Java/EJB3/Annotation

Discriminator Value in entity hierarchy

   <source lang="java">

File: EmployeeService.java

import javax.ejb.Stateless; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; @Stateless public class EmployeeService implements EmployeeServiceLocal, EmployeeServiceRemote {

 @PersistenceContext(unitName="EmployeeService")
 EntityManager em;
 
 public EmployeeService() {
 }
 public void doAction(){
   Person p = new Person();
   p.setFirstName("P");
   p.setLastName("P");
   em.persist(p);
   Customer cust = new Customer();
   cust.setFirstName("C");
   cust.setLastName("C");
   cust.setStreet("Street");
   cust.setCity("City");
   cust.setState("State");
   cust.setZip("11111");
   em.persist(cust);
   Employee employee = new Employee();
   employee.setFirstName("E");
   employee.setLastName("E");
   employee.setStreet("1st Street");
   employee.setCity("E City");
   employee.setState("E State");
   employee.setZip("33333");
   employee.setEmployeeId(15);
   em.persist(employee);
   
   em.flush();
   System.out.println("saved");
   
 }

}

File: EmployeeServiceLocal.java

import java.util.Collection; import javax.ejb.Local; @Local public interface EmployeeServiceLocal {

   public void doAction();

}

File: EmployeeServiceRemote.java

import java.util.Collection; import javax.ejb.Remote; @Remote public interface EmployeeServiceRemote{

 public void doAction();  

}

File: Employee.java import javax.persistence.DiscriminatorColumn; import javax.persistence.DiscriminatorType; import javax.persistence.DiscriminatorValue; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.Inheritance; import javax.persistence.InheritanceType; import javax.persistence.Table;

@Entity public class Employee extends Customer {

  private int employeeId;
  public int getEmployeeId() { return employeeId; }
  public void setEmployeeId(int id) { employeeId = id; }

}

@Entity @DiscriminatorValue("CUST") class Customer extends Person {

  private String street;
  private String city;
  private String state;
  private String zip;
  
  public String getStreet() { return street; }
  public void setStreet(String street) { this.street = street; }
  public String getCity() { return city; }
  public void setCity(String city) { this.city = city; }
  public String getState() { return state; }
  public void setState(String state) { this.state = state; }
  public String getZip() { return zip; }
  public void setZip(String zip) { this.zip = zip; }

}

@Entity @Table(name="PERSON_HIERARCHY") @Inheritance(strategy=InheritanceType.SINGLE_TABLE) @DiscriminatorColumn(name="DISCRIMINATOR",

                    discriminatorType=DiscriminatorType.STRING)

@DiscriminatorValue("PERSON") class Person implements java.io.Serializable {

  private int id;
  private String firstName;
  private String lastName;
  @Id @GeneratedValue
  public int getId() { return id; }
  public void setId(int id) { this.id = id; }
  public String getFirstName() { return firstName; }
  public void setFirstName(String first) { this.firstName = first; }
  public String getLastName() { return lastName; }
  public void setLastName(String last) { this.lastName = last; }

}

File: Main.java import java.util.Collection; import javax.naming.InitialContext;

public class Main {

 public static void main(String[] a) throws Exception {
   EmployeeServiceRemote service = null;
   // Context compEnv = (Context) new InitialContext().lookup("java:comp/env");
   // service = (HelloService)new InitialContext().lookup("java:comp/env/ejb/HelloService");
   service = (EmployeeServiceRemote) new InitialContext().lookup("EmployeeService/remote");
   
   
   
   
   service.doAction();
 }

}

File: jndi.properties java.naming.factory.initial=org.jnp.interfaces.NamingContextFactory java.naming.factory.url.pkgs=org.jboss.naming:org.jnp.interfaces java.naming.provider.url=localhost:1099

      </source>
   
  
 
  

Mark Ejb Method With Our Own Annotation

   <source lang="java">

File: Employee.java import javax.persistence.Entity; import javax.persistence.EntityListeners; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.PostRemove; @Entity public class Employee implements java.io.Serializable {

 private int id;
 private String firstName;
 private String lastName;
 @Id
 @GeneratedValue
 public int getId() {
   return id;
 }

 @PostRemove
 public void postRemove()
 {
    System.out.println("@PostRemove");
 }
 public void setId(int id) {
   this.id = id;
 }
 public String getFirstName() {
   return firstName;
 }
 public void setFirstName(String first) {
   this.firstName = first;
 }
 public String getLastName() {
   return lastName;
 }
 public void setLastName(String last) {
   this.lastName = last;
 }

}

File: EmployeeService.java import javax.ejb.Stateless; import javax.transaction.TransactionManager; @Stateless public class EmployeeService implements EmployeeServiceLocal, EmployeeServiceRemote {

 public EmployeeService() {
 }
 
 @JndiInjected("java:/TransactionManager")
 TransactionManager tm;
 public void doAction() throws Exception {
   System.out.println("Is there a transaction: " + (tm.getTransaction() != null));
 }

}

File: EmployeeServiceLocal.java

import java.util.Collection; import javax.ejb.Local; @Local public interface EmployeeServiceLocal {

   public void doAction()  throws Exception;

}

File: EmployeeServiceRemote.java

import java.util.Collection; import javax.ejb.Remote; @Remote public interface EmployeeServiceRemote{

 public void doAction()  throws Exception;  

}

File: JndiInjected.java

import java.lang.annotation.*; @Target({ElementType.METHOD, ElementType.FIELD}) @Retention(RetentionPolicy.RUNTIME) public @interface JndiInjected {

  String value();

}

File: JndiInjector.java

import java.lang.reflect.*; import javax.ejb.*; import javax.interceptor.*; import javax.naming.*; import javax.annotation.PostConstruct; public class JndiInjector {

  @PostConstruct
  public void jndiInject(InvocationContext invocation) {
     Object target = invocation.getTarget();
     Field[] fields = target.getClass().getDeclaredFields();
     Method[] methods = target.getClass().getDeclaredMethods();
     // find all @JndiInjected fields methods and set them
     try {
        InitialContext ctx = new InitialContext();
        for (Method method : methods) {
           JndiInjected inject = method.getAnnotation(JndiInjected.class);
           if (inject != null) {
              Object obj = ctx.lookup(inject.value());
              method.setAccessible(true);
              method.invoke(target, obj);
           }
        }
        for (Field field : fields) {
           JndiInjected inject = field.getAnnotation(JndiInjected.class);
           if (inject != null) {
              Object obj = ctx.lookup(inject.value());
              field.setAccessible(true);
              field.set(target, obj);
           }
        }
        invocation.proceed();
     } catch (Exception ex) {
        throw new EJBException("Failed to execute @JndiInjected", ex);
     }
  }

}

File: Main.java import java.util.Date; import javax.naming.InitialContext;

public class Main {

 public static void main(String[] a) throws Exception {
   EmployeeServiceRemote service = null;
   // Context compEnv = (Context) new InitialContext().lookup("java:comp/env");
   // service = (HelloService)new InitialContext().lookup("java:comp/env/ejb/HelloService");
   service = (EmployeeServiceRemote) new InitialContext().lookup("EmployeeService/remote");
   
   

   service.doAction();
 }

}

File: jndi.properties java.naming.factory.initial=org.jnp.interfaces.NamingContextFactory java.naming.factory.url.pkgs=org.jboss.naming:org.jnp.interfaces java.naming.provider.url=localhost:1099

      </source>