Hibernate注解：一对多外键关联

浏览数：28 / 时间：2015年06月20日

情形：两个表，cms_mode是主表，cms_model_field是子表，cms_model_field的model_id字段关联到cms_model的主键。

#
# Source for table cms_model
#

DROP TABLE IF EXISTS `cms_model`;
CREATE TABLE `cms_model` (
  `model_id` int(11) NOT NULL,
  `name` varchar(50) NOT NULL DEFAULT ‘‘,
  `title` varchar(100) NOT NULL DEFAULT ‘‘ COMMENT ‘名称‘,
) ENGINE=MyISAM DEFAULT CHARSET=utf8 ROW_FORMAT=COMPACT COMMENT=‘CMS模型表‘;

#
# Source for table cms_model_field
#

DROP TABLE IF EXISTS `cms_model_field`;
CREATE TABLE `cms_model_field` (
  `field_id` int(11) NOT NULL AUTO_INCREMENT,
  `model_id` int(11) NOT NULL DEFAULT ‘0‘ COMMENT ‘模型ID‘,
  `name` varchar(50) DEFAULT NULL COMMENT ‘名称‘,
  `title` varchar(250) NOT NULL DEFAULT ‘‘ COMMENT ‘标题‘,
  `priority` int(11) NOT NULL DEFAULT ‘0‘ COMMENT ‘权重‘,
  `data_type` char(1) NOT NULL DEFAULT ‘1‘ COMMENT ‘数据类型(S-字符,N-数值,D-日期,T-备注)‘,
  `is_reserved` tinyint(1) NOT NULL DEFAULT ‘0‘ COMMENT ‘是否保留‘,
  PRIMARY KEY (`field_id`)
) ENGINE=MyISAM AUTO_INCREMENT=4 DEFAULT CHARSET=utf8 COMMENT=‘CMS模型字段表‘;;

CmsModel.java：

@Entity
@Table(name = "cms_model")
@SuppressWarnings("serial")
public class CmsModel implements Serializable
{ 
    @Id
    @GeneratedValue
    @Column(name = "model_id")
    private Integer id;
    
    @Column(name = "name")
    private String name;
    
    @Column(name = "title")
    private String title;
    
    @OneToMany(mappedBy = "model", 
            fetch = FetchType.LAZY)
    private List<CmsModelField> fieldList;
}

CmsModelField.java：

@Entity
@Table(name = "cms_model_field")
@SuppressWarnings("serial")
public class CmsModelField implements Serializable
{ 
    @Id
    @GeneratedValue
    @Column(name = "field_id")
    private Integer id;
    
    @Column(name = "name")
    private String name;
    
    @Column(name = "title")
    private String title;
    
    @Column(name = "data_type")
    private String dataType;
    
    @Column(name = "priority")
    private Integer priority;
    
    @Column(name = "is_reserved")
    private Boolean reserved;
    
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "model_id")
    private CmsModel model;
}

@OneToMany Default: FetchType.LAZY默认是延迟抓取，不需要左联接。如果是FetchType.EAGER即时抓取，就会是左联接查询。
@ManyToOne Default: FetchType.EAGER默认是即时抓取，做连接。如果fetch=FetchType.LAZY不是左联接，在需要One的时候直接select。

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Hibernate注解：一对多外键关联