@Stateful
public class InvoiceBean implements Invoice {

    private int maxLineItems;

    private List<LineItem> items = new ArrayList<LineItem>();

    private int itemCount;

    /**
     * Injects the <b>maxLineItems</b> simple environment entry through bean
     * method.
     *
     * The JavaBeans property name (not the method name) is used as the default
     * JNDI name. By default, the JavaBeans propery name is combined with the
     * name of the class in which the annotation is used and is used directly as
     * the name in the bean's naming context. JNDI name for this entry would
     * be
     * java:comp/env/org.apache.openejb.examples.resource.InvoiceBean/maxLineItems
     *
     * Refer "EJB Core Contracts and Requirements" specification section 16.2.2.
     *
     * @param maxLineItems
     */
    @Resource
    public void setMaxLineItems(int maxLineItems) {
        this.maxLineItems = maxLineItems;
    }

    public void addLineItem(LineItem item) throws TooManyItemsException {
        if (item == null) {
            throw new IllegalArgumentException("Line item must not be null");
        }

        if (itemCount <= maxLineItems) {
            items.add(item);
            itemCount++;
        } else {
            throw new TooManyItemsException("Number of items exceeded the maximum limit");
        }
    }

    public int getMaxLineItems() {
        return this.maxLineItems;
    }

}

@Resource
private int maxLineItems;

<ejb-jar xmlns="http://java.sun.com/xml/ns/javaee" version="3.0" metadata-complete="false">
  <enterprise-beans>
    <session>
      <ejb-name>InvoiceBean</ejb-name>
      <env-entry>
        <description>The maximum number of line items per invoice.</description>
        <env-entry-name>org.superbiz.injection.InvoiceBean/maxLineItems</env-entry-name>
        <env-entry-type>java.lang.Integer</env-entry-type>
        <env-entry-value>15</env-entry-value>
      </env-entry>
    </session>
  </enterprise-beans>
</ejb-jar>

public class InvoiceBeanTest extends TestCase {

    private InitialContext initialContext;

    protected void setUp() throws Exception {
        Properties properties = new Properties();
        properties.setProperty(Context.INITIAL_CONTEXT_FACTORY, "org.apache.openejb.client.LocalInitialContextFactory");

        initialContext = new InitialContext(properties);
    }

    public void testAddLineItem() throws Exception {
        Invoice order = (Invoice) initialContext.lookup("InvoiceBeanRemote");
        assertNotNull(order);
        LineItem item = new LineItem("ABC-1", "Test Item");

        try {
            order.addLineItem(item);
        } catch (TooManyItemsException tmie) {
            fail("Test failed due to: " + tmie.getMessage());
        }
    }

    public void testGetMaxLineItems() throws Exception {
        Invoice order = (Invoice) initialContext.lookup("InvoiceBeanRemote");
        assertNotNull(order);

        int maxLineItems = order.getMaxLineItems();

        assertEquals(15, maxLineItems);
    }
}