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 @Override41 public String toString() {42 return "Person [id=" + id + ", userName=" + userName + ", card=" + card43 + "]";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 @Override36 public String toString() {37 return "Card [id=" + id + ", cardNo=" + cardNo + ", person=" + person38 + "]";39 }40 41 42 }
现在创建映射文件
Person.hbm.xml
1 2 5 67 8 9 10 29 3011 14 1512 13 16 18 19 20 2517 26 27 28
Card.hbm.xml
1 2 5 67 8 239 14 1510 11 person 12 1316 18 19 2017 21 22
在hibernate.cfg.xml里添加对象xml文件：
12
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 acer11 *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 p11 */12 public void savePerson(Person p);13 /**14 * 修改15 * @param p16 */17 public void updatePerson(Person p);18 /**19 * 刪除20 * @param p21 */22 public void deletePerson(Person p);23 /**24 * 根据id查询数据25 * @param cls26 * @param pk27 * @return28 */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 @Override15 public void savePerson(Person p) {16 //获得Session17 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session30 }31 32 }33 34 @Override35 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 @Override54 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id62 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 @Override74 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 @Override94 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 p11 */12 public void savePerson(Person p);13 /**14 * 修改15 * @param p16 */17 public void updatePerson(Person p);18 /**19 * 刪除20 * @param p21 */22 public void deletePerson(Long id);23 /**24 * 根据id查询25 * @param cls26 * @param pk27 * @return28 */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 @Override14 public void savePerson(Person p) {15 dao.savePerson(p);16 17 }18 19 @Override20 public void updatePerson(Person p) {21 dao.updatePerson(p);22 }23 24 @Override25 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 @Override34 public Person getPerson(Class cls, Serializable pk) {35 36 return dao.getPerson(cls, pk);37 }38 39 @Override40 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 select30 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 from35 j2ee.person person0_ 36 left outer join37 j2ee.card card1_ 38 on person0_.id=card1_.id 39 where40 person0_.id=?41 Hibernate: 42 update43 j2ee.person 44 set45 userName=? 46 where47 id=?48 Hibernate: 49 update50 j2ee.card 51 set52 cardNo=? 53 where54 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 select72 max(id) 73 from74 person75 Hibernate: 76 insert 77 into78 j2ee.person79 (userName, id) 80 values81 (?, ?)82 Hibernate: 83 insert 84 into85 j2ee.card86 (cardNo, id) 87 values88 (?, ?)89 90 91 */92 93 }94 }