[Java][JPA] Listener & Callback example

Console.txt

[EL Info]: connection: 2015-08-30 12:52:11.554--ServerSession(1286783232)--/file:/C:/Users/KiT/IdeaProjects/Database Sample/service/target/classes/_pu login successful
Employee.prePersist
[EL Fine]: sql: 2015-08-30 12:52:11.635--ClientSession(1437983537)--Connection(1614079837)--INSERT INTO EMPLOYEE (NAME, SALARY) VALUES (?, ?)
	bind => [2 parameters bound]
[EL Fine]: sql: 2015-08-30 12:52:11.637--ClientSession(1437983537)--Connection(1614079837)--SELECT LAST_INSERT_ID()
Employee.postPersist
========================================
[EL Fine]: sql: 2015-08-30 12:52:11.729--ServerSession(1286783232)--Connection(1614079837)--SELECT ID, NAME, SALARY FROM EMPLOYEE WHERE (ID = ?)
	bind => [1 parameter bound]
Employee.postLoad
[EL Info]: connection: 2015-08-30 12:52:11.734--ServerSession(1286783232)--/file:/C:/Users/KiT/IdeaProjects/Database Sample/service/target/classes/_pu logout successful

LogListener.java

import javax.persistence.*;

public class LogListener {
    @PrePersist
    public void prePersist(Object object) { // MUST have a parameter
        System.out.println("Employee.prePersist");
    }

    @PostPersist
    public void postPersist(Object object) {  // MUST have a parameter
        System.out.println("Employee.postPersist");
    }

    @PostLoad
    public void postLoad(Object object) { // MUST have a parameter
        System.out.println("Employee.postLoad");
    }

    ... // more callback functions
}

ServiceJPA.java

import javax.persistence.*;

public class ServiceJPA {

    public static void create(EntityManager manager) {
        EntityTransaction transaction = manager.getTransaction();
        transaction.begin();

        Employee employee = new Employee("KiT", 123456789);
        manager.persist(employee);

        transaction.commit();
    }

    public static void load(EntityManager manager, int id) {
        EntityTransaction transaction = manager.getTransaction();
        transaction.begin();

        Employee employee = manager.find(Employee.class, id);

        transaction.commit();
    }

    public static void main(String[] args) {
        EntityManagerFactory factory = Persistence.createEntityManagerFactory("pu");
        EntityManager manager = factory.createEntityManager();

        create(manager);
        System.out.println("========================================");
        load(manager, 1);

        manager.close();
        factory.close();
    }
}

User.java

import javax.persistence.*;

@Entity
@EntityListeners(LogListener.class)
public class Employee {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    private String name;
    private long salary;

    @Override
    public String toString() {
        return String.format("Employee #%d: %s (%d)", id, name, salary);
    }
}

• Callback functions
• Listeners