hibernate复合主键
来源:互联网 发布:hidpi canvas.js下载 编辑:程序博客网 时间:2024/05/16 07:34
Hibernate的复合主键映射
原创作品,允许转载,转载时请务必以超链接形式标明文章原始出处 、作者信息和本声明。否则将追究法律责任。http://yangfei520.blog.51cto.com/1041581/310555
1>.学过hibernate的都知道用<id>来配置主键生成策略,显然,它只能配置主键是单列的表,对于联合主键的情况<id>就无能为力了。今天翻到个复合主键映射的资料,觉得还是有一定价值的,就写了下来,以备后用。
2>.hibernate处理复合主键映射是基于这样一种做法:把目标类中所有主键关联属性抽出来,单独写成一个类(我暂且叫它主键类),目标类就只需持有主键类对象,而不必再包含各个主键属性;在映射文件中使用<composite-id>标签来配置主键对象并指出关联属性,普通属性照常配置;hibernate只会创建一张表在,并且把主键设置为主键类各属性的联合主键,存储和加载数据时,会自然的把关联对象各属性跟表中的主键字段对应起来。在这个操作过程中,它要求主键类必须是序列化的,并且要覆盖equals方法,最好覆盖hashCode方法。(我试验过了,不覆盖equals和hashCode,结果没有出现任何问题,而且从输出的sql语句看,也没有影响数据库操作,不知道它是否还有更深的含义?还希望高手给指点下)
3>.例子。一个规模较大公司的部门表(hibernate_dept_compositePK),由所在区域(area),部门名(name),本部门人数(empCount),组建时间(birthday)等字段组成,我们使用所在区域和部门名做联合主键:
2>.hibernate处理复合主键映射是基于这样一种做法:把目标类中所有主键关联属性抽出来,单独写成一个类(我暂且叫它主键类),目标类就只需持有主键类对象,而不必再包含各个主键属性;在映射文件中使用<composite-id>标签来配置主键对象并指出关联属性,普通属性照常配置;hibernate只会创建一张表在,并且把主键设置为主键类各属性的联合主键,存储和加载数据时,会自然的把关联对象各属性跟表中的主键字段对应起来。在这个操作过程中,它要求主键类必须是序列化的,并且要覆盖equals方法,最好覆盖hashCode方法。(我试验过了,不覆盖equals和hashCode,结果没有出现任何问题,而且从输出的sql语句看,也没有影响数据库操作,不知道它是否还有更深的含义?还希望高手给指点下)
3>.例子。一个规模较大公司的部门表(hibernate_dept_compositePK),由所在区域(area),部门名(name),本部门人数(empCount),组建时间(birthday)等字段组成,我们使用所在区域和部门名做联合主键:
1.目标类:Department.java
public class Department {
/** 把主键关联属性抽象出来单独写成一个类 */
//private String area;
//private String name;
/**把主键类对象作为成员变量*/
private DepartmentPK departmentPK;
private int empCount;
private Date birthday;
// public String getArea() {
// return area;
// }
//
// public void setArea(String area) {
// this.area = area;
// }
//
// public String getName() {
// return name;
// }
//
// public void setName(String name) {
// this.name = name;
// }
public int getEmpCount() {
return empCount;
}
public void setEmpCount(int empCount) {
this.empCount = empCount;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public DepartmentPK getDepartmentPK() {
return departmentPK;
}
public void setDepartmentPK(DepartmentPK departmentPK) {
this.departmentPK = departmentPK;
}
}
/** 把主键关联属性抽象出来单独写成一个类 */
//private String area;
//private String name;
/**把主键类对象作为成员变量*/
private DepartmentPK departmentPK;
private int empCount;
private Date birthday;
// public String getArea() {
// return area;
// }
//
// public void setArea(String area) {
// this.area = area;
// }
//
// public String getName() {
// return name;
// }
//
// public void setName(String name) {
// this.name = name;
// }
public int getEmpCount() {
return empCount;
}
public void setEmpCount(int empCount) {
this.empCount = empCount;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public DepartmentPK getDepartmentPK() {
return departmentPK;
}
public void setDepartmentPK(DepartmentPK departmentPK) {
this.departmentPK = departmentPK;
}
}
2.主键类:DepartmentPK.java
public class DepartmentPKimplements Serializable {
private staticfinal long serialVersionUID = -288002855915204255L;
private String area;
private String name;
/**
* 覆盖hashCode方法(根据area和name判断)
*/
//@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((area == null) ? 0 : area.hashCode());
result = prime * result + ((name == null) ? 0 : name.hashCode());
return result;
}
/**
* 覆盖equals(根据area和name判断)
*/
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
final DepartmentPK other = (DepartmentPK) obj;
if (area == null) {
if (other.area != null)
return false;
} else if (!area.equals(other.area))
return false;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
return true;
}
public String getArea() {
return area;
}
public void setArea(String area) {
this.area = area;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
private staticfinal long serialVersionUID = -288002855915204255L;
private String area;
private String name;
/**
* 覆盖hashCode方法(根据area和name判断)
*/
//@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((area == null) ? 0 : area.hashCode());
result = prime * result + ((name == null) ? 0 : name.hashCode());
return result;
}
/**
* 覆盖equals(根据area和name判断)
*/
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
final DepartmentPK other = (DepartmentPK) obj;
if (area == null) {
if (other.area != null)
return false;
} else if (!area.equals(other.area))
return false;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
return true;
}
public String getArea() {
return area;
}
public void setArea(String area) {
this.area = area;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
3.映射文件Department.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="com.yangfei.hibernate.compositePk.entity.Department"table="hibernate_dept_compositePK">
<!-- 联合主键 -->
<!-- name指的是主键对象属性 -->
<composite-idname="departmentPK">
<!-- 这里是主键关联属性 -->
<key-propertyname="area"/>
<key-propertyname="name"/>
</composite-id>
<!-- 其它属性 -->
<propertyname="empCount"length="4" />
<propertyname="birthday"type="date"/>
</class>
</hibernate-mapping>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="com.yangfei.hibernate.compositePk.entity.Department"table="hibernate_dept_compositePK">
<!-- 联合主键 -->
<!-- name指的是主键对象属性 -->
<composite-idname="departmentPK">
<!-- 这里是主键关联属性 -->
<key-propertyname="area"/>
<key-propertyname="name"/>
</composite-id>
<!-- 其它属性 -->
<propertyname="empCount"length="4" />
<propertyname="birthday"type="date"/>
</class>
</hibernate-mapping>
4.hibernate配置文件hibernate.cfg.xml
<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<!-- Generated by MyEclipse Hibernate Tools. -->
<hibernate-configuration>
<session-factory>
<propertyname="dialect">org.hibernate.dialect.Oracle9Dialect</property>
<propertyname="connection.url">jdbc:oracle:thin:@127.0.0.1:1521:orcl10</property>
<propertyname="connection.username">scott</property>
<propertyname="connection.password">yf123</property>
<propertyname="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
<propertyname="hibernate.show_sql">true</property>
<mappingresource="com/yangfei/hibernate/compositePk/entity/Department.hbm.xml"/>
</session-factory>
</hibernate-configuration>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<!-- Generated by MyEclipse Hibernate Tools. -->
<hibernate-configuration>
<session-factory>
<propertyname="dialect">org.hibernate.dialect.Oracle9Dialect</property>
<propertyname="connection.url">jdbc:oracle:thin:@127.0.0.1:1521:orcl10</property>
<propertyname="connection.username">scott</property>
<propertyname="connection.password">yf123</property>
<propertyname="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
<propertyname="hibernate.show_sql">true</property>
<mappingresource="com/yangfei/hibernate/compositePk/entity/Department.hbm.xml"/>
</session-factory>
</hibernate-configuration>
5.测试类:DepartmentTest.java
public class DepartmentTestextends TestCase {
/**
* 测试插入数据
*/
public void save() {
Session session = HibernateUtils.getSession();
Transaction t = session.beginTransaction();
try {
Department dept = new Department();
/** 生成主键对象 */
DepartmentPK deptPK = new DepartmentPK();
deptPK.setArea("北京");
deptPK.setName("研发部");
dept.setDepartmentPK(deptPK);
dept.setEmpCount(100);
dept.setBirthday(new Date());
session.save(dept);
t.commit();
} catch (HibernateException e) {
e.printStackTrace();
t.rollback();
} finally {
HibernateUtils.closeSession(session);
}
}
/**
* 测试加载数据
*/
public void load() {
Session session = HibernateUtils.getSession();
Transaction t = session.beginTransaction();
try {
/** 生成主键对象 */
DepartmentPK deptPK = new DepartmentPK();
deptPK.setArea("北京");
deptPK.setName("研发部");
Department dept=(Department)session.load(Department.class, deptPK);
System.out.println(dept.getDepartmentPK().getArea()+","+dept.getDepartmentPK().getName()+","+dept.getEmpCount()+","+dept.getBirthday());
} catch (HibernateException e) {
e.printStackTrace();
t.rollback();
} finally {
HibernateUtils.closeSession(session);
}
}
/**
* 测试修改数据
*/
public void update() {
Session session = HibernateUtils.getSession();
Transaction t = session.beginTransaction();
try {
/** 生成主键对象 */
DepartmentPK deptPK = new DepartmentPK();
deptPK.setArea("北京");
deptPK.setName("研发部");
Department emp=(Department)session.load(Department.class, deptPK);
System.out.println(emp.getDepartmentPK().getArea()+","+emp.getDepartmentPK().getName()+","+emp.getEmpCount()+","+emp.getBirthday());
emp.setEmpCount(100);
session.saveOrUpdate(emp);
/** 生成主键对象 */
DepartmentPK deptPK2 = new DepartmentPK();
deptPK2.setArea("北京");
deptPK2.setName("研发部");
Department dept=(Department)session.load(Department.class, deptPK2);
System.out.println(dept.getDepartmentPK().getArea()+","+dept.getDepartmentPK().getName()+","+dept.getEmpCount()+","+dept.getBirthday());
t.commit();
} catch (HibernateException e) {
e.printStackTrace();
t.rollback();
} finally {
HibernateUtils.closeSession(session);
}
}
/**
* 测试删除数据
*/
public void delete() {
Session session = HibernateUtils.getSession();
Transaction t = session.beginTransaction();
try {
/** 生成主键对象 */
DepartmentPK deptPK = new DepartmentPK();
deptPK.setArea("北京");
deptPK.setName("研发部");
Department dept=(Department)session.load(Department.class, deptPK);
session.delete(dept);
t.commit();
} catch (HibernateException e) {
e.printStackTrace();
t.rollback();
} finally {
HibernateUtils.closeSession(session);
}
}
}
/**
* 测试插入数据
*/
public void save() {
Session session = HibernateUtils.getSession();
Transaction t = session.beginTransaction();
try {
Department dept = new Department();
/** 生成主键对象 */
DepartmentPK deptPK = new DepartmentPK();
deptPK.setArea("北京");
deptPK.setName("研发部");
dept.setDepartmentPK(deptPK);
dept.setEmpCount(100);
dept.setBirthday(new Date());
session.save(dept);
t.commit();
} catch (HibernateException e) {
e.printStackTrace();
t.rollback();
} finally {
HibernateUtils.closeSession(session);
}
}
/**
* 测试加载数据
*/
public void load() {
Session session = HibernateUtils.getSession();
Transaction t = session.beginTransaction();
try {
/** 生成主键对象 */
DepartmentPK deptPK = new DepartmentPK();
deptPK.setArea("北京");
deptPK.setName("研发部");
Department dept=(Department)session.load(Department.class, deptPK);
System.out.println(dept.getDepartmentPK().getArea()+","+dept.getDepartmentPK().getName()+","+dept.getEmpCount()+","+dept.getBirthday());
} catch (HibernateException e) {
e.printStackTrace();
t.rollback();
} finally {
HibernateUtils.closeSession(session);
}
}
/**
* 测试修改数据
*/
public void update() {
Session session = HibernateUtils.getSession();
Transaction t = session.beginTransaction();
try {
/** 生成主键对象 */
DepartmentPK deptPK = new DepartmentPK();
deptPK.setArea("北京");
deptPK.setName("研发部");
Department emp=(Department)session.load(Department.class, deptPK);
System.out.println(emp.getDepartmentPK().getArea()+","+emp.getDepartmentPK().getName()+","+emp.getEmpCount()+","+emp.getBirthday());
emp.setEmpCount(100);
session.saveOrUpdate(emp);
/** 生成主键对象 */
DepartmentPK deptPK2 = new DepartmentPK();
deptPK2.setArea("北京");
deptPK2.setName("研发部");
Department dept=(Department)session.load(Department.class, deptPK2);
System.out.println(dept.getDepartmentPK().getArea()+","+dept.getDepartmentPK().getName()+","+dept.getEmpCount()+","+dept.getBirthday());
t.commit();
} catch (HibernateException e) {
e.printStackTrace();
t.rollback();
} finally {
HibernateUtils.closeSession(session);
}
}
/**
* 测试删除数据
*/
public void delete() {
Session session = HibernateUtils.getSession();
Transaction t = session.beginTransaction();
try {
/** 生成主键对象 */
DepartmentPK deptPK = new DepartmentPK();
deptPK.setArea("北京");
deptPK.setName("研发部");
Department dept=(Department)session.load(Department.class, deptPK);
session.delete(dept);
t.commit();
} catch (HibernateException e) {
e.printStackTrace();
t.rollback();
} finally {
HibernateUtils.closeSession(session);
}
}
}
4.一般来说,复合主键映射用起来是很复杂的,无论是开发时还是升级时。所以,人们往往宁愿选择增加个主键字段,也不尽量不采用它。
- Hibernate复合主键
- hibernate 复合主键
- hibernate复合主键
- Hibernate复合主键例子
- Hibernate复合主键
- Hibernate复合主键
- Hibernate 复合主键
- hibernate中复合主键
- hibernate复合主键映射
- Hibernate复合主键映射
- Hibernate 使用复合主键
- Hibernate复合主键映射
- hibernate复合主键
- hibernate复合主键代码
- hibernate配置复合主键
- Hibernate复合主键映射
- Hibernate复合主键映射
- Hibernate复合主键映射
- 11g ASM单实例 dbca报错 prcr-1006 crs-0259 prcr-1071
- IPhone中UIView中动画及其属性说明
- MFC的GUI窗口使用Console输出函数printf
- eclipse常用快捷键总结
- 第一次C程序设计上机报告
- hibernate复合主键
- java jdbc 汇总
- jdbc详解(增删改查、事务、存储过程)
- 动态规划之矩阵连乘问题
- 信息图:移动端APP设计指南
- mongodb GridView C#
- 人生如流星
- Jquery操作select
- 打印从0到1000的所有素数