hibernate 联合主键

1.假设id和name是联合主键，应用面向对象的思想，单独设计一个类作为主键类。

Student.java

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 getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}*/
	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;
	}	
	
}

2.StudentPk.java

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;
	}
	
	//保证唯一性，重写equals和hashCode
	
	@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();
	}
}

3.HibernateIDTest.java

package com.bjsxt.hibernate;

import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

public class HibernateIDTest {
	private static SessionFactory sessionFactory;
	
	@BeforeClass
	public static void beforeClass() {
			sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();
	}
	@AfterClass
	public static void afterClass() {
		sessionFactory.close();
	}
	
	@Test
	public void testStudentSave() {
		StudentPK pk = new StudentPK();
		pk.setId(1);
		pk.setName("zhangsan");
		Student s = new Student();
		s.setPk(pk);
		s.setAge(8);
		
		
		Session session = sessionFactory.getCurrentSession();
		session.beginTransaction();
		session.save(s);
		session.getTransaction().commit();
	}
	
	@Test
	public void testTeacherSave() {
	
		Teacher t = new Teacher();
		t.setId(1);
		t.setName("t1");
		t.setTitle("middle");
		t.setBirthDate(new Date());
		
		Session session = sessionFactory.getCurrentSession();
		session.beginTransaction();
		session.save(t);
		session.getTransaction().commit();
	}
	
	public static void main(String[] args) {
		beforeClass();
	}
}

4.Student.hbm.xml

<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版本的联合主键

下面是定义组合主键的几种语法:

• 将组件类注解为@Embeddable,并将组件的属性注解为@Id
• 将组件的属性注解为@EmbeddedId
• 将类注解为@IdClass,并将该实体中所有属于主键的属性都注解为@Id

TeacherPK.java

package com.bjsxt.hibernate;

import javax.persistence.Embeddable;


public class TeacherPK 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 TeacherPK) {
			TeacherPK pk = (TeacherPK)o;
			if(this.id == pk.getId() && this.name.equals(pk.getName())) {
				return true;
			}
		}
		return false;
	}
	
	@Override
	public int hashCode() {
		return this.name.hashCode();
	}
}

Teacher.java

package com.bjsxt.hibernate;

import java.util.Date;

import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.EnumType;
import javax.persistence.Enumerated;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.IdClass;
import javax.persistence.SequenceGenerator;

import javax.persistence.Id;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import javax.persistence.Transient;

@Entity
@javax.persistence.TableGenerator(
	    name="Teacher_GEN",
	    table="GENERATOR_TABLE",
	    pkColumnName = "pk_key",
	    valueColumnName = "pk_value",
	    pkColumnValue="Teacher",
	    allocationSize=1
	)

@SequenceGenerator(name="teacherSEQ", sequenceName="teacherSEQ_DB")
@IdClass(TeacherPK.class)
public class Teacher {
	//private TeacherPK pk;
	private int id;
	private String name;
	private String title; 
	private String yourWifeName;
	private Date birthDate;
	private boolean good;
	private Gender gender;
	
	@Enumerated(EnumType.STRING)
	public Gender getGender() {
		return gender;
	}
	public void setGender(Gender gender) {
		this.gender = gender;
	}
	public boolean isGood() {
		return good;
	}
	public void setGood(boolean good) {
		this.good = good;
	}
	@Transient
	public String getYourWifeName() {
		return yourWifeName;
	}
	public void setYourWifeName(String yourWifeName) {
		this.yourWifeName = yourWifeName;
	}
	@Id
	@GeneratedValue(strategy=GenerationType.TABLE, generator="Teacher_GEN")
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	
	@Id
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getTitle() {
		return title;
	}
	public void setTitle(String title) {
		this.title = title;
	}
	@Temporal(TemporalType.TIME)
	public Date getBirthDate() {
		return birthDate;
	}
	public void setBirthDate(Date birthDate) {
		this.birthDate = birthDate;
	}
	
	/*@EmbeddedId
	public TeacherPK getPk() {
		return pk;
	}
	public void setPk(TeacherPK pk) {
		this.pk = pk;
	}*/
}