夜光带你走进Hibernate（三）
夜光序言：
取万家之众长，自成一家，取长补短，相互兼并，兼容并蓄，海纳百川。
正文：
6. 联合主键映射
夜光：联合主键，
多列共同作为主键~~
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夜光：数据库，联合主键： |
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-- 联合主键 (hbm: <composite-id></composite-id> ) CREATE TABLE test( id1 INT, id2 INT, PRIMARY KEY(id1,id2) );
SELECT * FROM test; -- 插入 INSERT INTO test VALUES(1,1); INSERT INTO test VALUES(1,2); INSERT INTO test VALUES(1,2); -- 错误 |
需求：
保存员工信息: 名称、地址、部门、年龄
(联合主键：名称、地址)
设计javabean：
写映射：
App:
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/** * 夜光：联合主键对象, 必须要实现可课序列化标记~~帅气 */ public class CompositeKeys implements Serializable{
private String name; private String address; .. } |
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// 夜光：员工 public class Employee {
// 夜光：名称、地址、部门、年龄
// 联合主键对象 private CompositeKeys keys; private String dept; private Date birth; .. }
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Employee的映射： |
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<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="cn.Genius.c_composite"> <class name="Employee" table="t_employee"> <composite-id name="keys"> <key-property name="name"></key-property> <key-property name="address"></key-property> </composite-id>
<property name="dept" length="50"></property> <property name="birth" type="date"></property> </class>
</hibernate-mapping>
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测试 |
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public class App { private static SessionFactory sf; static { sf = new Configuration().configure().buildSessionFactory(); }
@Test public void testSave() throws Exception { Session session = sf.openSession(); session.beginTransaction();
// 联合主键对象 CompositeKeys keys = new CompositeKeys(); keys.setName("Genius"); keys.setAddress("夜光之屋...");
// 对象 Employee emp = new Employee(); emp.setKeys(keys); emp.setDept("科技-研发部"); emp.setBirth(new Date());
// 保存 session.save(emp);
session.getTransaction().commit(); session.close();
}
@Test public void testGet() throws Exception { Session session = sf.openSession(); session.beginTransaction();
// 联合主键对象 CompositeKeys keys = new CompositeKeys(); keys.setName("Genius"); keys.setAddress("夜光之屋...");
Employee employee = (Employee) session.get(Employee.class, keys); System.out.println(employee.getKeys().getName()); System.out.println(employee.getKeys().getAddress()); System.out.println(employee.getDept()); System.out.println(employee.getBirth());
session.getTransaction().commit(); session.close();
} }
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