hibernate 多对多双向关联
1、一个员工对应一张卡,因此Person与Card之间的关联是一对一关系。
Person类代码如下:
package com.mr.cheng.bean; import java.util.Set; import javax.persistence.CascadeType; import javax.persistence.Entity; import javax.persistence.FetchType; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.JoinTable; import javax.persistence.ManyToMany; import javax.persistence.ManyToOne; import javax.persistence.OneToOne; import org.hibernate.annotations.Cascade; @Entity public class Person { private Integer id; private String name; private int age; private double price; private Card card; @OneToOne (cascade=CascadeType.ALL,fetch=FetchType.LAZY) @JoinColumn(name="cardId") public Card getCard() { return card; } @Override public String toString() { return "Person [id=" + id + ", name=" + name + ", age=" + age + ", price=" + price + ", card=" + card + "]"; } public void setCard(Card card) { this.card = card; } @Id @GeneratedValue public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public double getPrice() { return price; } public void setPrice(double price) { this.price = price; } }
Card类的代码如下:
package com.mr.cheng.bean; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.OneToOne; @Entity public class Card { private int id; private String name; @Id@GeneratedValue public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @OneToOne(mappedBy="card") public Person getPerson() { return person; } @Override public String toString() { return "Card [id=" + id + ", name=" + name + ", person=" + person + "]"; } public void setPerson(Person person) { this.person = person; } private Person person; }
2、测试类
package com.mr.cheng.test; import java.util.Date; import java.util.HashSet; import org.hibernate.Query; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.AnnotationConfiguration; import org.hibernate.tool.hbm2ddl.SchemaExport; import org.junit.AfterClass; import org.junit.BeforeClass; import org.junit.Test; import com.mr.cheng.bean.Card; import com.mr.cheng.bean.Person; public class HibernateTest { private static SessionFactory sessionFactory; //@BeforeClass public static void beforeClass() { sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory(); } //@AfterClass public static void afterClass() { sessionFactory.close(); } @Test public void testSchemaExport() { new SchemaExport(new AnnotationConfiguration().configure()).create(true, true); } public static void main(String[] args) { beforeClass(); } /** * 一对一关联 */ @Test public void testAddPerson(){ sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory(); Session session = sessionFactory.getCurrentSession(); session.beginTransaction(); Person p = new Person(); Card card = new Card(); card.setName("ccc"); p.setAge(3); p.setName("cheg"); p.setCard(card); session.save(p); session.getTransaction().commit(); } @Test public void testAddQueryPerson(){ sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory(); Session session = sessionFactory.getCurrentSession(); session.beginTransaction(); Person p = (Person) session.get(Person.class, 2); System.out.println(p.getCard().getName() + p.getCard().getId()); session.getTransaction().commit(); } @Test public void testAddQueryCard(){ sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory(); Session session = sessionFactory.getCurrentSession(); session.beginTransaction(); session.createCriteria(Card.class).list(); session.getTransaction().commit(); } /** * */ }
3、hibernate.hbm.xml的配置信息如下:
<?xml version=‘1.0‘ encoding=‘utf-8‘?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="connection.driver_class">
com.mysql.jdbc.Driver
</property>
<property name="connection.url">
jdbc:mysql://localhost/test
</property>
<property name="connection.username">root</property>
<property name="connection.password">root</property>
<property name="dialect">
org.hibernate.dialect.MySQLDialect
</property>
<!--
<property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
<property name="connection.url">jdbc:oracle:thin:@localhost:1521:SXT</property>
<property name="connection.username">scott</property>
<property name="connection.password">tiger</property>
<property name="dialect">org.hibernate.dialect.OracleDialect</property>
-->
<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">1</property>
<!-- Enable Hibernate‘s automatic session context management -->
<property name="current_session_context_class">thread</property>
<!-- Disable the second-level cache -->
<property name="cache.provider_class">
org.hibernate.cache.NoCacheProvider
</property>
<!-- Echo all executed SQL to stdout -->
<property name="show_sql">true</property>
<property name="format_sql">true</property>
<mapping class="com.mr.cheng.bean.Card" />
<mapping class="com.mr.cheng.bean.Person" />
</session-factory>
</hibernate-configuration>
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