Title: CDI @Inject
To use @Inject
, the first thing you need is a META-INF/beans.xml
file in the module or jar. This effectively turns on CDI and allows the @Inject
references to work. No META-INF/beans.xml
no injection, period. This may seem overly strict, but it is not without reason. The CDI API is a bit greedy and does consume a fair about of resources by design.
When the container constructs a bean with an @Inject
reference, it will first find or create the object that will be injected. For the sake of simplicity, the is example has a basic Faculty
pojo with a no-arg constructor. Anyone referencing @Inject Faculty
will get their own instance of Faculty
. If the desire is to share the same instance of Faculty
, see the concept of scopes
-- this is exactly what scopes are for.
In this example we have an @Stateless
bean Course
with an @Inject
reference to an object of type Faculty
. When Course
is created, the container will also create an instance of Faculty
. The @PostConstruct
will be called on the Faculty
, then the Faculty
instance will be injected into the Course
bean. Finally, the @PostConstruct
will be invoked on Course
and then we're done. All instances will have been created.
The CourseTest
test case drives this creation process by having Course
injected into it in its @Setup
method. By the time our @Test
method is invoked, all the real work should be done and we should be ready to go. In the test case we do some basic asserts to ensure everything was constructed, all @PostConstruct
methods called and everyting injected.
public class Faculty { private List<String> facultyMembers; private String facultyName; @PostConstruct public void initialize() { this.facultyMembers = new ArrayList<String>(); facultyMembers.add("Ian Schultz"); facultyMembers.add("Diane Reyes"); facultyName = "Computer Science"; } public List<String> getFacultyMembers() { return facultyMembers; } public String getFacultyName() { return facultyName; } }
@Stateless public class Course { @Inject private Faculty faculty; private String courseName; private int capacity; @PostConstruct private void init() { assert faculty != null; // These strings can be externalized // We'll see how to do that later this.courseName = "CDI 101 - Introduction to CDI"; this.capacity = 100; } public String getCourseName() { return courseName; } public int getCapacity() { return capacity; } public Faculty getFaculty() { return faculty; } }
public class CourseTest extends TestCase { @EJB private Course course; @Before public void setUp() throws Exception { EJBContainer.createEJBContainer().getContext().bind("inject", this); } @Test public void test() { // Was the EJB injected? assertTrue(course != null); // Was the Course @PostConstruct called? assertNotNull(course.getCourseName()); assertTrue(course.getCapacity() > 0); // Was a Faculty instance injected into Course? final Faculty faculty = course.getFaculty(); assertTrue(faculty != null); // Was the @PostConstruct called on Faculty? assertEquals(faculty.getFacultyName(), "Computer Science"); assertEquals(faculty.getFacultyMembers().size(), 2); } }
------------------------------------------------------- T E S T S ------------------------------------------------------- Running org.superbiz.cdi.basic.CourseTest Apache OpenEJB 4.0.0-beta-1 build: 20111002-04:06 http://openejb.apache.org/ INFO - openejb.home = /Users/dblevins/examples/cdi-basic INFO - openejb.base = /Users/dblevins/examples/cdi-basic INFO - Using 'javax.ejb.embeddable.EJBContainer=true' INFO - Configuring Service(id=Default Security Service, type=SecurityService, provider-id=Default Security Service) INFO - Configuring Service(id=Default Transaction Manager, type=TransactionManager, provider-id=Default Transaction Manager) INFO - Found EjbModule in classpath: /Users/dblevins/examples/cdi-basic/target/classes INFO - Beginning load: /Users/dblevins/examples/cdi-basic/target/classes INFO - Configuring enterprise application: /Users/dblevins/examples/cdi-basic INFO - Configuring Service(id=Default Managed Container, type=Container, provider-id=Default Managed Container) INFO - Auto-creating a container for bean cdi-basic.Comp: Container(type=MANAGED, id=Default Managed Container) INFO - Configuring Service(id=Default Stateless Container, type=Container, provider-id=Default Stateless Container) INFO - Auto-creating a container for bean Course: Container(type=STATELESS, id=Default Stateless Container) INFO - Enterprise application "/Users/dblevins/examples/cdi-basic" loaded. INFO - Assembling app: /Users/dblevins/examples/cdi-basic INFO - Jndi(name="java:global/cdi-basic/cdi-basic.Comp!org.apache.openejb.BeanContext$Comp") INFO - Jndi(name="java:global/cdi-basic/cdi-basic.Comp") INFO - Jndi(name="java:global/cdi-basic/Course!org.superbiz.cdi.basic.Course") INFO - Jndi(name="java:global/cdi-basic/Course") INFO - Jndi(name="java:global/EjbModule1833350875/org.superbiz.cdi.basic.CourseTest!org.superbiz.cdi.basic.CourseTest") INFO - Jndi(name="java:global/EjbModule1833350875/org.superbiz.cdi.basic.CourseTest") INFO - Created Ejb(deployment-id=Course, ejb-name=Course, container=Default Stateless Container) INFO - Created Ejb(deployment-id=cdi-basic.Comp, ejb-name=cdi-basic.Comp, container=Default Managed Container) INFO - Created Ejb(deployment-id=org.superbiz.cdi.basic.CourseTest, ejb-name=org.superbiz.cdi.basic.CourseTest, container=Default Managed Container) INFO - Started Ejb(deployment-id=Course, ejb-name=Course, container=Default Stateless Container) INFO - Started Ejb(deployment-id=cdi-basic.Comp, ejb-name=cdi-basic.Comp, container=Default Managed Container) INFO - Started Ejb(deployment-id=org.superbiz.cdi.basic.CourseTest, ejb-name=org.superbiz.cdi.basic.CourseTest, container=Default Managed Container) INFO - Deployed Application(path=/Users/dblevins/examples/cdi-basic) Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 1.126 sec Results : Tests run: 1, Failures: 0, Errors: 0, Skipped: 0