The following code shows how to do one to one mapping with lazy load setting.
@OneToOne(fetch=LAZY)
private Department department;
The following code is from Person.java.
package com.java2s.common; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.OneToOne; import static javax.persistence.FetchType.LAZY; @Entity public class Person { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private long id; private String name; @OneToOne(fetch=LAZY) private Department department; public Person() {} public Person(String name) { this.name = name; } public Department getDepartment() { return department; } public void setDepartment(Department department) { this.department = department; } public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public String toString() { return "Person [id=" + id + ", name=" + name + "]"; } }
The following code is from Department.java.
package com.java2s.common; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; @Entity public class Department { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private long id; private String name; public long getId() { return id; } public void setId(long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } }
The following code is from PersonDaoImpl.java.
package com.java2s.common; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; import org.springframework.transaction.annotation.Transactional; @Transactional public class PersonDaoImpl { public void test(){ Person p1 = new Person("Tom"); p1.setName("Tom"); Department d = new Department(); d.setName("Design"); p1.setDepartment(d); em.persist(p1); em.persist(d); } @PersistenceContext private EntityManager em; }
The following is the database dump.
Table Name: DEPARTMENT Row: Column Name: ID, Column Type: BIGINT: Column Value: 1 Column Name: NAME, Column Type: VARCHAR: Column Value: Design Table Name: PERSON Row: Column Name: ID, Column Type: BIGINT: Column Value: 1 Column Name: NAME, Column Type: VARCHAR: Column Value: Tom Column Name: DEPARTMENT_ID, Column Type: BIGINT: Column Value: 1