Hibernate IdentifierLoadAccess and Session.byId() Example
February 12, 2015
IdentifierLoadAccess identifier = session.byId(Student.class);
IdentifierLoadAccess
org.hibernate.IdentifierLoadAccess loads an entity using the primary identifier . This class has different methods to access entity.getReference(Serializable id): We pass the primary identifier and returns the object and if there is no value corresponding to given identifier, it throws exception.
load(Serializable id) : We pass the primary identifier and returns the object and if there is no value corresponding to given identifier, it does not throw exception but returns null value.
with(LockOptions options) : This method returns same as calling instance that is IdentifierLoadAccess but with lock option like SKIP_LOCKED, NO_WAIT, NONE etc.
Session.byId()
org.hibernate.Session.byId() returns the instance of IdentifierLoadAccess. We can pass identifier either entity class name as Class instance or entity name as a String.Complete Example
Find the complete example for the demo of Hibernate 4 IdentifierLoadAccess and Session.byId().Input Data
Find the print screen of database table which we are using as an input for our demo.
Main Class
Find the main class to access data.IdDemo.java
package com.concretepage;
import org.hibernate.IdentifierLoadAccess;
import org.hibernate.Session;
public class IdDemo {
public static void main(String[] args) {
Session session = HibernateUtil.getSessionFactory().openSession();
IdentifierLoadAccess identifier = session.byId(Student.class);
//Access entity for existing identifier using getReference()
Student student = (Student)identifier.getReference(new Integer(1));
System.out.println("Name:"+ student.getName()+", Age:"+ student.getAge());
//Using load
student = (Student)identifier.load(new Integer(2));
System.out.println("Name:"+ student.getName()+", Age:"+ student.getAge());
//Access entity for non-existing identifier
student = (Student)identifier.load(new Integer(3));
System.out.println(student);
session.close();
}
}
Entity
Find the entity being used in the example.Student.java
package com.concretepage;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name="student")
public class Student {
@Id
@Column(name="id")
private int id;
@Column(name="age")
private int age;
@Column(name="name")
private String name;
public Student(){}
public Student(int id, int age, String name){
this.id = id;
this.age = age;
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
Output
Find the output.Hibernate: select student0_.id as id1_0_0_, student0_.age as age2_0_0_, student0_.name as name3_0_0_ from student student0_ where student0_.id=? Name:Rahim, Age:23 Hibernate: select student0_.id as id1_0_0_, student0_.age as age2_0_0_, student0_.name as name3_0_0_ from student student0_ where student0_.id=? Name:Mahesh, Age:25 Hibernate: select student0_.id as id1_0_0_, student0_.age as age2_0_0_, student0_.name as name3_0_0_ from student student0_ where student0_.id=? null
