JPA教程 - JPA一对一主键连接列示例

例子

下面的代码来自Person.java。

package cn.w3cschool.common;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;@Entity
public class Person {@Id@GeneratedValue(strategy=GenerationType.IDENTITY)private long id;private String name;@OneToOne@PrimaryKeyJoinColumnprivate 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;}@Overridepublic String toString() {return "Person [id=" + id + ", name=" + name + "]";}}

下面的代码来自Department.java。

package cn.w3cschool.common;import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToOne;@Entity
public class Department {@Id@GeneratedValue(strategy=GenerationType.IDENTITY)private long id;private String name;@OneToOne(mappedBy="department") private Person person;public Person getPerson() {return person;}public void setPerson(Person person) {this.person = person;}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;}
}

下面的代码来自PersonDaoImpl.java。

package cn.w3cschool.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);d.setPerson(p1);em.persist(p1);em.persist(d);}@PersistenceContextprivate EntityManager em;
}

以下是数据库转储。

Table Name: DEPARTMENTRow:Column Name: ID,Column Type: BIGINT:Column Value: 1Column Name: NAME,Column Type: VARCHAR:Column Value: DesignTable Name: PERSONRow:Column Name: ID,Column Type: BIGINT:Column Value: 1Column Name: NAME,Column Type: VARCHAR:Column Value: Tom

JPA教程 - JPA一对一映射级联示例

以下代码显示如何为一对一映射设置级联操作。

  @OneToOne(cascade=CascadeType.ALL,mappedBy="department")private Person person;

例子

下面的代码来自Department.java。

package cn.w3cschool.common;import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToOne;@Entity
public class Department {@Id@GeneratedValue(strategy=GenerationType.IDENTITY)private long id;private String name;@OneToOne(cascade=CascadeType.ALL,mappedBy="department")private Person person;public Person getPerson() {return person;}public void setPerson(Person person) {this.person = person;}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;}@Overridepublic String toString() {return "Department [id=" + id + ", name=" + name + ", person=" + person+ "]";}
}

下面的代码来自PersonDaoImpl.java。

package cn.w3cschool.common;import java.util.List;import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;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);d.setPerson(p1);em.persist(p1);em.persist(d);Query query = em.createQuery("SELECT e FROM Person e");List<Person> list = (List<Person>) query.getResultList();System.out.println(list.get(0).getDepartment());em.remove(list.get(0));}@PersistenceContextprivate EntityManager em;
}

下面的代码来自Person.java。

package cn.w3cschool.common;
import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
@Entity
public class Person {@Id@GeneratedValue(strategy=GenerationType.IDENTITY)private long id;private String name;@OneToOne(cascade=CascadeType.ALL)@JoinColumn(name="DEPT_ID")   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;}@Overridepublic String toString() {return "Person [id=" + id + ", name=" + name + "]";}}