Using OpenEJB for Unit Testing with Hibernate in NetBeans IDE

by Wesley Liu

EJB3 has simplified EJB development a lot. However, it has imposed new difficulties on out-of-container testing with the use of dependency injection. OpenEJB provides a way of doing EJB testing within the J2SE environment in a lightweight container.

I am using Hibernate as the JPA implementation in current development, and I would like to demonstrate how to test EJBs in Netbeans 6.1 using OpenEJB.

Here's How to Do It

1. Download OpenEJB from, the current version is 3.1. Unzip the file, you'll find all the required jar files under {somewhere to put the unzipped files}:

2. In NetBeans IDE, under Tools --> Library --> new Library, create a library called openejb.


3. Assume that you have an existing EJB project with a test Stateless Session Bean as following:

public class MyTestBean implements MyTestLocal {

public String sayHello() {

return "haha";


Here's the persistence configuration:

<persistence-unit name="my-ejbPU" transaction-type="JTA">

4. Add ejb-jar.xml into configuration files of the EJB project as the follows:

The above declaration is used for telling the OpenEJB container to scan the jar file containing the EJBs and deploy it along with any annotated beans it may contain. 

5. Create a J2SE project named testapp. Add the openejb and the EJB project as Library. If you use MySQL as the database, please add the mysql connectorJ library as well.

6. Create a unit test in the J2SE project.

public class NewJUnitTest extends TestCase {

private InitialContext initialContext;

public NewJUnitTest() {

public static void setUpClass() throws Exception {

public static void tearDownClass() throws Exception {

public void setUp() {

//Init the OpenEJB Container
try {
Properties p = new Properties();
p.setProperty(Context.INITIAL_CONTEXT_FACTORY, "org.apache.openejb.client.LocalInitialContextFactory");
//Config the DataSource with MySQL
p.put("myds", "new://Resource?type=DataSource");
p.put("myds.JdbcDriver", "com.mysql.jdbc.Driver");
p.put("myds.JdbcUrl", "jdbc:mysql://localhost:3306/mydb");
p.setProperty("myds.UserName", "test");
p.setProperty("myds.Password", "test");

//It's specially for MySQL where hibernate.dialect must be explicitly set
p.put("my-ejbPU.hibernate.dialect", "org.hibernate.dialect.MySQLInnoDBDialect");

initialContext = new InitialContext(p);
} catch (NamingException ex) {


//Here's the testing Code
public void testSayHello(){
try {

Object object = initialContext.lookup("MyTestBeanLocal");
assertTrue(object instanceof MyTestLocal);
MyTestLocal mt = (MyTestLocal) object;

} catch (NamingException ex) {

public void tearDown() {


Final Note

After all, you can test any Entity or SessionBeans in a J2SE environment. When you start the OpenEJB container in SetUp(), the Persistence Provider Implementation will check the entity mappings with the database. DBUnit could also be introduced if you would like to test Entity Beans.

Some questions

Thx for the post. I tried open ejb and got the examples on their webpage running, using maven. However when I tried to create a small EJB Project, similar to yours - but w/o db access, I didn't get it running..

The example is very minimal, contains an EJB with one method and a jUnit test, which loads openejb with and then gets the object as above when testing the method.

        Properties properties = new Properties();

        initialContext = new InitialContext(properties);

Here is the error I get:

INFO - Beginning load: /Users/nils/JavaLibs/openejb-3.1.1/lib/xml-resolver-1.2.jar
INFO - Configuring enterprise application: classpath.ear
WARN - No application-client.xml found assuming annotations present: classpath.ear, module: ant.jar
WARN - No application-client.xml found assuming annotations present: classpath.ear, module: ant-launcher.jar
WARN - No application-client.xml found assuming annotations present: classpath.ear, module: webservices-tools.jar
WARN - No application-client.xml found assuming annotations present: classpath.ear, module: xml-resolver-1.2.jar
java.lang.Exception: Could not load 1/0/com/sun/codemodel/CodeWriter.class

To me it's also not clear what acctually happens. When creating the initial context, openejb is somehow loaded, which then finds (how?) and loads the concerning EJB class. Thx for your response :)

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