夜光带你走进Hibernate（三）

旧城等待， 2022-02-16 10:41 226阅读 0赞

## 夜光序言： ##

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## 正文： ##

# **6. 联合主键映射** #

夜光：联合主键，

多列共同作为主键~~

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td>夜光：数据库，联合主键：</td> 
 </tr> 
 <tr> 
 <td> -- 联合主键 &nbsp;(hbm: &nbsp;&nbsp;&lt;composite-id&gt;&lt;/composite-id&gt; &nbsp;&nbsp;) CREATE TABLE test( &nbsp;&nbsp;id1 INT, &nbsp;&nbsp;id2 INT, &nbsp;&nbsp;PRIMARY KEY(id1,id2) ); &nbsp; &nbsp; SELECT * FROM test; -- 插入 INSERT INTO test VALUES(1,1); INSERT INTO test VALUES(1,2); &nbsp; INSERT INTO test VALUES(1,2); &nbsp;-- 错误 </td> 
 </tr> 
 </tbody> 
</table>

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:

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td> /** &nbsp;*&nbsp;夜光：联合主键对象, 必须要实现可课序列化标记~~帅气 &nbsp;*/ public&nbsp;class&nbsp;CompositeKeys&nbsp;implements&nbsp;Serializable{ &nbsp; private&nbsp;String name; private&nbsp;String address; &nbsp;&nbsp;&nbsp;.. } </td> 
 </tr> 
 <tr> 
 <td> //&nbsp;夜光：员工 public&nbsp;class&nbsp;Employee { &nbsp; &nbsp;//&nbsp;夜光：名称、地址、部门、年龄 &nbsp; // 联合主键对象 private&nbsp;CompositeKeys keys; private&nbsp;String dept; private&nbsp;Date birth; .. } </td> 
 </tr> 
 <tr> 
 <td>Employee的映射：</td> 
 </tr> 
 <tr> 
 <td> &lt;?xml&nbsp;version="1.0"&nbsp;encoding="UTF-8"?&gt; &lt;!DOCTYPE&nbsp;hibernate-mapping&nbsp;PUBLIC&nbsp; "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"&gt; &nbsp; &lt;hibernate-mapping&nbsp;package="cn.Genius.c_composite"&gt; &lt;class&nbsp;name="Employee" table="t_employee"&gt; &lt;composite-id&nbsp;name="keys"&gt; &lt;key-property&nbsp;name="name"&gt;&lt;/key-property&gt; &lt;key-property&nbsp;name="address"&gt;&lt;/key-property&gt; &lt;/composite-id&gt; &nbsp; &lt;property&nbsp;name="dept" length="50"&gt;&lt;/property&gt; &lt;property&nbsp;name="birth" type="date"&gt;&lt;/property&gt; &lt;/class&gt; &nbsp; &nbsp; &lt;/hibernate-mapping&gt; </td> 
 </tr> 
 <tr> 
 <td>&nbsp;</td> 
 </tr> 
 <tr> 
 <td>测试</td> 
 </tr> 
 <tr> 
 <td> public&nbsp;class&nbsp;App { private&nbsp;static&nbsp;SessionFactory sf; static&nbsp;{ sf&nbsp;= new&nbsp;Configuration().configure().buildSessionFactory(); } &nbsp; @Test public&nbsp;void&nbsp;testSave() throws&nbsp;Exception { Session session = sf.openSession(); session.beginTransaction(); &nbsp; // 联合主键对象 CompositeKeys keys = new&nbsp;CompositeKeys(); keys.setName("Genius"); keys.setAddress("夜光之屋..."); &nbsp; // 对象 Employee emp = new&nbsp;Employee(); emp.setKeys(keys); emp.setDept("科技-研发部"); emp.setBirth(new&nbsp;Date()); &nbsp; // 保存 session.save(emp); &nbsp; &nbsp; session.getTransaction().commit(); session.close(); &nbsp; } &nbsp; @Test public&nbsp;void&nbsp;testGet() throws&nbsp;Exception { Session session = sf.openSession(); session.beginTransaction(); &nbsp; // 联合主键对象 CompositeKeys keys = new&nbsp;CompositeKeys(); keys.setName("Genius"); keys.setAddress("夜光之屋..."); &nbsp; 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()); &nbsp; session.getTransaction().commit(); session.close(); &nbsp; } } </td> 
 </tr> 
 </tbody> 
</table>

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MTk4NzcwNg_size_16_color_FFFFFF_t_70 1][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MTk4NzcwNg_size_16_color_FFFFFF_t_70 2][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MTk4NzcwNg_size_16_color_FFFFFF_t_70 3][]

本文原文地址：[https://blog.csdn.net/weixin\_41987706/article/details/89235885][https_blog.csdn.net_weixin_41987706_article_details_89235885]

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[https_blog.csdn.net_weixin_41987706_article_details_89235885]: https://blog.csdn.net/weixin_41987706/article/details/89235885