public class Company {private Integer id;private String name;private Address address;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Address getAddress() {return address;}public void setAddress(Address address) {this.address = address;}} public class Address {private Integer id;private String name;private Company company;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Company getCompany() {return company;}public void setCompany(Company company) {this.company = company;}}

        Company.hbm.xml<hibernate-mapping ><class name="com.cad.domain.Company" table="company"><id name="id" column="id"><generator class="native"></generator></id><property name="name" column="name"></property> <!--column指定外键，unique指定外键唯一约束，设为true，就可以表达Company和Address对象之间的一对一关联--><many-to-one name="address" class="com.cad.domain.Address" column="aid" unique="true"></many-to-one></class></hibernate-mapping>   Address.hbm.xml <hibernate-mapping ><class name="com.cad.domain.Address" table="address"><id name="id" column="id"><generator class="native"></generator></id><property name="name" column="name"></property> <!--property-ref属性指定通过从Company的address属性来查找自己--><one-to-one name="Company" class="com.cad.domain.Company" property-ref="address"></one-to-one></class></hibernate-mapping>

                 public class Demo {private Session session;@Testpublic void test() {//读取配置文件Configuration conf=new Configuration().configure();//根据配置创建factorySessionFactory sessionfactory=conf.buildSessionFactory();session = sessionfactory.openSession(); Transaction ts=session.beginTransaction();Company c=new Company();c.setName("百度");Address a=new Address();a.setName("深圳");c.setAddress(a);a.setCompany(c);session.save(a);session.save(c); ts.commit();session.close();sessionfactory.close();}}默认情况下，一对一关联采用迫切左外连接检索策略。

    实体类不变，我们编写一下配置文件address的表的id字段既是主键又是外键.编写配置文件Company.hbm.xml <hibernate-mapping ><class name="com.cad.domain.Company" table="company"><id name="id" column="id"><generator class="native"></generator></id><property name="name" column="name"></property><one-to-one name="address" class="com.cad.domain.Address" ></one-to-one></class></hibernate-mapping> Address.hbm.xml <hibernate-mapping ><class name="com.cad.domain.Address" table="address"><id name="id" column="id"><!--必须使用foreign标识符生成策略，还要指定哪个对象共享OID--><generator class="foreign"><param name="property">company</param></generator></id><property name="name" column="name"></property><!--constrained属性设为true，说明主键同时作为外键--><one-to-one name="company" class="com.cad.domain.Company" constrained="true"></one-to-one></class></hibernate-mapping>