JPA Entity Example | Java Persistence API
September 06, 2013
JPA Entity is a java class referring to database table. It contains setter and getter method to save and fetch data from database. JPA provides annotation to correlate plain java class to a table and its attributes to table columns. The package of javax.persistence contains all the annotations to create an entity. Some basic annotation will be discussed below.
@Entity
@Entity is the javax.persistence.Entity in java persistence API. A java class becomes JPA entity only when the class is annotated with @Entity.@Table
@Table is javax.persistence.Table which specifies the table name associated with the given Entity. Entity name and column name can be different but if @Table has not been provided to entity, by default entity will associate the table with the same name as entity.@Column
@Column is javax.persistence.Column. @Column is used to associate a column and an entity attribute.@Id
@Id is javax.persistence.Id. @Id enables an attribute of an entity to behave like a primary key of a table.Sample Entity is given below.
Farmer.java
package com.concretepage.entity;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name="farmer")
public class Farmer {
@Id
@Column(name="id")
private int id;
@Column(name="name")
private String name;
@Column(name="village")
private String village;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getVillage() {
return village;
}
public void setVillage(String village) {
this.village = village;
}
}
Download the source code which is a demo for end to end use of entity with a JPA application.
Download Source Code
jpa-entity-example.zip
