分别创建user,farm,user_general三张表

create table user( uuid bigint not null auto_increment, name varchar(100), age int not null, province varchar(100), city varchar(100), street varchar(100), constraint pk_user primary key(uuid))charset=utf8 ENGINE=InnoDB;create table user_general(uuid bigint not null,realname varchar(10),gender varchar(10),birthday int,height int,weight int, constraint pk_user_general primary key(uuid), constraint fk_user_general foreign key(uuid) references user(uuid))charset=utf8 ENGINE=InnoDB;create table farm(uuid bigint not null auto_increment,user_id bigint,name varchar(10),constraint pk_farm primary key(uuid),constraint fk_farm foreign key(user_id) references user(uuid))charset=utf8 ENGINE=InnoDB;

单向关联：

1.多对一映射(many to one)：

该标签在持久化类中属于多的一方配置；例如本例中farm即为多的一方。

 重点是这段配置:

 <many-to-one name="user" class="org.hibernate.tutorials.domain.User" column="user_id" cascade="save-update"/>

 其中column对应表中的外键(另一张表的主键)，cascade设置为save-update后即可实现向数据库中级联修改

 farm.hbm.xml配置:

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Farm对应的实体类:　

public class Farm implements Serializable{        private int uuid;        private String name;        private User user;//农场所属用户    /**     * @return the uuid     */    public int getUuid() {        return uuid;    }    /**     * @param uuid the uuid to set     */    public void setUuid(int uuid) {        this.uuid = uuid;    }    /**     * @return the name     */    public String getName() {        return name;    }    /**     * @param name the name to set     */    public void setName(String name) {        this.name = name;    }    /**     * @return the user     */    public User getUser() {        return user;    }    /**     * @param user the user to set     */    public void setUser(User user) {        this.user = user;    }    /* (non-Javadoc)     * @see java.lang.Object#toString()     */    @Override    public String toString() {        return "Farm [uuid=" + uuid + ", name=" + name + "]";    }

测试代码:   

1     Session session = HibernateUtil.getSessionFactory().getCurrentSession(); 2          3         User user = new User(); 4         user.setName("lucy"); 5          6         Farm farm=new Farm(); 7         farm.setName("test3"); 8         farm.setUser(user); 9         10         Farm farm1=new Farm();11         farm1.setName("test4");12         farm1.setUser(user);13         14         session.beginTransaction();15         session.save(farm);16         session.save(farm1);17         session.getTransaction().commit();

2.一对一映射(分为2种情况：唯一外键和主键关联)

2.1：唯一外键：用的标签仍为many-to-one 区别是需要加unique="true"属性表示唯一映射，具体案例

2.2主键关联映射:(一个字段同时是主键和外键(user和user_general))

 <one-to-one name="user" class="org.hibernate.tutorials.domain.User" constrained="true"/>  constrained="true"指明该类(UserGeneral)和关联的类(User)对应的表，通过外键引用对主键约束

UserGeneral.hbm.xml 配置 

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  测试代码: 

1     Session session = HibernateUtil.getSessionFactory().getCurrentSession(); 2          3         User user = new User(); 4         user.setName("rrrrr"); 5          6         UserGeneral ge=new UserGeneral(); 7         ge.setUser(user); 8         ge.setRealname("cccccc"); 9         10         session.beginTransaction();11         session.save(ge);12         session.getTransaction().commit();

 

 

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