One-to-many Association Mapping Annotation
One-to-many associations are declared at the property level with the annotation @OneToMany. One to many associations may be bidirectional.
A unidirectional one to many with join table is much preferred. This association is described through an@JoinTable.
@OneToMany(cascade = CascadeType.ALL)
@JoinTable(name = "STUDENT_PHONE", joinColumns = { @JoinColumn(name = "STUDENT_ID") }, inverseJoinColumns = { @JoinColumn(name = "PHONE_ID") })
Student.java
package com.candidjava.hibernate;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.OneToMany;
import javax.persistence.Table;
@Entity
@Table(name = "STUDENT")
public class Student {
private long studentId;
private String studentName;
private Set<Phone> studentPhoneNumbers = new HashSet<Phone>(0);
public Student() {
}
public Student(String studentName, Set<Phone> studentPhoneNumbers) {
this.studentName = studentName;
this.studentPhoneNumbers = studentPhoneNumbers;
}
@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;
}
@OneToMany(cascade = CascadeType.ALL)
@JoinTable(name = "STUDENT_PHONE", joinColumns = { @JoinColumn(name = "STUDENT_ID") }, inverseJoinColumns = { @JoinColumn(name = "PHONE_ID") })
public Set<Phone> getStudentPhoneNumbers() {
return this.studentPhoneNumbers;
}
public void setStudentPhoneNumbers(Set<Phone> studentPhoneNumbers) {
this.studentPhoneNumbers = studentPhoneNumbers;
}
}Phone.java
package com.candidjava.hibernate;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name = "PHONE")
public class Phone {
private long phoneId;
private String phoneType;
private String phoneNumber;
public Phone() {
}
public Phone(String phoneType, String phoneNumber) {
this.phoneType = phoneType;
this.phoneNumber = phoneNumber;
}
@Id
@GeneratedValue
@Column(name = "PHONE_ID")
public long getPhoneId() {
return this.phoneId;
}
public void setPhoneId(long phoneId) {
this.phoneId = phoneId;
}
@Column(name = "PHONE_TYPE", nullable = false, length = 10)
public String getPhoneType() {
return this.phoneType;
}
public void setPhoneType(String phoneType) {
this.phoneType = phoneType;
}
@Column(name = "PHONE_NUMBER", nullable = false, length = 15)
public String getPhoneNumber() {
return this.phoneNumber;
}
public void setPhoneNumber(String phoneNumber) {
this.phoneNumber = phoneNumber;
}
}save or inserting record into many to One annotation mapping
public void insertStudent(Student si) {
try {
Session s = getSession();
Transaction transaction = s.beginTransaction();
s.save(si);
transaction.commit();
} catch (HibernateException e) {
e.printStackTrace();
}
}Get or fetch record from many to One annotation mapping
public List<Student> getStudent(long id) {
List ls=null;
try {
Session s = getSession();
ls=s.createCriteria(Student.class).add(Restrictions.eq("studentId",id)).list();
// System.out.println(ls.size());
} catch (HibernateException e) {
System.out.println(e.getMessage());
}
return ls;
}Download
Hibernate One to many annotation war
Hibernate One to Many annotation zip
