Hibernate注解：一对一主键关联

情形：两个表，my_site和my_site_company，通过主键site_id唯一关联。my_site的主键是自动增加，my_site_company的主键依赖于my_site。

#
# Source for table my_site
#

DROP TABLE IF EXISTS `my_site`;
CREATE TABLE `my_site` (
  `site_id` int(11) NOT NULL AUTO_INCREMENT,
  `site_name` varchar(100) DEFAULT NULL COMMENT ‘站点名称‘,
  `short_name` varchar(100) DEFAULT NULL COMMENT ‘简短名称‘,
  PRIMARY KEY (`site_id`)
) ENGINE=MyISAM AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;

#
# Source for table my_site_company
#

DROP TABLE IF EXISTS `my_site_company`;
CREATE TABLE `my_site_company` (
  `site_id` int(11) NOT NULL DEFAULT ‘0‘,
  `name` varchar(255) NOT NULL COMMENT ‘公司名称‘,
  `scale` varchar(255) DEFAULT NULL COMMENT ‘公司规模‘,
  `industry` varchar(1000) DEFAULT NULL COMMENT ‘公司行业‘,
  `contact` varchar(500) DEFAULT NULL COMMENT ‘联系方式‘,
  `address` varchar(500) DEFAULT NULL COMMENT ‘公司地址‘,
  PRIMARY KEY (`site_id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

Site.java：

@Entity
@Table(name = "my_site")
@SuppressWarnings("serial")
public class Site implements Serializable
{ 

    // Site的主键是自动递增
    @Id
    @GeneratedValue
    @Column(name = "site_id")
    private Integer siteId;

    @Column(name = "site_name")
    private String siteName;

    @Column(name = "short_name")
    private String shortName;

    // Site通过主键一对一关联到Company,
    // 在主键自动递增的对象这边写
    @OneToOne(cascade = CascadeType.ALL)
    @PrimaryKeyJoinColumn
    private Company company;
}

Company.java：

@Entity
@Table(name = "my_site_company")
@SuppressWarnings("serial")
public class Company implements Serializable
{
    // Company的主键来源于site的主键
    @Id
    @Column(name = "site_id")
    @GenericGenerator(name = "pkGenerator",
        strategy = "foreign" ,
        parameters = {@Parameter(name = "property", value = "site")})
    @GeneratedValue(generator = "pkGenerator")
    private Integer siteId;

    @Column
    private String name;

    @Column
    private String scale;

    @Column
    private String industry;

    @Column
    private String address;

    @Column
    private String contact;

    @OneToOne(cascade = CascadeType.ALL,
             mappedBy = "company")
    private Site site;
}

CompanyController.java：

public class CompanyController extends SimpleController
{
    @Autowired
    SiteDao siteDao;

    @Autowired
    CompanyDao companyDao;

    @RequestMapping
    public String indexAction(Model model,
            HttpServletRequest request) throws Exception
    {
        Site site = siteDao.fetchOne(1);
        Company company = site.getCompany();
        if (company == null)
            company = new Company();

        if (request.getMethod() != "POST")
        {
            model.addAttribute("entity", company);
            return redirectDefaultView();
        }

        RequestUtils.copyBeanProperties(company);
        company.setSite(site);
        site.setCompany(company);
        companyDao.update(company);

        return redirectIndex(SUCCESS_SAVE);
    }

}