Java Tutorial/JPA/EntityListener

Add Entity Listeners To subclasses

File: EmployeeDebugListener.java

import javax.persistence.PostLoad;
import javax.persistence.PrePersist;
import javax.persistence.PreRemove;
import javax.persistence.PreUpdate;
public class EmployeeDebugListener {
  @PostLoad
  public void postLoad(Employee emp) {
    System.out.println("EmployeeDebugListener.Load called on employee id: " + emp.getId());
  }
}

Entity Listener: PostLoad

File: EmployeeDebugListener.java

import javax.persistence.PostLoad;
import javax.persistence.PrePersist;
import javax.persistence.PreRemove;
import javax.persistence.PreUpdate;
public class EmployeeDebugListener {
  @PostLoad
  public void postLoad(Employee emp) {
    System.out.println("EmployeeDebugListener.Load called on employee id: " + emp.getId());
  }
}

Entity Listener: PreRemove

File: Employee.java

import javax.persistence.Entity;
import javax.persistence.EntityListeners;
import javax.persistence.Id;
import javax.persistence.PostLoad;
import javax.persistence.PostPersist;
import javax.persistence.PostUpdate;
import javax.persistence.PrePersist;
import javax.persistence.PreRemove;
import javax.persistence.PreUpdate;
import javax.persistence.Transient;
@Entity
@EntityListeners({EmployeeDebugListener.class})
public class Employee {
    @Id private int id;
    private String name;
    @Transient private long syncTime;
    @PostPersist 
    @PostUpdate
    @PostLoad 
    private void resetSyncTime() {
        syncTime = System.currentTimeMillis(); 
        System.out.println("Employee.resetSyncTime called on employee id: " + getId());
    }
    public long getCachedAge() {
        return System.currentTimeMillis() - syncTime; 
    }
    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    public String toString() {
        return "Employee id: " + getId() ;
    }
}

Entity Listener: PreUpdate

File: EmployeeDebugListener.java

import javax.persistence.PostLoad;
import javax.persistence.PrePersist;
import javax.persistence.PreRemove;
import javax.persistence.PreUpdate;
public class EmployeeDebugListener {
  @PreUpdate
  public void preUpdate(Employee emp) {
    System.out.println("EmployeeDebugListener.Update called on employee id: " + emp.getId());
  }
}

Entity Listeners PrePersist

File: Employee.java

import javax.persistence.Entity;
import javax.persistence.EntityListeners;
import javax.persistence.Id;
import javax.persistence.PostLoad;
import javax.persistence.PostPersist;
import javax.persistence.PostUpdate;
import javax.persistence.PrePersist;
import javax.persistence.PreRemove;
import javax.persistence.PreUpdate;
import javax.persistence.Transient;
@Entity
@EntityListeners({EmployeeDebugListener.class, NameValidator.class})
public class Employee {
    @Id private int id;
    private String name;
    @Transient private long syncTime;
    @PostPersist 
    @PostUpdate
    @PostLoad 
    private void resetSyncTime() {
        syncTime = System.currentTimeMillis(); 
        System.out.println("Employee.resetSyncTime called on employee id: " + getId());
    }
    public long getCachedAge() {
        return System.currentTimeMillis() - syncTime; 
    }
    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    public String toString() {
        return "Employee id: " + getId() ;
    }
}

Exclude Super class Listeners In Super Class

File: EmployeeDebugListener.java

import javax.persistence.PostLoad;
import javax.persistence.PrePersist;
import javax.persistence.PreRemove;
import javax.persistence.PreUpdate;
public class EmployeeDebugListener {
  @PostLoad
  public void postLoad(Employee emp) {
    System.out.println("EmployeeDebugListener.Load called on employee id: " + emp.getId());
  }
}

One Entity With Two Listeners

File: EmployeeDebugListener.java

import javax.persistence.PostLoad;
import javax.persistence.PrePersist;
import javax.persistence.PreRemove;
import javax.persistence.PreUpdate;
public class EmployeeDebugListener {
  @PrePersist
  public void prePersist(Employee emp) {
    System.out.println("EmployeeDebugListener.Persist called on employee id: " + emp.getId());
  }
}