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>