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Hibernate Mapping

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In this section, you will learn about Hibernate Mapping.

Hibernate Mapping

In this section, you will learn about Hibernate Mapping.

In Hibernate, you can do mapping through XML as well as through annotations in JavaBean classes.

Hibernate contains three major type of mapping :

One to One mapping

The XML mapping file used in one-to-one mapping is given below :

Worker.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="net.roseindia">

<class name="Worker" table="worker">
<id name="workerId" column="worker_id">
<generator class="native" />
</id>
<one-to-one name="workerDetail" class="net.roseindia.WorkerDetail"
cascade="save-update"></one-to-one>

<property name="firstname" column="firstname" />
<property name="lastname" column="lastname" />
<property name="birthDate" type="date" column="birth_date" />
<property name="cellphone" column="cell_phone" />

</class>
</hibernate-mapping>

WorkerDetail.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="net.roseindia">

<class name="WorkerDetail" table="workerdetail">

<id name="workerId" type="java.lang.Long">
<column name="worker_id" />
<generator class="foreign">
<param name="property">worker</param>
</generator>
</id>
<one-to-one name="worker" class="net.roseindia.Worker"
constrained="true"></one-to-one>

<property name="street" column="street" />
<property name="city" column="city" />
<property name="state" column="state" />
<property name="country" column="country" />
</class>

</hibernate-mapping>

One to one mapping using annotations in JavaBean classes is given below :

Worker.java

package net.roseindia;

import java.util.Date;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name = "worker")
public class Worker {

@Id
@GeneratedValue
@Column(name = "worker_id")
private Long workerId;



@Column(name = "firstname")
private String firstname;

@Column(name = "lastname")
private String lastname;

@Column(name = "birth_date")
private Date birthDate;

@Column(name = "cell_phone")
private String cellphone;

@OneToOne(mappedBy = "worker", cascade = CascadeType.ALL)
private WorkerDetail workerDetail;

public Worker() {

}

public Worker(String firstname, String lastname, Date birthdate,
String phone) {
this.firstname = firstname;
this.lastname = lastname;
this.birthDate = birthdate;
this.cellphone = phone;

}

public Long getWorkerId() {
return workerId;
}

public void setWorkerId(Long workerId) {
this.workerId = workerId;
}

public String getFirstname() {
return firstname;
}

public void setFirstname(String firstname) {
this.firstname = firstname;
}

public String getLastname() {
return lastname;
}

public void setLastname(String lastname) {
this.lastname = lastname;
}

public Date getBirthDate() {
return birthDate;
}

public void setBirthDate(Date birthDate) {
this.birthDate = birthDate;
}

public String getCellphone() {
return cellphone;
}

public void setCellphone(String cellphone) {
this.cellphone = cellphone;
}

public WorkerDetail getWorkerDetail() {
return workerDetail;
}

public void setWorkerDetail(WorkerDetail workerDetail) {
this.workerDetail = workerDetail;
}
}

WorkerDetail.java

package net.roseindia;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;
import javax.persistence.Table;
import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.Parameter;

@Entity
@Table(name="workerdetail")
public class WorkerDetail {
@Id
@Column(name="worker_id", unique=true, nullable=false)
@GeneratedValue(generator="gen")
@GenericGenerator(name="gen", strategy="foreign", parameters=@Parameter(name="property", value="worker"))
private Long workerId;

@Column(name="street")
private String street;

@Column(name="city")
private String city;

@Column(name="state")
private String state;

@Column(name="country")
private String country;

@OneToOne
@PrimaryKeyJoinColumn
private Worker worker;

public WorkerDetail() {

}

public WorkerDetail(String street, String city, String state, String country) {
this.street = street;
this.city = city;
this.state = state;
this.country = country;
}

public Long getWorkerId() {
return workerId;
}

public void setWorkerId(Long workerId) {
this.workerId = workerId;
}

public String getStreet() {
return street;
}

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

public String getCity() {
return city;
}

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

public String getState() {
return state;
}

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

public String getCountry() {
return country;
}

public void setCountry(String country) {
this.country = country;
}

public Worker getWorker() {
return worker;
}

public void setWorker(Worker worker) {
this.worker = worker;
}
}

One to Many Mapping

The one to many relation between two tables is shown below :

The XML one-to-many mapping is given below:

Address.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="net.roseindia">
<class name="Address" table="address">
<id name="addressId" column="address_id">
<generator class="native" />
</id>
<property name="street" column="street"/>
<property name="city" column="city"/>
<property name="state" column="state"/>
<property name="country" column="country"/>
<set name="employees" table="employee"
inverse="true" lazy="true" fetch="select">
<key>
<column name="address_id" not-null="true" />
</key>
<one-to-many class="net.roseindia.Employee" />
</set>
</class>
</hibernate-mapping>

Employee.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="net.roseindia">

<class name="Employee" table="employee">
<id name="employeeId" column="employee_id">
<generator class="native" />
</id>

<property name="firstname" column="firstname"/>
<property name="lastname" column="lastname" />
<property name="cellphone" column="cell_phone" />

<many-to-one name="address" class="net.roseindia.Address" fetch="select">
<column name="address_id" not-null="true" />
</many-to-one>

</class>
</hibernate-mapping>

One-to-many mapping using annotations in JavaBean classes  is given below :

Address.java

package net.roseindia;

import java.util.Set;

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

@Entity
@Table(name = "address")
public class Address {
@Id
@GeneratedValue
@Column(name = "address_id")
private Long addressId;

@Column(name = "street")
private String street;

@Column(name = "city")
private String city;

@Column(name = "state")
private String state;

@Column(name = "country")
private String country;

@OneToMany(mappedBy = "address")
private Set<Employee> employees;

public Long getAddressId() {
return addressId;
}

public void setAddressId(Long addressId) {
this.addressId = addressId;
}

public String getStreet() {
return street;
}

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

public String getCity() {
return city;
}

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

public String getState() {
return state;
}

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

public String getCountry() {
return country;
}

public void setCountry(String country) {
this.country = country;
}

public Set<Employee> getEmployees() {
return employees;
}

public void setEmployees(Set<Employee> employees) {
this.employees = employees;
}
}

Employee.java

package net.roseindia;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

@Entity
@Table(name="employee")
public class Employee {
@Id
@GeneratedValue
@Column(name="employee_id")
private Long employeeId;

@Column(name="firstname")
private String firstname;

@Column(name="lastname")
private String lastname;

@Column(name="cell_phone")
private String cellphone;

@ManyToOne
@JoinColumn(name="address_id")
private Address address;

public Address getAddress() {
return address;
}

public void setAddress(Address address) {
this.address = address;
}

public Employee() {}

public Employee(String firstname, String lastname, String phone) {
this.firstname = firstname;
this.lastname = lastname;
this.cellphone = phone;
}

public Long getEmployeeId() {
return employeeId;
}

public void setEmployeeId(Long employeeId) {
this.employeeId = employeeId;
}

public String getFirstname() {
return firstname;
}

public void setFirstname(String firstname) {
this.firstname = firstname;
}

public String getLastname() {
return lastname;
}

public void setLastname(String lastname) {
this.lastname = lastname;
}

public String getCellphone() {
return cellphone;
}

public void setCellphone(String cellphone) {
this.cellphone = cellphone;
}
}

Many to Many Mapping

The XML Many to Many relation shown below using figure:

The XML many-to-many mapping is given below :

Student.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="net.roseindia">
<class name="Student" table="student">
<id name="studentId" column="student_id">
<generator class="native" />
</id>

<property name="studentName" column="student_name"/>

<set name="courses" table="student_course"
inverse="false" lazy="true" fetch="select" cascade="all">
<key column="student_id" />
<many-to-many column="course_id" class="Course" />
</set>
</class>
</hibernate-mapping>

Course.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="net.roseindia">
<class name="Course" table="course">
<id name="courseId" column="course_id">
<generator class="native" />
</id>

<property name="courseName" column="course_name"/>

<set name="students" table="student_course"
inverse="false" lazy="true" fetch="select" cascade="all">
<key column="student_id" />
<many-to-many column="course_id" class="Course" />
</set>
</class>
</hibernate-mapping>

Many-to-Many mapping using annotations in JavaBean classes  is given below :

Student.java

package net.roseindia;

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.ManyToMany;
import javax.persistence.Table;

@Entity
@Table(name="student")
public class Student {
@Id
@Column(name="student_id")
@GeneratedValue
private Long studentId;

@Column(name="student_name")
private String studentName ;

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

public Student() {
}

public Long getStudentId() {
return studentId;
}

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

public String getStudentName() {
return studentName;
}

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

@ManyToMany(cascade = {CascadeType.ALL})
@JoinTable(name="student_course",joinColumns={@JoinColumn(name="student_id")},inverseJoinColumns={@JoinColumn(name="course_id")})
private Set<Course> courses = new HashSet<Course>();

public Set<Course> getCourses() {
return courses;
}

public void setCourses(Set<Course> courses) {
this.courses = courses;
} 
}

Course.java

package net.roseindia;

import java.util.HashSet;
import java.util.Set;

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

@Entity
@Table(name = "course")
public class Course {
@Id
@Column(name = "course_id")
@GeneratedValue
private Long courseId;

@Column(name = "course_name")
private String courseName;

@ManyToMany(mappedBy="courses")
private Set<Student> students = new HashSet<Student>();

public Course() {
}

public Course(String courseName) {
this.courseName = courseName;
}

public Set<Student> getStudents() {
return students;
}

public void setStudents(Set<Student> students) {
this.students = students;
}

public Long getCourseId() {
return courseId;
}

public void setCourseId(Long courseId) {
this.courseId = courseId;
}

public String getCourseName() {
return courseName;
}

public void setCourseName(String courseName) {
this.courseName = courseName;
}
}
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Posted on: April 20, 2012

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