Hibernate Component mapping Annotation tutorial Embedded mapping

Component dependent object

A component is a contained object that is persisted as a value type and not an entity reference. The term "component" refers to the object-oriented notion of composition and not to architecture-level components. 

Historically Hibernate called these components. JPA calls them embeddables. Either way the concept is the same: a composition of values. For example we might have a Name class that is a composition of first-name and last-name, or an Address class that is a composition of street, city, postal code, etc.

The @Embeddable annotation is used to specify embeddable types. Like basic types, embeddable types do not have any identity, being managed by their owning entity.

The @Embedded annotation is used to specify that a given entity attribute represents an embeddable type.

Component Annotation @Embedded mapping

package com.vaannila.student;

import javax.persistence.Column;
import javax.persistence.Embedded;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "student")
public class Student {

	private long studentId;
	private String studentName;
	private Address studentAddress;

	public Student() {
	}

	public Student(String studentName, Address studentAddress) {
		this.studentName = studentName;
		this.studentAddress = studentAddress;
	}

	@Id
	@GeneratedValue
	@Column(name = "STUDENT_ID")
	public long getStudentId() {
		return this.studentId;
	}

	public void setStudentId(long studentId) {
		this.studentId = studentId;
	}

	@Column(name = "STUDENT_NAME", nullable = false, length = 100)
	public String getStudentName() {
		return this.studentName;
	}

	public void setStudentName(String studentName) {
		this.studentName = studentName;
	}

	@Embedded
	public Address getStudentAddress() {
		return this.studentAddress;
	}

	public void setStudentAddress(Address studentAddress) {
		this.studentAddress = studentAddress;
	}

}

package com.vaannila.student;

import javax.persistence.Column;
import javax.persistence.Embeddable;

@Embeddable
public class Address {

	private String street;
	private String city;
	private String state;
	private String zipcode;

	public Address() {
	}

	public Address(String street, String city, String state, String zipcode) {
		this.street = street;
		this.city = city;
		this.state = state;
		this.zipcode = zipcode;
	}

	@Column(name = "ADDRESS_STREET", nullable = false, length = 250)
	public String getStreet() {
		return this.street;
	}

	public void setStreet(String street) {
		this.street = street;
	}

	@Column(name = "ADDRESS_CITY", nullable = false, length = 50)
	public String getCity() {
		return this.city;
	}

	public void setCity(String city) {
		this.city = city;
	}

	@Column(name = "ADDRESS_STATE", nullable = false, length = 50)
	public String getState() {
		return this.state;
	}

	public void setState(String state) {
		this.state = state;
	}

	@Column(name = "ADDRESS_ZIPCODE", nullable = false, length = 10)
	public String getZipcode() {
		return this.zipcode;
	}

	public void setZipcode(String zipcode) {
		this.zipcode = zipcode;
	}

}

	public void insertStudent(Student student) {
		Session s = getSession();
		Transaction transaction = s.beginTransaction();
		s.save(student);
		transaction.commit();
	}

public Student getStudent(long id) {
		Student sd = null;
		Session s = getSession();
		sd = (Student) s.get(Student.class, id);
		return sd;
}

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