@EntityListeners in your entity class

DrRakha

@EntityListeners is used for to do action for specific actions on entity .

Listener class :

Code:

import javax.persistence.PostLoad;
import javax.persistence.PostPersist;
import javax.persistence.PostUpdate;

import codemiles.test.jpa.Comment;

public class ListenerExample {
    
     @PostLoad
     @PostPersist
     @PostUpdate
      public void actionFunction(Comment comment) { 
         
         //  When loading the object . 
         System.out.println("Post load action ");
          
         // When persisting the object .
         System.out.println("Post persist action ");
         
         //When  updating the values of the object 
         System.out.println("Post update action ");
         
         
      }

}
 

Entity class :

Code:

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EntityListeners;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.SequenceGenerator;
import javax.persistence.Table;

import codemiles.test.jpa.listener.ListenerExample;

@EntityListeners({ListenerExample.class})
@Entity
@Table(name="COMMENT")
@SequenceGenerator(sequenceName="COMMENT_SEQ",name="COMMENT_SEQ_GEN")
public class Comment {
    private long id;
    private String content;
    private Topic topic;
    
    public void setId(long id) {
        this.id = id;
    }
    @Id
    @GeneratedValue(generator="COMMENT_SEQ_GEN",strategy=GenerationType.SEQUENCE)
    public long getId() {
        return id;
    }
    
    @Column(name="CONTENT")
    public void setContent(String content) {
        this.content = content;
    }
    public String getContent() {
        return content;
    }
    
    @ManyToOne(fetch =  FetchType.LAZY)
    @JoinColumn(name = "TOPIC_ID", nullable = false)
    public void setTopic(Topic topic) {
        this.topic = topic;
    }
    public Topic getTopic() {
        return topic;
    }
    

}
 

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@EntityListeners in your entity class

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