两种方式配置Hibernate复合主键(修正)

最新推荐文章于 2018-01-03 17:27:12 发布

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#hibernate #class #user #import #equals #table

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本文介绍如何在Hibernate中定义复合主键及其映射方式，包括使用复合主键类实现序列化接口并重写equals与hashCode方法，以及在Hibernate映射文件中配置复合主键。

数据库结构

create table component(name varchar(50) not null,
                       sex varchar(50) not null,
                       description varchar(50),
                       primary key(name,sex));

主键类，一定要实现Serializable接口，并改写equals和hascode方法

package component;

import java.io.Serializable;

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

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

public class ComponentPK implements Serializable {

private String name;

private String sex;

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public String getSex() {

return sex;

}

public void setSex(String sex) {

this.sex = sex;

}

public boolean equals(Object obj) {

if(obj == this) {

return true;

}

if(!(obj instanceof Component)) {

return false;

}

ComponentPK componentpk = (ComponentPK) obj;

return new EqualsBuilder()

.append(this.name, componentpk.getName())

.append(this.sex, componentpk.getSex())

.isEquals();

}

public int hashCode() {

return new HashCodeBuilder()

.append(this.name)

.append(this.sex)

.toHashCode();

}

package component;

public class Component {

private String description;

private ComponentPK componentpk;

public ComponentPK getComponentpk() {

return componentpk;

}

public void setComponentpk(ComponentPK componentpk) {

this.componentpk = componentpk;

}

public String getDescription() {

return description;

}

public void setDescription(String description) {

this.description = description;

}

HBM文件

<?xml version="1.0" encoding="utf-8"?>

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<!--

Mapping file autogenerated by MyEclipse - Hibernate Tools

-->

<hibernate-mapping package="component">

<composite-id name="componentpk"

class="ComponentPK"

unsaved-value="any">

<key-property name="name"

column="name"

type="java.lang.String"/>

<key-property name="sex"

column="sex"

type="java.lang.String"/>

</composite-id>

</class>

</hibernate-mapping>

测试代码：

public static void main(String[] args) {

Configuration cfg=new Configuration();

cfg.configure();

SessionFactory sf=cfg.buildSessionFactory();

Session session=sf.openSession();

Transaction t=session.beginTransaction();

ComponentPK pk=new ComponentPK();

pk.setName("1");

pk.setSex("3");

Component component=new Component();

component.setComponentpk(pk);

component.setDescription("12");

session.save(component);

t.commit();

System.out.println("success");

}

如果组成复合主键的某一个属性是其他持久话类的话，则需要使用<key many-to-one>

增加表User:

CREATE TABLE `user` (
`id` varchar(50) NOT NULL,
`pass` varchar(50) default NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=gb2312;

增加持久化类User及相应的Mapping文件

package component;

public class User {

private String id;

private String pass;

public String getId() {

return id;

}

public void setId(String id) {

this.id = id;

}

public String getPass() {

return pass;

}

public void setPass(String pass) {

this.pass = pass;

}

<?xml version="1.0" encoding="utf-8"?>

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<!--

Mapping file autogenerated by MyEclipse - Hibernate Tools

-->

<hibernate-mapping package="component">

</id>

</class>

</hibernate-mapping>

修改ComponentPK类

package component;

import java.io.Serializable;

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

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

public class ComponentPK implements Serializable {

private String name;

private String sex;

private User user;

public User getUser() {

return user;

}

public void setUser(User user) {

this.user = user;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public String getSex() {

return sex;

}

public void setSex(String sex) {

this.sex = sex;

}

public boolean equals(Object obj) {

if(obj == this) {

return true;

}

if(!(obj instanceof Component)) {

return false;

}

ComponentPK componentpk = (ComponentPK) obj;

return new EqualsBuilder()

.append(this.name, componentpk.getName())

.append(this.sex, componentpk.getSex())

.isEquals();

}

public int hashCode() {

return new HashCodeBuilder()

.append(this.name)

.append(this.sex)

.toHashCode();

}

修改Component.hbm.xml

<hibernate-mapping package="component">

<composite-id name="componentpk"

class="ComponentPK"

unsaved-value="any">

<key-property name="name"

column="name"

type="java.lang.String"/>

<key-property name="sex"

column="sex"

type="java.lang.String"/>

<key-many-to-one name="user" class="User" column="userid" access="field" foreign-key="id"></key-many-to-one>

</composite-id>

</class>

</hibernate-mapping>

修改测试代码：

public static void main(String[] args) {

Configuration cfg=new Configuration();

cfg.configure();

SessionFactory sf=cfg.buildSessionFactory();

Session session=sf.openSession();

Transaction t=session.beginTransaction();

User user=(User)session.get(User.class, "11111");

ComponentPK pk=new ComponentPK();

pk.setName("1");

pk.setSex("3");

pk.setUser(user);

Component component=new Component();

component.setComponentpk(pk);

component.setDescription("12");

session.save(component);

t.commit();

System.out.println("success");

}

可以看到数据库结果如下：
User(id为111111)

id	pass
11111	!234

Component的联合主键(name,sex,userid),其中userid已经引用了user表的主键

name	sex	description	userid
1	3	12	11111