Hibernate with Scala example in one file

[Steve Yen]

Just worked through Hibernate's tutorial, but using Scala. Googling for hints turned up info from Matt Hellige's blog(s) and Viktor Klang from the lift web group. So with a tip of the hat to them, here's a working example of using Hibernate from Scala, in a single file. Enjoy...

package scalanate
import scala.xml._ import java.util.Date import org.hibernate._ import org.hibernate.cfg._  class Event {   var id: Long = 0L    var title: String = null   var date: Date = null    var participants: java.util.Set = new java.util.HashSet      override def toString = "Event " + id + " " + title + " " + date }  class Person {   var id: Long = 0L    var age: Int = 0   var name: String = null     var events: java.util.Set = new java.util.HashSet    override def toString = "Person " + id + " " + name + " " + age }  object Main {    def main(args: Array[String]) {     println("main: " + args.mkString(","));          args(0) match {       case "test0" => test0       case "test1" => test1       case "test2" => test2     }   }    def test0 =      withTxSession(session => {       val e1 = new Event       e1.title = "hi"       e1.date = new Date       session.save(e1)     })        def test1 = {     withTxSession(session => {       val e1 = new Event       e1.title = "hi"       e1.date = new Date       session.save(e1)       val e2 = new Event       e2.title = "bye"       e2.date = new Date       session.save(e2)       val eIter = session.createQuery("from Event").list.iterator       while (eIter.hasNext) {         val e = eIter.next.asInstanceOf[Event]         println(e)       }     })   }      def test2 = {     withTxSession(session => {       val e1 = new Event       e1.title = "hi"       e1.date = new Date       session.save(e1)       val e2 = new Event       e2.title = "bye"       e2.date = new Date       session.save(e2)       val p1 = new Person       p1.name = "p1"       p1.age = 21       session.save(p1)     })          println("test2.a")      withTxSession(session => {       val p1 = session.createQuery("from Person").list.get(0).asInstanceOf[Person]       println(p1)              val eIter = session.createQuery("from Event").list.iterator       while (eIter.hasNext) {         val e = eIter.next.asInstanceOf[Event]         p1.events.add(e)         e.participants.add(p1)       }     })      println("test2.b")      withTxSession(session => {       val p1 = session.createQuery("from Person").list.get(0).asInstanceOf[Person]       println(p1)       println(p1.events)       val eIter = p1.events.iterator       while (eIter.hasNext) {         val e = eIter.next.asInstanceOf[Event]         println(e)         println(e.participants)       }     })      println("test2.c")   }      def withTxSession(f: (Session) => Any) = {     val s = sessionFactory.getCurrentSession     val t = s.beginTransaction     val r = f(s)     t.commit     r   }    // ---------------------------------    lazy val sessionFactory = configuration.buildSessionFactory   lazy val configuration  = (new Configuration).configure(configDoc).addDocument(mappingDoc)      // ---------------------------------    def mappingDoc = parseDoc(mappingXML)   def mappingXML =      <hibernate-mapping default-access="field">       <class name="scalanate.Event" table="EVENTS">           <id name="id" column="EVENT_ID">               <generator class="native"/>           </id>           <property name="date" type="timestamp" column="EVENT_DATE"/>           <property name="title"/>           <set name="participants" table="PERSON_EVENT" inverse="true">               <key column="EVENT_ID"/>               <many-to-many column="PERSON_ID" class="scalanate.Person"/>           </set>       </class>       <class name="scalanate.Person" table="PERSON">           <id name="id" column="PERSON_ID">               <generator class="native"/>           </id>           <property name="age"/>           <property name="name"/>           <set name="events" table="PERSON_EVENT">               <key column="PERSON_ID"/>               <many-to-many column="EVENT_ID" class="scalanate.Event"/>           </set>                 </class>     </hibernate-mapping>            def configDoc = parseDoc(configXML)   def configXML =     <hibernate-configuration>             <session-factory>             <!-- Database connection settings -->             <property name="connection.driver_class">org.h2.Driver</property>             <property name="connection.url">jdbc:h2:mem:test_mem</property>             <property name="connection.username">admin</property>             <property name="connection.password"></property>                 <property name="dialect">org.hibernate.dialect.H2Dialect</property>              <property name="current_session_context_class">thread</property>              <!-- Emit generated sql for debugging -->             <property name="show_sql">true</property>              <!-- Auto-drop/recreate schema on startup -->             <property name="hbm2ddl.auto">create</property>          </session-factory>         </hibernate-configuration>          // ---------------------------------    lazy val parseDocFactory = javax.xml.parsers.DocumentBuilderFactory.newInstance    def parseDoc(x: Node) = {     import org.xml.sax.InputSource     import java.io.StringReader      parseDocFactory.newDocumentBuilder.parse(new InputSource(new StringReader(x.toString)))   } }

A large chunk of the code is just the test1/2/3 methods which exercise the Hibernate API, per the tutorial. And, you can see I couldn't resist using Scala's inline XML feature.

(Scala experts: if anyone has a better way of turning a Scala Node/Elem into a real org.w3c.dom.Document so I can pass it into Hibernate, I would love to know how!)

If you save the above as test.scala, then you can compile and run it with

scalac test.scala
java scalanate.Main [test0|test1|test2] 

By the way, I had to add all these jars to my classpath to get it to work. Sheesh.

set CLASSPATH=%CLASSPATH%;lib\scala-library.jar
set CLASSPATH=%CLASSPATH%;lib\antlr-2.7.6.jar set CLASSPATH=%CLASSPATH%;lib\antlr-2.7.6.jar set CLASSPATH=%CLASSPATH%;lib\asm.jar set CLASSPATH=%CLASSPATH%;lib\asm-attrs.jar set CLASSPATH=%CLASSPATH%;lib\cglib-2.1.3.jar set CLASSPATH=%CLASSPATH%;lib\commons-collections-2.1.1.jar set CLASSPATH=%CLASSPATH%;lib\commons-logging-1.0.4.jar set CLASSPATH=%CLASSPATH%;lib\dom4j-1.6.1.jar set CLASSPATH=%CLASSPATH%;lib\jaxen-1.1-beta-7.jar set CLASSPATH=%CLASSPATH%;lib\log4j-1.2.11.jar set CLASSPATH=%CLASSPATH%;lib\jta.jar set CLASSPATH=%CLASSPATH%;lib\h2.jar set CLASSPATH=%CLASSPATH%;lib\hibernate3.jar