Hibernate annotation 一對一關係共享主鍵配置
作者 武漢科技大學 周劍華
引言
在這個例子中.分爲學生基本信息表(student_basic)和學生詳細信息表(student_detail).兩個表共享主鍵.利用hibernate annotation 的@one2one映射.爲了共享主鍵,需要用到hibernate的@PrimaryKeyJoinColumn來完成.
數據庫schema
第一. 數據庫的關係圖
(該文章書寫時在word中完成.但是由於javaeye的編輯目前不支持圖片拷貝.暫時無法顯示該圖片.該圖片是一個ER圖.描述student_basic和student_detail的關係)
第二.ddl語句
create table student_detail
(
student_id int not null,
home_address varchar(100),
home_phome varchar(13)
);
/*==============================================================*/
/* Table: studnet_basic */
/*==============================================================*/
create table studnet_basic
(
student_id int not null,
studnet_name varchar(20),
sex varchar(10),
primary key (student_id)
);
alter table student_detail add constraint FK_R_Student_basic_detail foreign key (student_id)
references studnet_basic (student_id) on delete restrict on update restrict;
實體類配置
第一. StudentBasic類配置
package org.jenfer.interview.ch07.entity;
import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity(name="StudentBasic")
@Table(name="student_basic")
public class StudentBasic implements Serializable{
private static final long serialVersionUID = 691350277643811847L;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="student_id")
private Integer studentId;
@Column(length=10)
private String studentName;
@Column(length=10)
private String sex;
public StudentBasic() {
}
public Integer getStudentId() {
return studentId;
}
public void setStudentId(Integer studentId) {
this.studentId = studentId;
}
public String getStudentName() {
return studentName;
}
public void setStudentName(String studentName) {
this.studentName = studentName;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
}
第二 . StudentDetail配置
package org.jenfer.interview.ch07.entity;
import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;
import javax.persistence.Table;
import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.Parameter;
@Entity(name="StudentDetail")
@Table(name="student_detail")
public class StudentDetail implements Serializable{
private static final long serialVersionUID = 2038888147029653370L;
@Id
@Column(name="student_id")
@GeneratedValue(generator="foreigner")
@GenericGenerator(name="foreigner",strategy="foreign",parameters={
@Parameter(name = "property",value="studentBasic")
})
private Integer stuId;
@OneToOne
@PrimaryKeyJoinColumn
private StudentBasic studentBasic;
@Column(length=50)
private String homeAddress;
@Column(length=100)
private String homePhomeNumber;
public StudentDetail() {
}
public StudentBasic getStudentBasic() {
return studentBasic;
}
public void setStudentBasic(StudentBasic studentBasic) {
this.studentBasic = studentBasic;
}
public String getHomeAddress() {
return homeAddress;
}
public void setHomeAddress(String homeAddress) {
this.homeAddress = homeAddress;
}
public String getHomePhomeNumber() {
return homePhomeNumber;
}
public void setHomePhomeNumber(String homePhomeNumber) {
this.homePhomeNumber = homePhomeNumber;
}
public Integer getStuId() {
return stuId;
}
public void setStuId(Integer stuId) {
this.stuId = stuId;
}
}
小結
由於JPA沒有定義怎麼共享主鍵的方法.所以必須得藉助hibernate的屬性來設置.在
@Id
@Column(name="stu_id")
@GeneratedValue(generator="foreigner")
@GenericGenerator(name="foreigner",strategy="foreign",parameters={
@Parameter(name = "property",value="studentBasic")
})
語句塊中, @Parameter(name = "property", value="studentBasic")屬性指出,從類StudentDetail的主鍵要共享studentBasic屬性的主鍵值.