xml方式处理联合主键：
以有两个主键:id和name的student表为例。
先创建个主键类：
package com.bjsxt.hibernate;
//黑色为必写项
public class StudentPK implements java.io.Serializable{
private int id;
private String name;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public boolean equals(Object o) {
if(o instanceof StudentPK) {
StudentPK pk = (StudentPK)o;
if(this.id == pk.getId() && this.name.equals(pk.getName())) {
return true;
}
}
return false;
}
@Override
public int hashCode() {
return this.name.hashCode();
}
}
写model：
package com.bjsxt.hibernate;
public class Student {
private StudentPK pk;
private int age;
private String sex;
private boolean good;
public boolean isGood() {
return good;
}
public void setGood(boolean good) {
this.good = good;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public StudentPK getPk() {
return pk;
}
public void setPk(StudentPK pk) {
this.pk = pk;
}
}
映射关系：Student.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="com.bjsxt.hibernate.Student">
<composite-id name="pk" class="com.bjsxt.hibernate.StudentPK">
<key-property name="id"></key-property>
<key-property name="name"></key-property>
</composite-id>
<property name="age" />
<property name="sex" />
<property name="good" type="yes_no"></property>
</class>
</hibernate-mapping>
Annotation（注解）处理联合主键
三种方法：
将主键类注解为@Embeddable并将model中的属性——主键类的对象注解为@Id
将主键类的对象充当的组件的属性注解为@EmbeddedId,仍然需要主键类。
将类注解为@IdClass（主键类.class ），并将该实体中所有属于主键的属性都注解为@Id
