| = CDI @Inject |
| :jbake-date: 2016-09-06 |
| :jbake-type: page |
| :jbake-tomeepdf: |
| :jbake-status: published |
| |
| Example cdi-basic can be browsed at https://github.com/apache/tomee/tree/master/examples/cdi-basic |
| |
| |
| 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. |
| |
| = Example |
| |
| 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. |
| |
| == Faculty <small>a basic injectable pojo</small> |
| |
| |
| [source,java] |
| ---- |
| 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; |
| } |
| |
| } |
| ---- |
| |
| |
| == Course <small>a simple session bean</small> |
| |
| |
| [source,java] |
| ---- |
| @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; |
| } |
| } |
| ---- |
| |
| |
| = Test Case |
| |
| |
| [source,java] |
| ---- |
| 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); |
| } |
| } |
| ---- |
| |
| |
| = Running |
| |
| |
| |
| [source] |
| ---- |
| ------------------------------------------------------- |
| T E S T S |
| ------------------------------------------------------- |
| Running org.superbiz.cdi.basic.CourseTest |
| Apache OpenEJB 4.0.0-beta-1 build: 20111002-04:06 |
| http://tomee.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 |
| ---- |
| |