Hibernate example source code file (tutorial_jpa.xml)

This example Hibernate source code file (tutorial_jpa.xml) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

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The Hibernate tutorial_jpa.xml source code

<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">

<chapter id="hibernate-gsg-tutorial-jpa">
    <title>Tutorial Using the Java Persistence API (JPA)

    <para>
      This tutorial is located within the download bundle under <filename>entitymanager.
    </para>
    <itemizedlist>
      <title>Objectives
      <listitem>
        <para>
          Use annotations to provide mapping information.
        </para>
      </listitem>
      <listitem>
        <para>
          Use <systemitem>JPA.
        </para>
      </listitem>
    </itemizedlist>

    <section id="hibernate-gsg-tutorial-jpa-config">
        <title>persistence.xml

        <para>
            The previous tutorials used the Hibernate-specific
            <filename>hibernate.cfg.xml configuration file.
            <systemitem>JPA, however, defines a different bootstrap process that uses its own configuration
            file named <filename>persistence.xml.  This bootstrapping process is defined by the
            <systemitem>JPA specification.  In Java SE environments the persistence
            provider (Hibernate in this case) is required to locate all <systemitem>JPA configuration files
            by classpath lookup of the <filename>META-INF/persistence.xml resource name.
        </para>

        <example id="hibernate-gsg-tutorial-jpa-config-pu">
          <title>persistence.xml
          <programlisting role="XML">
        </example>

        <para>
          <filename>persistence.xml files should provide a unique name for each persistence
          unit</phrase>.  Applications use this name to reference the configuration when obtaining an
          <interfacename>javax.persistence.EntityManagerFactory reference.
        </para>

        <para>
          The settings defined in the <varname>properties element are discussed in javax.persistence-prefixed
          varieties are used when possible.  Notice that the remaining Hibernate-specific configuration setting names
          are now prefixed with <literal>hibernate..
        </para>

        <para>
          Additionally, the <varname>class element functions the same as in 
        <para>
          The entity is exactly the same as in <xref linkend="hibernate-gsg-tutorial-annotations-entity"/>
        </para>
    </section>

    <section id="hibernate-gsg-tutorial-jpa-test">
        <title>Example code
        <para>
          The previous tutorials used the Hibernate APIs.  This tutorial uses the <systemitem>JPA APIs.
        </para>

        <example id="hibernate-gsg-tutorial-jpa-test-setUp">
          <title>Obtaining the javax.persistence.EntityManagerFactory
          <programlisting role="JAVA">protected void setUp() throws Exception {
    entityManagerFactory = Persistence.createEntityManagerFactory( "org.hibernate.tutorial.jpa" );
}</programlisting>
        </example>

        <para>
          Notice again that the persistence unit name is <literal>org.hibernate.tutorial.jpa, which matches
          <xref linkend="hibernate-gsg-tutorial-jpa-config-pu"/>
        </para>

        <example id="hibernate-gsg-tutorial-jpa-test-saving">
          <title>Saving (persisting) entities
          <programlisting role="JAVA">EntityManager entityManager = entityManagerFactory.createEntityManager();
entityManager.getTransaction().begin();
entityManager.persist( new Event( "Our very first event!", new Date() ) );
entityManager.persist( new Event( "A follow up event", new Date() ) );
entityManager.getTransaction().commit();
entityManager.close();</programlisting>
        </example>

        <para>
          The code is similar to <xref linkend="hibernate-gsg-tutorial-basic-test-saving"/>.  An
          <interfacename>javax.persistence.EntityManager interface is used instead of a
          <interfacename>org.hibernate.Session interface.  JPA calls this
          operation <methodname>persist instead of save.
        </para>

        <example id="hibernate-gsg-tutorial-jpa-test-list">
          <title>Obtaining a list of entities
          <programlisting role="JAVA">
        </example>

        <para>
          Again, the code is pretty similar to <xref linkend="hibernate-gsg-tutorial-basic-test-list"/>.
        </para>
    </section>

    <section id="hibernate-gsg-tutorial-annotations-further">
        <title>Take it further!
        <itemizedlist>
            <title>Practice Exercises
            <listitem>
                <para>
                    Develop an EJB Session bean to investigate implications of using a container-managed
                    persistence context (<interfacename>javax.persistence.EntityManager).  Try both
                    stateless and stateful use-cases.
                </para>
            </listitem>
        </itemizedlist>
    </section>
</chapter>