在业务成的域模型中，类和类之间最普遍的关系就是关联关系，而关联也是有方向的。
就以例子来说明：一个人对应一张身份证。对其进行增删改。
对于人在数据创建表的时候，我们就给他两个字段，一个是id号，一个就是名字。
那么对于身份证也就是两个字段，一个对应于一个人相同的id号，一个就是身份证码。
1 那么来创建数据库表：
人为主表，身份证为从表。
1 create table person( 2 id bigint primary key auto_increment, 3 userName varchar(20) 4 ); 5 6 create table card( 7 id bigint primary key, 8 cardNo varchar(18) 9 );
创建实体类的时候，人要引用身份证卡的信息，同样身份证卡也要引用人这个类。
2 那么来创建实体类：
人：
1 package com.cy.beans; 2 3 import java.io.Serializable; 4 5 public class Person implements Serializable { 6 7 private static final long serialVersionUID = 1L; 8 private long id; 9 private String userName; 10 private Card card;// 卡 一对一关联 11 12 public void person() { 13 14 } 15 16 public long getId() { 17 return id; 18 } 19 20 public void setId(long id) { 21 this.id = id; 22 } 23 24 public String getUserName() { 25 return userName; 26 } 27 28 public void setUserName(String userName) { 29 this.userName = userName; 30 } 31 32 public Card getCard() { 33 return card; 34 } 35 36 public void setCard(Card card) { 37 this.card = card; 38 } 39 40 @Override 41 public String toString() { 42 return "Person [id=" + id + ", userName=" + userName + ", card=" + card 43 + "]"; 44 } 45 46 }
身份证：
1 package com.cy.beans; 2 3 import java.io.Serializable; 4 5 public class Card implements Serializable{ 6 7 8 private static final long serialVersionUID = 1L; 9 10 private long id; 11 private String cardNo; 12 private Person person;//人 一对一关联 13 14 public Card(){ 15 16 } 17 public long getId() { 18 return id; 19 } 20 public void setId(long id) { 21 this.id = id; 22 } 23 public String getCardNo() { 24 return cardNo; 25 } 26 public void setCardNo(String cardNo) { 27 this.cardNo = cardNo; 28 } 29 public Person getPerson() { 30 return person; 31 } 32 public void setPerson(Person person) { 33 this.person = person; 34 } 35 @Override 36 public String toString() { 37 return "Card [id=" + id + ", cardNo=" + cardNo + ", person=" + person 38 + "]"; 39 } 40 41 42 }
现在创建映射文件
Person.hbm.xml
1 <?xml version="1.0" encoding="UTF-8"?> 2 <!DOCTYPE hibernate-mapping PUBLIC 3 "-//Hibernate/Hibernate Mapping DTD 3.0//EN" 4 "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> 5 6 <hibernate-mapping> 7 8 <class name="com.cy.beans.Person" table="person" catalog="j2ee"> <!-- catalog数据库 --> 9 10 <id name="id" type="java.lang.Long"><!-- 此行的ID，为对象的属性ID --> 11 <column name="id"></column><!-- 此行的ID，为表字段ID --> 12 <generator class="increment"></generator><!-- 给id指定生成策略 --> 13 </id> 14 15 <property name="userName" type="java.lang.String"> 16 <column name="userName"></column> 17 </property> 18 19 <!--站在主对象的一方来设置级联关系 --> 20 <!-- cascade定义的是关系两端对象到对象的级联关系,cascade有四個取值，all，none，save-update，delete 21 all : 所有情况下均进行关联操作。 22 none：所有情况下均不进行关联操作。这是默认值。 23 save-update:在执行save/update/saveOrUpdate时进行关联操作。 24 delete：在执行delete时进行关联操作。 --> 25 <one-to-one name="card" class="com.cy.beans.Card" cascade="all"></one-to-one> 26 27 28 </class> 29 30 </hibernate-mapping>
Card.hbm.xml
1 <?xml version="1.0" encoding="UTF-8"?> 2 <!DOCTYPE hibernate-mapping PUBLIC 3 "-//Hibernate/Hibernate Mapping DTD 3.0//EN" 4 "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> 5 6 <hibernate-mapping> 7 <class name="com.cy.beans.Card" table="card" catalog="j2ee"> <!-- catalog数据库 --> 8 <id name="id" type="java.lang.Long"><!-- 此行的ID，为对象的属性ID --> 9 <column name="id"></column><!-- 此行的ID，为表字段ID --> 10 <generator class="foreign"><!-- foreign主键生成器 --> 11 <param name="property">person</param><!--类属性 --> 12 </generator> 13 </id> 14 15 <property name="cardNo" type="java.lang.String"> 16 <column name="cardNo"></column> 17 </property> 18 <!--站在从对象的一方来设置交出约束 --> 19 <!-- name:一对一节点 ，constrained： 约束（必须为true） --> 20 <one-to-one name="person" class="com.cy.beans.Person" constrained="true"></one-to-one> 21 22 </class> 23 </hibernate-mapping>
在hibernate.cfg.xml里添加对象xml文件：
1 <mapping resource="com/cy/xmls/Person.hbm.xml"/> 2 <mapping resource="com/cy/xmls/Card.hbm.xml"/>
工具类：
1 package com.cy.tools; 2 3 import org.hibernate.SessionFactory; 4 import org.hibernate.boot.registry.StandardServiceRegistryBuilder; 5 import org.hibernate.cfg.Configuration; 6 import org.hibernate.service.ServiceRegistry; 7 8 /** 9 * session工厂的工具类 10 * @author acer 11 * 12 */ 13 14 public class HibernateUtils { 15 16 private static Configuration cfg; 17 private static SessionFactory sessionFactory; 18 private static ServiceRegistry serviceRegistry; 19 20 static{ 21 22 cfg = new Configuration().configure(); 23 serviceRegistry = new StandardServiceRegistryBuilder().applySettings(cfg.getProperties()).build(); 24 sessionFactory = cfg.buildSessionFactory(serviceRegistry); 25 26 } 27 28 public static SessionFactory getSessionFactory(){ 29 return sessionFactory; 30 } 31 32 33 34 }
IPersonDao.java接口，定义方法：
1 package com.cy.dao; 2 3 import java.io.Serializable; 4 5 import com.cy.beans.Person; 6 7 public interface IPersonDao { 8 /** 9 * 添加 10 * @param p 11 */ 12 public void savePerson(Person p); 13 /** 14 * 修改 15 * @param p 16 */ 17 public void updatePerson(Person p); 18 /** 19 * 刪除 20 * @param p 21 */ 22 public void deletePerson(Person p); 23 /** 24 * 根据id查询数据 25 * @param cls 26 * @param pk 27 * @return 28 */ 29 public Person getPerson(Class<?> cls,Serializable pk); 30 31 public void findPerson(Person p); 32 33 }
写接口实现：PersonDaoImpl.java
1 package com.cy.dao.impl; 2 3 import java.io.Serializable; 4 5 import org.hibernate.Session; 6 import org.hibernate.Transaction; 7 8 import com.cy.beans.Person; 9 import com.cy.dao.IPersonDao; 10 import com.cy.tools.HibernateUtils; 11 12 public class PersonDaoImpl implements IPersonDao { 13 14 @Override 15 public void savePerson(Person p) { 16 //获得Session 17 Session session=null; 18 Transaction transaction=null; 19 20 try { 21 session=HibernateUtils.getSessionFactory().openSession();// 22 transaction=session.beginTransaction();//开启事务 23 session.save(p);//添加 24 transaction.commit();//提交事务 25 } catch (Exception e) { 26 e.printStackTrace(); 27 transaction.rollback();//回滚事务 28 }finally{ 29 session.close();//关闭session 30 } 31 32 } 33 34 @Override 35 public void updatePerson(Person p) { 36 Session session=null; 37 Transaction transaction=null; 38 39 try { 40 session=HibernateUtils.getSessionFactory().openSession(); 41 transaction=session.beginTransaction(); 42 session.update(p);//修改 43 transaction.commit(); 44 } catch (Exception e) { 45 e.printStackTrace(); 46 transaction.rollback(); 47 }finally{ 48 session.close(); 49 } 50 51 } 52 53 @Override 54 public Person getPerson(Class<?> cls, Serializable pk) { 55 Session session=null; 56 Transaction transaction=null; 57 Person person=null; 58 try { 59 session=HibernateUtils.getSessionFactory().openSession(); 60 transaction=session.beginTransaction(); 61 person=(Person) session.get(cls, pk);//根据id查询。pk这里指的就是id 62 transaction.commit(); 63 64 } catch (Exception e) { 65 e.printStackTrace(); 66 transaction.rollback(); 67 }finally{ 68 session.close(); 69 } 70 71 return person; 72 } 73 @Override 74 public void deletePerson(Person p) { 75 Session session=null; 76 Transaction transaction=null; 77 78 try { 79 session=HibernateUtils.getSessionFactory().openSession(); 80 transaction=session.beginTransaction(); 81 session.delete(p);//删除 82 transaction.commit(); 83 } catch (Exception e) { 84 e.printStackTrace(); 85 transaction.rollback(); 86 }finally{ 87 session.close(); 88 } 89 90 } 91 92 93 @Override 94 public void findPerson(Person p) { 95 96 } 97 98 }
写IPersonServer.java接口
1 package com.cy.server; 2 3 import java.io.Serializable; 4 5 import com.cy.beans.Person; 6 7 public interface IPersonServer { 8 /** 9 * 添加 10 * @param p 11 */ 12 public void savePerson(Person p); 13 /** 14 * 修改 15 * @param p 16 */ 17 public void updatePerson(Person p); 18 /** 19 * 刪除 20 * @param p 21 */ 22 public void deletePerson(Long id); 23 /** 24 * 根据id查询 25 * @param cls 26 * @param pk 27 * @return 28 */ 29 public Person getPerson(Class<?> cls,Serializable pk); 30 31 public void findPerson(Person p); 32 }
写PersonServerImpl.java实现；
1 package com.cy.server.impl; 2 3 import java.io.Serializable; 4 5 import com.cy.beans.Person; 6 import com.cy.dao.IPersonDao; 7 import com.cy.dao.impl.PersonDaoImpl; 8 import com.cy.server.IPersonServer; 9 10 public class PersonServerImpl implements IPersonServer { 11 IPersonDao dao = new PersonDaoImpl(); 12 13 @Override 14 public void savePerson(Person p) { 15 dao.savePerson(p); 16 17 } 18 19 @Override 20 public void updatePerson(Person p) { 21 dao.updatePerson(p); 22 } 23 24 @Override 25 public void deletePerson(Long id) { 26 Person p = dao.getPerson(Person.class, id); 27 if (p != null) { 28 dao.deletePerson(p); 29 } 30 31 } 32 33 @Override 34 public Person getPerson(Class<?> cls, Serializable pk) { 35 36 return dao.getPerson(cls, pk); 37 } 38 39 @Override 40 public void findPerson(Person p) { 41 42 } 43 44 }
写个PersonAction测试；
1 package com.cy.action; 2 3 import com.cy.beans.Card; 4 import com.cy.beans.Person; 5 import com.cy.server.IPersonServer; 6 import com.cy.server.impl.PersonServerImpl; 7 8 public class PersonAction { 9 public static void main(String[] args) { 10 11 // savePerson(); 12 // updatePerson(); 13 deletePerson(); 14 } 15 16 private static void deletePerson() { 17 IPersonServer ps=new PersonServerImpl(); 18 ps.deletePerson(Long.valueOf(1)); 19 20 21 } 22 23 private static void updatePerson() { 24 IPersonServer ps=new PersonServerImpl(); 25 Person p=ps.getPerson(Person.class, Long.valueOf(1)); 26 p.setUserName("小紅"); 27 ps.updatePerson(p); 28 /*Hibernate: //这些hibernate所执行语句 修查询 后修改 29 select 30 person0_.id as id1_1_0_, 31 person0_.userName as userName2_1_0_, 32 card1_.id as id1_0_1_, 33 card1_.cardNo as cardNo2_0_1_ 34 from 35 j2ee.person person0_ 36 left outer join 37 j2ee.card card1_ 38 on person0_.id=card1_.id 39 where 40 person0_.id=? 41 Hibernate: 42 update 43 j2ee.person 44 set 45 userName=? 46 where 47 id=? 48 Hibernate: 49 update 50 j2ee.card 51 set 52 cardNo=? 53 where 54 id=? 55 */ 56 57 58 } 59 60 private static void savePerson() { 61 IPersonServer ps=new PersonServerImpl(); 62 Person p=new Person(); 63 p.setUserName("小明"); 64 Card c=new Card(); 65 c.setCardNo("511123************"); 66 //設置相互 67 p.setCard(c); 68 c.setPerson(p); 69 ps.savePerson(p); 70 /*Hibernate: 添加时 先查询主表的最大的id，先添加主表，在添加从表。 删除时则是先删除从表，在删除主表。 71 select 72 max(id) 73 from 74 person 75 Hibernate: 76 insert 77 into 78 j2ee.person 79 (userName, id) 80 values 81 (?, ?) 82 Hibernate: 83 insert 84 into 85 j2ee.card 86 (cardNo, id) 87 values 88 (?, ?) 89 90 91 */ 92 93 } 94 }
