标签:div nbsp ati log pen pack .config style nat
简要聊一聊 组合主键映射
一:组合主键映射(数据库中某张表有多个主键)
比如有一个学生成绩类,有属性:stuId,subjectId,result. 其中stuId 和 subjectId 对应映射表中的组合主键(stuId,subjectId)
1、编写组合主键的类,该类必须实现Serializable接口
1 package cn.pojo; 2 3 import java.io.Serializable; 4 5 public class ScoreId implements Serializable{ 6 private int stuId; 7 private int subjectId; 8 9 public int getStuId() { 10 return stuId; 11 } 12 public void setStuId(int stuId) { 13 this.stuId = stuId; 14 } 15 public int getSubjectId() { 16 return subjectId; 17 } 18 public void setSubjectId(int subjectId) { 19 this.subjectId = subjectId; 20 } 21 22 }
2、在主类中引用该类
1 package cn.pojo; 2 3 public class Score { 4 private ScoreId scoreId; 5 private int resule; 6 7 public ScoreId getScoreId() { 8 return scoreId; 9 } 10 public void setScoreId(ScoreId scoreId) { 11 this.scoreId = scoreId; 12 } 13 public int getResule() { 14 return resule; 15 } 16 public void setResule(int resule) { 17 this.resule = resule; 18 } 19 20 }
3、编写映射文件
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="cn.pojo"> <class name="Score"> <composite-id name="scoreId" class="ScoreId"> <key-property name="stuId"></key-property> <key-property name="subjectId"></key-property> </composite-id> <property name="result"></property> </class> </hibernate-mapping>
4、测试
package cn.test; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; import cn.pojo.Score; import cn.pojo.ScoreId; public class TestHibernate { public static void main(String[] args) { //通过Configuration对象创建SessionFactory对象 SessionFactory sf = new Configuration().configure().buildSessionFactory(); //创建Session对象 Session s = sf.openSession(); //开启事务 s.beginTransaction(); //我们只需要关注这里的事务。 Score score = new Score(); ScoreId si = new ScoreId(); si.setStuId(1); si.setSubjectId(3); score.setScoreId(si); score.setResult(89); s.save(score); //提交事务 s.getTransaction().commit(); //关闭Session s.close(); //关闭SessionFactory sf.close(); } }
标签:div nbsp ati log pen pack .config style nat
原文地址:http://www.cnblogs.com/DogLiLoveCat/p/7182110.html