Rhythmk 学习 Hibernate 08 - Hibernate annotation 关联关系注解

浏览数：29 / 时间：2015年06月20日

1、一对一 (One to One)
共三种情况:
1.1 主键共享
1.2 外键共享

1.3 中间表关联

1.1 code:

@Entity
public class article {
    @Id
    @GeneratedValue
   public 
Integer getArticleId() {
        return 
articleId;
    }
    .....
    @OneToOne(cascade=CascadeType.ALL)
    @PrimaryKeyJoinColumn
        public 
articleContent getContent() {
        return 
content;
    }
    ......
}

@Entity
public class articleContent  {
     
    @Id
    @GeneratedValue
    public 
Integer getcId() {
        return 
cId;
    }
    ....
}

　　执行保存生成两张无外键的独立表

1.2 code:

@Entity
public class article {
     
    @OneToOne(cascade=CascadeType.ALL)
    @JoinColumn(name="cid_fk")
        public 
articleContent getContent() {
        return 
content;
    }
     
}
 
@Entity
public 
class articleContent  {
     
    @OneToOne(mappedBy="articleContent")
    public 
article ArticleEntity;
}

　　执行保存，生成两张表，同时article生成一个cid_fk字段关联 articleContent主键ID

1.3 code:

@Entity
public class article {
    @Id
    @GeneratedValue
   public 
Integer getArticleId() {
        return 
articleId;
    }
 
    @OneToOne(cascade=CascadeType.ALL)
    @JoinTable(name="article_content",
          joinColumns=@JoinColumn(name="aid"),
          inverseJoinColumns=@JoinColumn(name="aid_fk"))
        public 
articleContent getContent() {
        return 
content;
    }
    ......
}

　　生成三张表分别为：article，article_content，articlecontent 其中 article_content 分别生成两个外键具体参考等价建表语句：

CREATE TABLE `article_content` (
  `aid_fk` int(11) DEFAULT 
NULL,
  `aid` int(11) NOT 
NULL,
  PRIMARY 
KEY (`aid`),
  KEY 
`FK_7pgn2vn8r1lpswmh5v2ix667s` (`aid_fk`),
  CONSTRAINT 
`FK_ebfc4cs1sishg6u8kwpvgqqj9` FOREIGN 
KEY (`aid`) REFERENCES 
`article` (`articleId`),
  CONSTRAINT 
`FK_7pgn2vn8r1lpswmh5v2ix667s` FOREIGN 
KEY (`aid_fk`) REFERENCES 
`articlecontent` (`cId`)
) ENGINE=InnoDB DEFAULT 
CHARSET=utf8;