復(fù)合主鍵，由多個(gè)字段組成主鍵，例如，使用firstname和lastname組成主鍵。
可以通過兩種方式確定主鍵，一種是基于實(shí)體類的復(fù)合主鍵，另一種是通過定義主鍵類來實(shí)現(xiàn)。
不管通過哪種方式，復(fù)合主鍵都需要實(shí)現(xiàn)equals方法和hashcode方法，以作為不同數(shù)據(jù)之間是別的標(biāo)志。
一.基于實(shí)體類屬性的復(fù)合主鍵
主鍵由實(shí)體類中的屬性組成。
1.
配置文件TUser.hbm.xml
<?xml?version="1.0"?>
<!DOCTYPE?hibernate-mapping?PUBLIC?"-//Hibernate/Hibernate?Mapping?DTD?3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
????<class?name="cn.blogjava.start.TUser"?table="t_user"?catalog="sample">
????????<composite-id>
????????????<key-property?name="lastname"?column="lastname"?type="string"?/>
????????????<key-property?name="firstname"?column="firstname"?type="string"?/>
????????</composite-id>
????????<property?name="age"?type="integer"?column="age"/>
????</class>
</hibernate-mapping>
2.
TUser.java
package?cn.blogjava.start;
import?org.apache.commons.lang.builder.EqualsBuilder;
import?org.apache.commons.lang.builder.HashCodeBuilder;
/**
?*?TUser?generated?by?hbm2java
?*/
public?class?TUser?implements?java.io.Serializable?{
????//?Fields????
????private?Integer?age;
????private?String?firstname;
????private?String?lastname;
????public?Integer?getAge()?{
????????return?age;
????}
????public?void?setAge(Integer?age)?{
????????this.age?=?age;
????}
????public?String?getFirstname()?{
????????return?firstname;
????}
????public?void?setFirstname(String?firstname)?{
????????this.firstname?=?firstname;
????}
????public?String?getLastname()?{
????????return?lastname;
????}
????public?void?setLastname(String?lastname)?{
????????this.lastname?=?lastname;
????}
????
????public?boolean?equals(Object?obj)?{
????????if(!(obj?instanceof?TUser))?{
????????????return?false;
????????}
????????
????????TUser?user?=?(TUser)obj;
????????return?new?EqualsBuilder()????????? // EqualsBuilder 和HashCodeBuilder均為apache common lang包中的工具類
????????????.appendSuper(super.equals(obj))
????????????.append(this.lastname,?user.lastname)
????????????.append(this.firstname,?user.firstname)
????????????.isEquals();????????
????}
????
????public?int?hasCode()?{
????????return?new?HashCodeBuilder(-528253723,?-475504089)
????????????.appendSuper(super.hashCode())
????????????.append(this.lastname).append(this.firstname)
????????????.toHashCode();
????????????
????}
}
3.
測試類HibernateTest.java
package?cn.blogjava.start;
import?junit.framework.Assert;
import?junit.framework.TestCase;
import?org.hibernate.HibernateException;
import?org.hibernate.Session;
import?org.hibernate.SessionFactory;
import?org.hibernate.Transaction;
import?org.hibernate.cfg.Configuration;
public?class?HibernateTest?extends?TestCase?{
????
????Session?session?=?null;
????/**
?????*?JUnit中的setUp方法在TestCase初始化的時(shí)候會(huì)自動(dòng)調(diào)用
?????*?一般用于初始化公用資源
?????*/
????protected?void?setUp()?{
????????try?{
????????????/**
?????????????*?可以采用hibernate.properties或者h(yuǎn)ibernate.cfg.xml
?????????????*?配置文件的初始化代碼
?????????????*?
?????????????*?采用hibernate.properties
?????????????*?Configuration?config?=?new?Configuration()；
?????????????*?config.addClass(TUser.class);
?????????????*/
????????????
????????????//采用hibernate.cfg.xml配置文件，與上面的方法對(duì)比，兩個(gè)差異
????????????//1.Configuration的初始化方式
????????????//2.xml
????????????Configuration?config?=?new?Configuration().configure();
????????????SessionFactory?sessionFactory?=?config.buildSessionFactory();
????????????session?=?sessionFactory.openSession();
????????????
????????}?catch?(HibernateException?e)?{
????????????//?TODO:?handle?exception
????????????e.printStackTrace();
????????}????????
????}
????/**
?????*?JUnit中的tearDown方法在TestCase執(zhí)行完畢的時(shí)候會(huì)自動(dòng)調(diào)用
?????*?一般用于釋放資源
?????*/????
????protected?void?tearDown()?{
????????try?{
????????????session.close();????????
????????}?catch?(HibernateException?e)?{
????????????//?TODO:?handle?exception
????????????e.printStackTrace();
????????}????????
????}????
????
????/**
?????*?對(duì)象持久化測試(Insert方法)
?????*/????????
????public?void?testInsert()?{
????????Transaction?tran?=?null;
????????try?{
????????????tran?=?session.beginTransaction();
????????????TUser?user?=?new?TUser();
????????????user.setFirstname("bai");
????????????user.setLastname("yunfeng");
????????????user.setAge(26);
????????????session.save(user);
????????????session.flush();
????????????tran.commit();
????????}?catch?(HibernateException?e)?{
????????????//?TODO:?handle?exception
????????????e.printStackTrace();
????????????Assert.fail(e.getMessage());
????????????if(tran?!=?null)?{
????????????????try?{
????????????????????tran.rollback();
????????????????}?catch?(Exception?e1)?{
????????????????????//?TODO:?handle?exception
????????????????????e1.printStackTrace();
????????????????}
????????????}
????????}
????}
????
????/**
?????*?對(duì)象讀取測試(Select方法)
?????*/????????????
????public?void?testSelect(){
????????TUser?user?=?new?TUser();
????????user.setFirstname("bai");
????????user.setLastname("yunfeng");
????????
????????user?=?(TUser)session.load(TUser.class,?user);
????????Assert.assertEquals(user.getAge().intValue(),?26);
????}
}
posted on 2006-07-05 14:48
knowhow 閱讀(328)
評(píng)論(0) 編輯 收藏 所屬分類:
ORM：Hibernate及其他