Hibernate之one-to-one双向外键关联Annotation

最新推荐文章于 2018-12-18 14:34:25 发布

最新推荐文章于 2018-12-18 14:34:25 发布 · 112 阅读

文章标签：

#java #数据库

本文通过Husband和Wife类展示了Java中使用@OneToOne注解进行实体关系映射的方法，包括如何设置主键和外键，以及生成的SQL语句。

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Husband.java

package com.itmyhome.model; import javax.persistence.Entity; import javax.persistence.FetchType; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.OneToOne; @Entity public class Husband { private int id; private String name; private Wife wife; /* * Id生成策略 mysql默认是auto_crement */ @Id @GeneratedValue public int getId() { return id; } public void setId(int id) { this.id = id; } /* * OneToOne * JoinColumn用来指定生成的外键名字 */ @OneToOne(fetch=FetchType.LAZY) @JoinColumn(name="wifeId") public Wife getWife() { return wife; } public void setWife(Wife wife) { this.wife = wife; } public String getName() { return name; } public void setName(String name) { this.name = name; } }

Wife.java

package com.itmyhome.model; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.OneToOne; @Entity public class Wife { private int id; private String name; private Husband husband; @Id @GeneratedValue public int getId() { return id; } public void setId(int id) { this.id = id; } /* * 凡是双向必设mappedBy * 如果不设mappedBy 双方都会加外键约束 */ @OneToOne(mappedBy="wife") @JoinColumn(name="husbandId") public Husband getHusband() { return husband; } public void setHusband(Husband husband) { this.husband = husband; } public String getName() { return name; } public void setName(String name) { this.name = name; } }

hibernate生成的sql如下：

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

create table Wife ( id integer not null auto_increment, name varchar(255), primary key (id) ) alter table Husband add index FKAEEA401B78A8164D (wifeId), add constraint FKAEEA401B78A8164D foreign key (wifeId) references Wife (id)