{"id":1451,"date":"2012-07-17T18:08:40","date_gmt":"2012-07-17T16:08:40","guid":{"rendered":"http:\/\/www.tutego.de\/blog\/javainsel\/?p=1451"},"modified":"2012-07-17T18:08:40","modified_gmt":"2012-07-17T16:08:40","slug":"jpa-beispiel-in-wenigen-minuten-mit-openjpa","status":"publish","type":"post","link":"https:\/\/www.tutego.de\/blog\/javainsel\/2012\/07\/jpa-beispiel-in-wenigen-minuten-mit-openjpa\/","title":{"rendered":"JPA-Beispiel in wenigen Minuten mit OpenJPA"},"content":{"rendered":"
    \n
  1. Beziehe unter http:\/\/mvnrepository.com\/artifact\/org.apache.openjpa\/openjpa-all<\/a> das openjpa-all-2.2.0.jar<\/em> (etwas mehr als 6 MiB) und setzte es in den Klassenpfad.<\/li>\n
  2. Habe einen Datentreiber im Klassenpfad (bei mir den der HSQLDB).<\/li>\n
  3. Lege im Projekt einen Ordner META-INF<\/em> an, platziere dort eine Datei persistence.xml:<\/em><\/li>\n

    <?xml version="1.0" encoding="UTF-8"?>
    <persistence xmlns="    http:\/\/java.sun.com\/xml\/ns\/persistence"<\/a>
      xmlns:xsi="    http:\/\/www.w3.org\/2001\/XMLSchema-instance"<\/a>
      xsi:schemaLocation="    http:\/\/java.sun.com\/xml\/ns\/persistence<\/a> persistence_2_0.xsd"
      version="2.0">
      <persistence-unit name="traida" transaction-type="RESOURCE_LOCAL">
        <class>traida.shared.domain.Contact<\/class>
        <properties>
          <property name="openjpa.jdbc.DBDictionary" value="hsql"\/>
          <property name="javax.persistence.jdbc.url" value="jdbc:hsqldb:file:hsqldbtest;user=sa" \/>
          <property name="javax.persistence.jdbc.driver" value="org.hsqldb.jdbcDriver" \/>
          <property name="openjpa.Log" value="DefaultLevel=ERROR, Tool=ERROR" \/>
          <property name="openjpa.jdbc.SynchronizeMappings" value="buildSchema(ForeignKeys=true)"\/>
        <\/properties>
      <\/persistence-unit>
    <\/persistence><\/p>\n

    Mehr zu den Properties unter http:\/\/openjpa.apache.org\/builds\/apache-openjpa-2.2.1-SNAPSHOT\/docs\/docbook\/manual\/main.html<\/a>.<\/p>\n

  4. Lege eine Klasse traida.shared.domain.Contact an:<\/li>\n

    @Entity
    public class Contact {
      @Id
      @GeneratedValue( strategy = GenerationType.IDENTITY )
      public Long id;
      public String name;
      \/\/ Setter\/Getter ausgelassen
    }<\/p>\n

  5. Schreibe eine main(String[])-Methode mit:<\/li>\n

    EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory( "traida" );
    EntityManager entityManager = entityManagerFactory.createEntityManager();
    entityManager.getTransaction().begin();
    Contact c = new Contact();
    c.name = "Hallo Willi";
    entityManager.persist( c );
    entityManager.getTransaction().commit();
    System.out.println( entityManager.createQuery( "select c from Contact c" ).getResultList() );
    entityManager.close();<\/p>\n

  6. Fertig, jetzt freuen.<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"

    Beziehe unter http:\/\/mvnrepository.com\/artifact\/org.apache.openjpa\/openjpa-all das openjpa-all-2.2.0.jar (etwas mehr als 6 MiB) und setzte es in den Klassenpfad. Habe einen Datentreiber im Klassenpfad (bei mir den der HSQLDB). Lege im Projekt einen Ordner META-INF an, platziere dort eine Datei persistence.xml: <?xml version="1.0" encoding="UTF-8"?> <persistence xmlns="http:\/\/java.sun.com\/xml\/ns\/persistence"   xmlns:xsi="http:\/\/www.w3.org\/2001\/XMLSchema-instance"   xsi:schemaLocation="http:\/\/java.sun.com\/xml\/ns\/persistence persistence_2_0.xsd"   version="2.0">   <persistence-unit name="traida" transaction-type="RESOURCE_LOCAL">     […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[9],"tags":[72,73,74],"class_list":["post-1451","post","type-post","status-publish","format-standard","hentry","category-java-ee","tag-ejb","tag-jpa","tag-openjpa"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/posts\/1451","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/comments?post=1451"}],"version-history":[{"count":1,"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/posts\/1451\/revisions"}],"predecessor-version":[{"id":1452,"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/posts\/1451\/revisions\/1452"}],"wp:attachment":[{"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/media?parent=1451"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/categories?post=1451"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/tags?post=1451"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}