Access to persistence context from AbstractResource or Servlet

13. Aug 2008, 15:13 CET | Link Marcos LoisBermudez

Hello i have some problems getting org.jboss.seam.web.AbstractResource to work, i also try to use a pure servlet to stream data to client with the same problem.

If i stream data from filesystem no problem with both aproaches, but when i try to stream data that is stored in database (I access data trought Hibernate JPA implementation), i can't get a entity manager, i can only solve this on pure Servlet getting a EnityManagerFactory from JNDI.

So is posible to inject the persistenceContext in AbstractResource instance or pure Servlet? I try out most of the examples and nothing work.

This is my code, running on JBoss 4.2.2GA:

components.xml

<persistence:managed-persistence-context name="entityManager" auto-create="true" persistence-unit-jndi-name="java:/axudasEntityManagerFactory" />

persistence.xml

<persistence-unit name="axudas">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    <jta-data-source>java:/axudasDatasource</jta-data-source>
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.Oracle9Dialect"/>
      <property name="hibernate.hbm2ddl.auto" value="validate"/>
      <property name="hibernate.show_sql" value="true"/>
      <property name="hibernate.format_sql" value="true"/>
      <property name="jboss.entity.manager.factory.jndi.name" value="java:/axudasEntityManagerFactory"/>
    </properties>
</persistence-unit>

MediaServlet.java

public class MediaServlet extends javax.servlet.http.HttpServlet implements
        javax.servlet.Servlet {
    static final long serialVersionUID = 1L;

    /*
     * (non-Java-doc)
     *
     * @see javax.servlet.http.HttpServlet#HttpServlet()
     */
    public MediaServlet() {
        super();
    }

    /*
     * (non-Java-doc)
     *
     * @see javax.servlet.http.HttpServlet#doGet(HttpServletRequest request,
     *      HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("application/octet-stream");
        response.addHeader("Content-disposition",
                "attachment; filename=\"image.jpg\"");
        response.addHeader("Cache-Control", "no-cache");
        response.setStatus(200);
       
        // perform JNDI lookup to obtain container-managed entity manager
        EntityManager entityManager;
       
        Context initCtx;
        try {
            initCtx = new InitialContext();
            entityManager = ((EntityManagerFactory) initCtx
                    .lookup("java:axudasEntityManagerFactory")).createEntityManager();
        } catch (NamingException e) {
            throw new ServletException(e);
        }

        Prueba pb = entityManager.find(Prueba.class, 10848);

        response.flushBuffer();
        ServletOutputStream out = response.getOutputStream();

        InputStream in;
        try {
            in = pb.getData().getBinaryStream();
        } catch (SQLException e) {
            throw new ServletException(e);
        }
        // FileInputStream in = new FileInputStream(new
        // File("C:/Marcos/SIVSA/Download/eclipse-cpp-ganymede-win32.zip"));
        byte[] buff = new byte[1024];
        int nread = 0;

        while ((nread = in.read(buff)) > 0) {
            out.write(buff, 0, nread);
            out.flush();
            response.flushBuffer();
        }

        out.close();
        in.close();
    }
}

MediaResource.java

@Scope(ScopeType.APPLICATION)
@Name("myResource")
@BypassInterceptors
public class Resource extends AbstractResource {
   
    @In
    private EntityManagerFactory entityManagerFactory;

    @Override
    public String getResourcePath() {
        return "/myresource";
    }


    @Override
    public void getResource(final HttpServletRequest request, final HttpServletResponse response)
            throws ServletException, IOException {

        new ContextualHttpServletRequest(request) {
            @Override
            public void process() throws IOException, ServletException {
                response.setContentType("application/octet-stream");
                response.addHeader("Content-disposition", "attachment; filename=\"image.jpg\"");
                response.addHeader("Cache-Control", "no-cache");
                response.setStatus(200);
               
                response.flushBuffer();
                ServletOutputStream out = response.getOutputStream();
               
                EntityManager entityManager = entityManagerFactory.createEntityManager();
               
                Prueba pb = entityManager.find(Prueba.class, 10848);
               
                InputStream in;
                try {
                    in = pb.getData().getBinaryStream();
                } catch (SQLException e) {
                    throw new ServletException(e);
                }
//                FileInputStream in = new FileInputStream(new File("C:/Marcos/SIVSA/Download/eclipse-cpp-ganymede-win32.zip"));
                byte[] buff = new byte[1024];
                int nread = 0;
               
                while((nread = in.read(buff)) > 0) {
                    out.write(buff, 0, nread);
                    out.flush();
                    response.flushBuffer();
                }
               
                out.close();
                in.close();
            }
        }.run();
    }
}

So how inyect the persistence context in a clean way to AbstractResource or Servlet?

Marcos Lois