= Tomcat JPA
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:jbake-status: published

Tomcat + Java EE = TomEE, the Java Enterprise Edition of Tomcat.
With TomEE you get Tomcat with JPA added and integrated and ready to go!

In a plain Servlet, Filter or Listener you can do fun things like injection of JPA EntityManager or EntityManagerFactory:

....
import javax.annotation.Resource;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.servlet.http.HttpServlet;
import javax.transaction.UserTransaction;

public class MyServet extends HttpServlet {

    @Resource
    private UserTransaction userTransaction;

    @PersistenceContext
    private EntityManager entityManager;


    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //...

        userTransaction.begin();

        try {
            entityManager.persist(new Movie("Quentin Tarantino", "Reservoir Dogs", 1992));
            entityManager.persist(new Movie("Joel Coen", "Fargo", 1996));
            entityManager.persist(new Movie("Joel Coen", "The Big Lebowski", 1998));
        } finally {
            userTransaction.commit();
        }

        //...
    }

}
....

No need to add even a single library!
To make the above work all you need is a `WEB-INF/persistence.xml` file in your webapp like the following:

....
<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0">

  <persistence-unit name="movie-unit">
    <jta-data-source>movieDatabase</jta-data-source>
    <non-jta-data-source>movieDatabaseUnmanaged</non-jta-data-source>

    <properties>
      <property name="openjpa.jdbc.SynchronizeMappings" value="buildSchema(ForeignKeys=true)"/>
    </properties>
  </persistence-unit>
</persistence>
....

DataSources will automatically be created if they haven't be configured explicitly.

xref:download-ng.adoc[Download] TomEE and you're minutes away from a functioning JPA application on Tomcat.

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