Hibernate @OneToOne -- 2

最新推荐文章于 2022-04-21 22:36:29 发布

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本文详细解释了在Java中如何使用@OneToOne注解来实现一对一的关系，并通过创建两个类（classPerson和IDCard）和两张表（idcard和person）来展示这种关系的实现过程。重点在于理解mappedBy属性的作用，它指示了双向一对一关系中由哪个实体拥有子实体的主键。

class Person

@OneToOne
public IDCard getIdcard() {
  return idcard;
}

class IDCard

@OneToOne(mappedBy="idcard") 
public Person getPerson() {
  return person;
}

table

CREATE TABLE `idcard` (
  `id` varchar(32) NOT NULL,
  `createDate` datetime DEFAULT NULL,
  `modifyDate` datetime DEFAULT NULL,
  `bureau` varchar(255) DEFAULT NULL,
  `number` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE `person` (
  `id` varchar(32) NOT NULL,
  `createDate` datetime DEFAULT NULL,
  `modifyDate` datetime DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  `name` varchar(255) DEFAULT NULL,
  `idcard_id` varchar(32) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `FKC4E39B5538F44A9E` (`idcard_id`),
  CONSTRAINT `FKC4E39B5538F44A9E` FOREIGN KEY (`idcard_id`) REFERENCES `idcard` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

**mappedBy indicates that a bidirectional one-to-one relationship is owned by the named entity.
**The owning entity contains the primary key of the subordinate entity.