1.pom.xml文件参考http://my.oschina.net/u/555061/blog/506049
2.这里使用注解方法(其实注解也就注解了2个字段为主键),给出hibernate.cfg.xml配置跟http://my.oschina.net/u/555061/blog/506049相同,只是映射类改为<mapping class="EntityTest.Tour_Morph"/>
3.给出Tour_Morph.java,
package EntityTest;
import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.IdClass;
import javax.persistence.Table;
@Entity
@IdClass(Tour_MorphID.class)
@Table(name = "Tour_Morph")
public class Tour_Morph {
@Id
@Column(name = "Tour_id")
private Integer Tour_id;
@Id
@Column(name = "Morph_id")
private Integer Morph_id;
private String otherField;
public Tour_Morph() {
}
public Tour_Morph(Integer Tour_id, Integer Morph_id, String otherField) {
this.Tour_id = Tour_id;
this.Morph_id = Morph_id;
this.otherField = otherField;
}
public Integer getTour_id() {
return Tour_id;
}
public void setTour_id(Integer tour_id) {
Tour_id = tour_id;
}
public Integer getMorph_id() {
return Morph_id;
}
public void setMorph_id(Integer morph_id) {
Morph_id = morph_id;
}
public String getOtherField() {
return otherField;
}
public void setOtherField(String otherField) {
this.otherField = otherField;
}
}
class Tour_MorphID implements Serializable {
private static final long serialVersionUID = 155771990L;
private Integer Tour_id;
private Integer Morph_id;
public int hashCode() {
int result = 1;
result = Tour_id.hashCode() + Morph_id.hashCode();
return result;
}
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
final Tour_MorphID other = (Tour_MorphID) obj;
if (Tour_id == other.Tour_id && Morph_id == other.Morph_id)
return true;
return false;
}
public Integer getTour_id() {
return Tour_id;
}
public void setTour_id(Integer tour_id) {
Tour_id = tour_id;
}
public Integer getMorph_id() {
return Morph_id;
}
public void setMorph_id(Integer morph_id) {
Morph_id = morph_id;
}
}
4.解释下,这里的关键点在于如何让hibernate编译通过2个字段做主键的情况,默认都是一个字段做主键,所以关键点就是Tour_MorphID.java这个类,Tour_MorphID类的所有字段作为Tour_Morph类的主键
4.1Tour_MorphID implements Serializable 这个是要求
4.2覆盖了hashCode和equals两个方法,
4.3public类注解增加了@IdClass,主键主键@Id有2个,
5.生成的表sql如下,
CREATE TABLE `tour_morph` (
`Morph_id` int(11) NOT NULL,
`Tour_id` int(11) NOT NULL,
`otherField` varchar(255) DEFAULT NULL,
PRIMARY KEY (`Morph_id`,`Tour_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
6.使用的话跟一个主键的用法没有任何区别
public void testBasicUsage() {
// create a couple of events...
Session session = sessionFactory.openSession();
session.beginTransaction();
session.save(new Tour_Morph(1, 11, "otherField1"));
session.save(new Tour_Morph(2, 22, "otherField2"));
session.getTransaction().commit();
session.close();
// now lets pull events from the database and list them
session = sessionFactory.openSession();
session.beginTransaction();
List<Tour_Morph> result = session.createQuery("from Tour_Morph").list();
for (Tour_Morph tour_morph : result) {
System.out.println(tour_morph.getTour_id() + "|"
+ tour_morph.getMorph_id() + "|"
+ tour_morph.getOtherField());
}
session.getTransaction().commit();
session.close();
}
来源:oschina
链接:https://my.oschina.net/u/555061/blog/506131