Hibernate复合主键

复合主键，由多个字段组成主键，例如，使用一个用户的firstname和lastname组成主键。

可以通过两种方式确定主键，一种是基于实体类的复合主键，另一种是通过定义主键类来实现。

不管通过哪种方式，复合主键都需要实现equals方法和hashcode方法，以作为不同数据之间是别的标志。

一.基于实体类属性的复合主键

主键由实体类中的属性组成。

1.映射文件TUser.hbm.xml

xml 代码

<? 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 =
"cn.blogjava.start.TUser" table="t_user"
catalog =
"sample" >
< composite-id>

<
key-property name ="lastname"
column =
"lastname" type ="string"
/>
< key-property name
= "firstname"
column ="firstname"
type =
"string" />
</
composite-id >

<
property name ="age"
type =
"integer" column ="age"
/>
</ class>

</ hibernate-mapping>

2.TUser.java

java 代码

package cn.blogjava.start;

import org.apache.commons.lang.builder.EqualsBuilder;
import org.apache.commons.lang.builder.HashCodeBuilder;

/**
* TUser generated by hbm2java
*/

public class TUser implements java.io.Serializable {

// Fields

private Integer age;

private String firstname;

private String lastname;

public Integer getAge() {
return age;
}

public void setAge(Integer age) {
this.age = age;
}

public String getFirstname() {
return firstname;
}

public void setFirstname(String firstname) {
this.firstname = firstname;
}

public String getLastname() {
return lastname;
}

public void setLastname(String lastname) {
this.lastname = lastname;
}

public boolean equals(Object obj) {
if(!(obj instanceof TUser)) {
return false;
}

TUser user = (TUser)obj;
return new EqualsBuilder() // EqualsBuilder 和HashCodeBuilder均为apache common lang包中的工具类
.appendSuper( super.equals(obj))
.append( this.lastname, user.lastname)
.append( this.firstname, user.firstname)
.isEquals();
}

public int hasCode() {
return new HashCodeBuilder(-528253723, -
475504089)
.appendSuper( super.hashCode())
.append( this.lastname).append(this.firstname)

.toHashCode();

}

}

3.测试类HibernateTest.java

java 代码

package cn.blogjava.start;

import junit.framework.Assert;
import junit.framework.TestCase;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

public class HibernateTest extends TestCase {

Session session = null;
/**

* JUnit中的setUp方法在TestCase初始化的时候会自动调用
* 一般用于初始化公用资源

*/
protected void setUp() {
try {
/**
* 可以采用hibernate.properties或者hibernate.cfg.xml
* 配置文件的初始化代码
*
* 采用hibernate.properties
* Configuration config = new Configuration()；
* config.addClass(TUser.class);
*/

//采用hibernate.cfg.xml配置文件，与上面的方法对比，两个差异
//1.Configuration的初始化方式
//2.xml
Configuration config = new Configuration().configure();
SessionFactory sessionFactory = config.buildSessionFactory();
session = sessionFactory.openSession();

} catch (HibernateException e) {
// TODO: handle exception
e.printStackTrace();
}
}

/**

* JUnit中的tearDown方法在TestCase执行完毕的时候会自动调用
* 一般用于释放资源

*/
protected void tearDown() {
try {
session.close();
} catch (HibernateException e) {
// TODO: handle exception
e.printStackTrace();
}
}

/**
* 对象持久化测试(Insert方法)
*/
public void testInsert() {
Transaction tran = null;
try {
tran = session.beginTransaction();
TUser user = new TUser();
user.setFirstname(
"bai" );
user.setLastname( "yunfeng");
user.setAge( 26);
session.save(user);
session.flush();
tran.commit();
} catch (HibernateException e) {
// TODO: handle exception
e.printStackTrace();
Assert.fail(e.getMessage());
if(tran != null) {
try {
tran.rollback();
} catch (Exception e1) {
// TODO: handle exception
e1.printStackTrace();
}
}
}
}

/**

* 对象读取测试(Select方法)
*/

public void testSelect(){
TUser user = new TUser();
user.setFirstname( "bai");
user.setLastname( "yunfeng");

user = (TUser)session.load(TUser.
class , user);
Assert.assertEquals(user.getAge().intValue(), 26);

}
}

二、基于主键类的复合主键：

方法：将主键字段从POJO类中提出了，生成一个主键类。

可以将1中的例子加以改造，将firstname和lastname字段单独提取到一个主键类中。

1.

配置文件TUser.hbm.xml

composite-id节点的name指定了实体类中的主键类的属性名.

xml 代码

<? 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
= "cn.blogjava.start"
>
<
class name =
"TUser" table ="t_user"
catalog =
"sample" >
< composite-id name
= "userPK"
class =
"TUserPK" >
<
key-property name ="lastname"
column =
"lastname" type ="string"
/>
< key-property name
= "firstname"
column ="firstname"
type =
"string" />
</
composite-id >

<
property name ="age"
type =
"integer" column ="age"
/>
</ class>

</ hibernate-mapping>

2.POJO类

package cn.blogjava.start;

/**
* TUser generated by hbm2java
*/

public class TUser implements java.io.Serializable {

// Fields

private Integer age;

//配置文件composite-id的name属性
private TUserPK userPK;

public Integer getAge() {
return age;
}

public void setAge(Integer age) {
this.age = age;
}

public TUserPK getUserPK() {
return userPK;
}

public void setUserPK(TUserPK userPK) {
this.userPK = userPK;
}
}

3.主键类TUserPK.java

java 代码

package cn.blogjava.start;

import java.io.Serializable;

import org.apache.commons.lang.builder.EqualsBuilder;
import org.apache.commons.lang.builder.HashCodeBuilder;

public class TUserPK implements Serializable {

private String firstname;
private String lastname;

public String getFirstname() {
return firstname;
}

public void setFirstname(String firstname) {

this.firstname = firstname;
}

public String getLastname() {
return lastname;
}

public void setLastname(String lastname) {

this.lastname = lastname;
}

public boolean equals(Object obj) {
if(!(obj instanceof TUserPK)) {
return false;
}

TUserPK userPK = (TUserPK)obj;
return new EqualsBuilder()
.appendSuper( super.equals(obj))
.append( this.lastname, userPK.lastname)
.append( this.firstname, userPK.firstname)
.isEquals();
}

public int hasCode() {
return new HashCodeBuilder(-528253723, -
475504089)
.appendSuper( super.hashCode())
.append( this.lastname).append(this.firstname)

.toHashCode();
}
}

4.测试代码HibernateTest.java

java 代码

package cn.blogjava.start;

import junit.framework.Assert;
import junit.framework.TestCase;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

public class HibernateTest extends TestCase {

Session session = null;
/**

* JUnit中的setUp方法在TestCase初始化的时候会自动调用
* 一般用于初始化公用资源

*/
protected void setUp() {
try {
/**
* 可以采用hibernate.properties或者hibernate.cfg.xml
* 配置文件的初始化代码
*
* 采用hibernate.properties
* Configuration config = new Configuration()；
* config.addClass(TUser.class);
*/

//采用hibernate.cfg.xml配置文件，与上面的方法对比，两个差异
//1.Configuration的初始化方式
//2.xml
Configuration config = new Configuration().configure();
SessionFactory sessionFactory = config.buildSessionFactory();
session = sessionFactory.openSession();

} catch (HibernateException e) {
// TODO: handle exception
e.printStackTrace();
}
}

/**

* JUnit中的tearDown方法在TestCase执行完毕的时候会自动调用
* 一般用于释放资源

*/
protected void tearDown() {
try {
session.close();
} catch (HibernateException e) {
// TODO: handle exception
e.printStackTrace();
}
}

/**
* 对象持久化测试(Insert方法)
*/
public void testInsert() {
Transaction tran = null;
try {
tran = session.beginTransaction();
TUser user = new TUser();
TUserPK userPK =
new TUserPK();
userPK.setFirstname( "yu");
userPK.setLastname(
"yy" );
user.setUserPK(userPK);
user.setAge( 25);
session.save(user);
session.flush();
tran.commit();
} catch (HibernateException e) {
// TODO: handle exception
e.printStackTrace();
Assert.fail(e.getMessage());
if(tran != null) {
try {
tran.rollback();
} catch (Exception e1) {
// TODO: handle exception
e1.printStackTrace();
}
}
}
}

/**

* 对象读取测试(Select方法)
*/

public void testSelect(){
TUserPK userPK = new TUserPK();
userPK.setFirstname( "yu");
userPK.setLastname( "yy");

TUser user = (TUser)session.load(TUser.
class , userPK);
Assert.assertEquals(user.getAge().intValue(), 25);

}
}

以上内容来自：http://www.blogjava.net/zoninge/archive/2009/01/05/249928.html

三 复合主键注解方式
联合主键用Hibernate注解映射方式主要有三种：

第一、将联合主键的字段单独放在一个类中，该类需要实现java.io.Serializable接口并重写equals和hascode，再将该类注解为@Embeddable,最后在主类中(该类不包含联合

主键类中的字段)保存该联合主键类的一个引用，并生成set和get方法，并将该引用注解为@Id

第二、将联合主键的字段单独放在一个类中，该类需要实现java.io.Serializable接口并重写equals和hascode，最后在主类中(该类不包含联合主键类中的字段)保存该联合主

键类的一个引用，并生成set和get方法，并将该引用注解为@EmbeddedId

第三、将联合主键的字段单独放在一个类中，该类需要实现java.io.Serializable接口并要重写equals和hashcode.最后在主类中(该类包含联合主键类中的字段)将联合主键字

段都注解为@Id,并在该类上方将上这样的注解：@IdClass(联合主键类.class)

下面以第三种方式举例：

1.POJO类

package com.red.bean;
import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.IdClass;
import javax.persistence.Table;

@Entity
@IdClass(DoctorPK.class)
@Table(name="t_doctor")
public class Doctor implements Serializable
{
private static final long serialVersionUID = 1L;

private DoctorPK doctorpk = null;

private String sex = "";

public DoctorPK getDoctorpk() {
return doctorpk;
}
public void setDoctorpk(DoctorPK doctorpk) {
this.doctorpk = doctorpk;
}
public String getSex()
{
return sex;
}
public void setSex(String sex)
{
this.sex = sex;
}
}

2. 主键类DoctorPK.java

在所有主键字段上加@Id注解符号

java 代码

package com.red.bean;
import java.io.Serializable;
import javax.persistence.Id;
import org.apache.commons.lang3.builder.EqualsBuilder;
import org.apache.commons.lang3.builder.HashCodeBuilder;
public class DoctorPK implements Serializable
{
private static final long serialVersionUID = 1L;
@Id
private String firstName = "";
@Id
private String lastName = "";

public String getFirstName()
{
return firstName;
}
public void setFirstName(String firstName)
{
this.firstName = firstName;
}
public String getLastName()
{
return lastName;
}
public void setLastName(String lastName)
{
this.lastName = lastName;
}

public  int hasCode()
{
return  new HashCodeBuilder(- 528253723, - 475504089 )
.appendSuper( super.hashCode())
.append( this.lastName).append( this.firstName)
.toHashCode();
}

public boolean equals(Object obj)
{

if(!(obj instanceof DoctorPK))
{
return false;
}

DoctorPK userPK = (DoctorPK)obj;

return  new EqualsBuilder()
.appendSuper( super.equals(obj))
.append( this.lastName, userPK.lastName)
.append( this.firstName, userPK.firstName)
.isEquals();
}
}

3.测试代码

package com.red.test;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import com.red.bean.Doctor;
import com.red.bean.DoctorPK;
import junit.framework.Assert;
import junit.framework.TestCase;
public class TestDoactorCase extends TestCase {

private Session session = null;
private SessionFactory sf = null;
protected void setUp()
{
try
{
AnnotationConfiguration cfg = new AnnotationConfiguration();
sf = cfg.configure().buildSessionFactory();
session = sf.openSession();
}
catch( HibernateException e)
{
e.printStackTrace();
}
}
protected void tearDown()
{
try
{
session.close();
sf.close();
}
catch(HibernateException e)
{
e.printStackTrace();
}

}

public void testInsert()
{
try
{
DoctorPK docpk = new DoctorPK();
docpk.setFirstName("li");
docpk.setLastName("guoliang");
Doctor dc = new Doctor();
dc.setSex("0");
dc.setDoctorpk(docpk);

session.beginTransaction();
session.save(dc);
session.getTransaction().commit();
}
catch (HibernateException e)
{
e.printStackTrace();
}
}

public void testSelect()
{
DoctorPK docpk = new DoctorPK();
docpk.setFirstName("li");
docpk.setLastName("guoliang");
Doctor dr = (Doctor) session.load(Doctor.class, docpk);

Assert.assertEquals("0".equals(dr.getSex()) , true);
}
}