hibernate--联合主键--XML

xml:composite-id

要重写equals,hashCode方法, 还要序列化

1. 新建一个主键类: StudentPK.java, 注意需要序列化.还要重写equals和hashCode:　

package com.bjsxt.hibernate;

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();
	}
}

　　

   

2. 删掉Student.java里的id和name的set和get方法, 新建一个主键对象及setter和getter:     

package com.bjsxt.hibernate;

public class Student {
	private StudentPK pk;
	private int age;
	public StudentPK getPk() {
		return pk;
	}
	public void setPk(StudentPK pk) {
		this.pk = pk;
	}
	
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
}

3. junit的测试方法改成:

@Test
	public void testStudentSave() {
		StudentPK pk=new StudentPK();
		pk.setId(1);
		pk.setName("zhangsan");
		Student s =new Student();
		s.setPk(pk);		
		s.setAge(23);
		
		Session session =  sf.openSession();
		session.beginTransaction();
		session.save(s);
		session.getTransaction().commit();
		session.close();	
	}

　　

4. Student.hbm.xml改成:

<?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 package="com.bjsxt.hibernate">
    <class name="Student" table="_student">
        <!-- <id name="id">
        	<generator class="native"></generator>
        </id>
        <property name="name"/> -->
        <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"/>
    </class>
</hibernate-mapping>