       }
       events.add(event);
   }

}

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

 private Long id;
 private String name;
 private Date startDate;
 private int duration;
 private Set speakers;
   private Set attendees;
   private LocationManyToMany 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 LocationManyToMany getLocation() {
       return location;
   }
   public void setLocation(LocationManyToMany 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="EventManyToMany" table="m_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="LocationManyToMany"/>
       <set name="speakers" table="event_speakers" cascade="all">
           <key column="event_id"/>
           <many-to-many class="SpeakerManyToMany"/>
       </set>
   </class>

</hibernate-mapping>

///////////////////////////////////////////////////////////////////////// <?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="EventManyToMany.hbm.xml"/>
       <mapping resource="SpeakerManyToMany.hbm.xml"/>
       <mapping resource="LocationManyToMany.hbm.xml"/>
   </session-factory>

</hibernate-configuration> 

      </source>



Many to Many Map Cascade Save

   <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 m_EVENTS ( uid int, name VARCHAR, start_Date date, duration int, location_id int);");
   HibernateUtil.setup("create table m_speakers ( uid int, firstName VARCHAR, lastName VARCHAR);");
   HibernateUtil.setup("create table event_speakers (elt int, event_id int, speaker_id int);");
   
   // hibernate code start
   Session session = HibernateUtil.currentSession();
   Transaction tx = session.beginTransaction();

       EventManyToMany event = new EventManyToMany();
       event.setName("Inverse test");
       event.setSpeakers(new HashSet());
       event.getSpeakers().add(new SpeakerManyToMany("John", "Smith", event));
       event.getSpeakers().add(new SpeakerManyToMany("Dave", "Smith", event));
       event.getSpeakers().add(new SpeakerManyToMany("Joan", "Smith", event));

       session.save(event);

       tx.rumit();
   HibernateUtil.closeSession();
   HibernateUtil.sessionFactory.close();
       HibernateUtil.checkData("select * from m_speakers");
       HibernateUtil.checkData("select uid, name from m_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="EventManyToMany" table="m_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="LocationManyToMany"/>
       <set name="speakers" table="event_speakers" cascade="all">
           <key column="event_id"/>
           <many-to-many class="SpeakerManyToMany"/>
       </set>
   </class>

</hibernate-mapping>


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

 private Long id;
 private String name;
 private Date startDate;
 private int duration;
 private Set speakers;
   private Set attendees;
   private LocationManyToMany 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 LocationManyToMany getLocation() {
       return location;
   }
   public void setLocation(LocationManyToMany 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="SpeakerManyToMany" table="m_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"/>
       <set name="events" table="event_speakers" cascade="all">
           <key column="speaker_id"/>
           <many-to-many class="EventManyToMany"/>
       </set>
   </class>

</hibernate-mapping>


///////////////////////////////////////////////////////////////////////// import java.util.Set; import java.util.HashSet; public class SpeakerManyToMany { 

   private Long id;
   private String firstName;
   private String lastName;
   private Set events;
   public SpeakerManyToMany() {
   }
   public SpeakerManyToMany(String firstName, String lastName) {
       setFirstName(firstName);
       setLastName(lastName);
   }
   public SpeakerManyToMany(String firstName, String lastName, EventManyToMany event) {
       this(firstName, lastName);
       addEvent(event);
   }
   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;
   }
   public Set getEvents() {
       return this.events;
   }
   public void setEvents(Set events) {
       this.events = events;
   }
   private void addEvent(EventManyToMany event) {
       if (events == null) {
           events = new HashSet();
       }
       events.add(event);
   }

}

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

      </source>
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