多对一单向关联（annotation&xml）

数据库：两张表，在多方加键

一、编写一方实体类

package org.hibernate.tutorial.domain;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
@Entity
public class Group {
	private int id;
	private String name;
	@Id
	@GeneratedValue
	public int getId() {
		return id;
	}
	public String getName() {
		return name;
	}
	public void setId(int id) {
		this.id = id;
	}
	public void setName(String name) {
		this.name = name;
	}
}

二、编写多方实体类

package org.hibernate.tutorial.domain;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;


@Entity
public class User {
	private int id;
	private String name;
	private Group group;
	@Id
	@GeneratedValue
	public int getId() {
		return id;
	}
	@ManyToOne
    @JoinColumn(name="GroupID")   
	public Group getGroup() {
		return group;
	}
	public void setGroup(Group group) {
		this.group = group;
	}
	public String getName() {
		return name;
	}
	public void setId(int id) {
		this.id = id;
	}
	public void setName(String name) {
		this.name = name;
	}
	
}

在多方加一方外键，即属性，再定义@ManyToOne即可

三、在hibernate.cfg.xml映射配置

<mapping class="org.hibernate.tutorial.domain.Group"/>
		<mapping class="org.hibernate.tutorial.domain.User"/>

四、测试代码

public class OneToOneORMappingTest {
	public static void main(String[] args) {
		new SchemaExport(new AnnotationConfiguration().configure("/hibernate.cfg.xml")).create(true, false);
	}
}

五、测试结果

    create table Group (
        id integer not null auto_increment,
        name varchar(255),
        primary key (id)
    )

    create table User (
        id integer not null auto_increment,
        name varchar(255),
        GroupID integer,
        primary key (id)
    )

    alter table User 
        add index FK_d3xpiqkj77d392pew07ptibhp (GroupID), 
        add constraint FK_d3xpiqkj77d392pew07ptibhp 
        foreign key (GroupID) 
        references Group (id)

xml方式：
一。编写实体类如上
二。配置一方Group.hbm.xml

<?xml version="1.0"?> 
<!DOCTYPE hibernate-mapping PUBLIC 
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN" 
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> 

<hibernate-mapping package="org.hibernate.tutorial.domain"> 

    <class name="Group" table="Group"> 
        <id name="id" column="group_Id"> 
            <generator class="native"/> 
        </id> 
        <property name="name"></property>
    </class> 

</hibernate-mapping> 

三。配置多方User.hbm.xml

<?xml version="1.0"?> 
<!DOCTYPE hibernate-mapping PUBLIC 
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN" 
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> 

<hibernate-mapping package="org.hibernate.tutorial.domain"> 

    <class name="User" table="User"> 
        <id name="id" column="User_ID"> 
            <generator class="native"/> 
        </id> 
        <property name="name"></property>
        <many-to-one name="group" column="groupId"></many-to-one> 
    </class> 

</hibernate-mapping> 

配置多方"属性group"对应列

四。测试如上