ORM概念 O, Object 对象R， Realtion 关系 (关系型数据库: MySQL, Oracle…)M，Mapping 映射ORM, 对象关系映射！ORM, 解决什么问题？ 存储： 能否把对象的数据直接保存到数据库？ 获取： 能否直接从数据库拿到一个对象？想做到上面2点，必须要有映射！总结：
<code>O, Object 对象
R， Realtion 关系 (关系型数据库: MySQL, Oracle…)
M，Mapping 映射
ORM, 对象关系映射！
ORM, 解决什么问题？
存储： 能否把对象的数据直接保存到数据库？
获取： 能否直接从数据库拿到一个对象？
想做到上面2点，必须要有映射！
总结：
Hibernate与ORM的关系？
Hibernate是ORM的实现！
</code><code>搭建一个Hibernate环境，开发步骤：
1. 下载源码
版本：hibernate-distribution-3.6.0.Final
2. 引入jar文件
hibernate3.jar核心 + required 必须引入的(6个) + jpa 目录 + 数据库驱动包
3. 写对象以及对象的映射
Employee.java 对象
Employee.hbm.xml 对象的映射 (映射文件)
4. src/hibernate.cfg.xml 主配置文件
数据库连接配置
加载所用的映射(*.hbm.xml)
5. App.java 测试
</code>对象 Employee.java
<code class=" hljs cs"><span class="hljs-comment">//一、 对象</span>
<span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> Employee {
<span class="hljs-keyword">private</span> <span class="hljs-keyword">int</span> empId;
<span class="hljs-keyword">private</span> String empName;
<span class="hljs-keyword">private</span> Date workDate;
}
</code>对象的映射 Employee.hbm.xml
<code class=" hljs xml"><span class="hljs-pi"><?xml version="1.0"?></span>
<span class="hljs-doctype"><!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"></span>
<span class="hljs-tag"><<span class="hljs-title">hibernate-mapping</span> <span class="hljs-attribute">package</span>=<span class="hljs-value">"cn.itcast.a_hello"</span>></span>
<span class="hljs-tag"><<span class="hljs-title">class</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"Employee"</span> <span class="hljs-attribute">table</span>=<span class="hljs-value">"employee"</span>></span>
<span class="hljs-comment"><!-- 主键 ，映射--></span>
<span class="hljs-tag"><<span class="hljs-title">id</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"empId"</span> <span class="hljs-attribute">column</span>=<span class="hljs-value">"id"</span>></span>
<span class="hljs-tag"><<span class="hljs-title">generator</span> <span class="hljs-attribute">class</span>=<span class="hljs-value">"native"</span>/></span>
<span class="hljs-tag"></<span class="hljs-title">id</span>></span>
<span class="hljs-comment"><!-- 非主键，映射 --></span>
<span class="hljs-tag"><<span class="hljs-title">property</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"empName"</span> <span class="hljs-attribute">column</span>=<span class="hljs-value">"empName"</span>></span><span class="hljs-tag"></<span class="hljs-title">property</span>></span>
<span class="hljs-tag"><<span class="hljs-title">property</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"workDate"</span> <span class="hljs-attribute">column</span>=<span class="hljs-value">"workDate"</span>></span><span class="hljs-tag"></<span class="hljs-title">property</span>></span>
<span class="hljs-tag"></<span class="hljs-title">class</span>></span>
<span class="hljs-tag"></<span class="hljs-title">hibernate-mapping</span>></span>
</code>主配置文件 hibernate.cfg.xml
<code class=" hljs xml"><span class="hljs-doctype"><!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"></span>
<span class="hljs-tag"><<span class="hljs-title">hibernate-configuration</span>></span>
<span class="hljs-tag"><<span class="hljs-title">session-factory</span>></span>
<span class="hljs-comment"><!-- 数据库连接配置 --></span>
<span class="hljs-tag"><<span class="hljs-title">property</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"hibernate.connection.driver_class"</span>></span>com.mysql.jdbc.Driver<span class="hljs-tag"></<span class="hljs-title">property</span>></span>
<span class="hljs-tag"><<span class="hljs-title">property</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"hibernate.connection.url"</span>></span>jdbc:mysql:///hib_demo<span class="hljs-tag"></<span class="hljs-title">property</span>></span>
<span class="hljs-tag"><<span class="hljs-title">property</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"hibernate.connection.username"</span>></span>root<span class="hljs-tag"></<span class="hljs-title">property</span>></span>
<span class="hljs-tag"><<span class="hljs-title">property</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"hibernate.connection.password"</span>></span>root<span class="hljs-tag"></<span class="hljs-title">property</span>></span>
<span class="hljs-tag"><<span class="hljs-title">property</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"hibernate.dialect"</span>></span>org.hibernate.dialect.MySQL5Dialect<span class="hljs-tag"></<span class="hljs-title">property</span>></span>
<span class="hljs-tag"><<span class="hljs-title">property</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"hibernate.show_sql"</span>></span>true<span class="hljs-tag"></<span class="hljs-title">property</span>></span>
<span class="hljs-comment"><!-- 加载所有映射 --></span>
<span class="hljs-tag"><<span class="hljs-title">mapping</span> <span class="hljs-attribute">resource</span>=<span class="hljs-value">"cn/itcast/a_hello/Employee.hbm.xml"</span>/></span>
<span class="hljs-tag"></<span class="hljs-title">session-factory</span>></span>
<span class="hljs-tag"></<span class="hljs-title">hibernate-configuration</span>></span>
</code>测试类 App.java
<code class=" hljs java">
<span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">App</span> {</span>
<span class="hljs-annotation">@Test</span>
<span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">testHello</span>() <span class="hljs-keyword">throws</span> Exception {
<span class="hljs-comment">// 对象</span>
Employee emp = <span class="hljs-keyword">new</span> Employee();
emp.setEmpName(<span class="hljs-string">"班长"</span>);
emp.setWorkDate(<span class="hljs-keyword">new</span> Date());
<span class="hljs-comment">// 获取加载配置文件的管理类对象</span>
Configuration config = <span class="hljs-keyword">new</span> Configuration();
config.configure(); <span class="hljs-comment">// 默认加载src/hibenrate.cfg.xml文件</span>
<span class="hljs-comment">// 创建session的工厂对象</span>
SessionFactory sf = config.buildSessionFactory();
<span class="hljs-comment">// 创建session (代表一个会话，与数据库连接的会话)</span>
Session session = sf.openSession();
<span class="hljs-comment">// 开启事务</span>
Transaction tx = session.beginTransaction();
<span class="hljs-comment">//保存-数据库</span>
session.save(emp);
<span class="hljs-comment">// 提交事务</span>
tx.commit();
<span class="hljs-comment">// 关闭</span>
session.close();
sf.close();
}
}
</code><code>|-- Configuration 配置管理类对象
config.configure(); 加载主配置文件的方法(hibernate.cfg.xml)
默认加载src/hibernate.cfg.xml
config.configure(“cn/config/hibernate.cfg.xml”);
加载指定路径下指定名称的主配置文件
config.buildSessionFactory(); 创建session的工厂对象
|-- SessionFactory session的工厂（或者说代表了这个hibernate.cfg.xml配置文件）
sf.openSession(); 创建一个sesison对象
sf.getCurrentSession(); 创建session或取出session对象
|--Session session对象维护了一个连接(Connection), 代表了与数据库连接的会话。
Hibernate最重要的对象： 只用使用hibernate与数据库操作，都用到这个对象
session.beginTransaction(); 开启一个事务； hibernate要求所有的与数据库的操作必须有事务的环境，否则报错！
更新：
session.save(obj); 保存一个对象
session.update(emp); 更新一个对象
session.saveOrUpdate(emp); 保存或者更新的方法：
没有设置主键，执行保存；
有设置主键，执行更新操作;
如果设置主键不存在报错！
主键查询：
session.get(Employee.class, 1); 主键查询
session.load(Employee.class, 1); 主键查询 (支持懒加载)
HQL查询：
HQL查询与SQL查询区别：
SQL: (结构化查询语句)查询的是表以及字段; 不区分大小写。
HQL: hibernate query language 即hibernate提供的面向对象的查询语言
查询的是对象以及对象的属性。
区分大小写。
Criteria查询：
完全面向对象的查询。
本地SQL查询：
复杂的查询，就要使用原生态的sql查询，也可以，就是本地sql查询的支持！
(缺点： 不能跨数据库平台！)
|-- Transaction hibernate事务对象
共性问题1：
ClassNotFoundException…., 缺少jar文件！
共性问题2：
如果程序执行程序，hibernate也有生成sql语句，但数据没有结果影响。
问题一般是事务忘记提交…….
遇到问题，一定看错误提示!
</code><code class=" hljs java">
<span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">EmployeeDaoImpl</span> <span class="hljs-keyword">implements</span> <span class="hljs-title">IEmployeeDao</span>{</span>
<span class="hljs-annotation">@Override</span>
<span class="hljs-keyword">public</span> Employee <span class="hljs-title">findById</span>(Serializable id) {
Session session = <span class="hljs-keyword">null</span>;
Transaction tx = <span class="hljs-keyword">null</span>;
<span class="hljs-keyword">try</span> {
<span class="hljs-comment">// 获取Session</span>
session = HibernateUtils.getSession();
<span class="hljs-comment">// 开启事务</span>
tx = session.beginTransaction();
<span class="hljs-comment">// 主键查询</span>
<span class="hljs-keyword">return</span> (Employee) session.get(Employee.class, id);
} <span class="hljs-keyword">catch</span> (Exception e) {
<span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> RuntimeException(e);
} <span class="hljs-keyword">finally</span> {
tx.commit();
session.close();
}
}
<span class="hljs-annotation">@Override</span>
<span class="hljs-keyword">public</span> List<Employee> <span class="hljs-title">getAll</span>() {
Session session = <span class="hljs-keyword">null</span>;
Transaction tx = <span class="hljs-keyword">null</span>;
<span class="hljs-keyword">try</span> {
session = HibernateUtils.getSession();
tx = session.beginTransaction();
<span class="hljs-comment">// HQL查询</span>
Query q = session.createQuery(<span class="hljs-string">"from Employee"</span>);
<span class="hljs-keyword">return</span> q.list();
} <span class="hljs-keyword">catch</span> (Exception e) {
<span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> RuntimeException(e);
} <span class="hljs-keyword">finally</span> {
tx.commit();
session.close();
}
}
<span class="hljs-annotation">@Override</span>
<span class="hljs-keyword">public</span> List<Employee> <span class="hljs-title">getAll</span>(String employeeName) {
Session session = <span class="hljs-keyword">null</span>;
Transaction tx = <span class="hljs-keyword">null</span>;
<span class="hljs-keyword">try</span> {
session = HibernateUtils.getSession();
tx = session.beginTransaction();
Query q =session.createQuery(<span class="hljs-string">"from Employee where empName=?"</span>);
<span class="hljs-comment">// 注意：参数索引从0开始</span>
q.setParameter(<span class="hljs-number">0</span>, employeeName);
<span class="hljs-comment">// 执行查询</span>
<span class="hljs-keyword">return</span> q.list();
} <span class="hljs-keyword">catch</span> (Exception e) {
<span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> RuntimeException(e);
} <span class="hljs-keyword">finally</span> {
tx.commit();
session.close();
}
}
<span class="hljs-annotation">@Override</span>
<span class="hljs-keyword">public</span> List<Employee> <span class="hljs-title">getAll</span>(<span class="hljs-keyword">int</span> index, <span class="hljs-keyword">int</span> count) {
Session session = <span class="hljs-keyword">null</span>;
Transaction tx = <span class="hljs-keyword">null</span>;
<span class="hljs-keyword">try</span> {
session = HibernateUtils.getSession();
tx = session.beginTransaction();
Query q = session.createQuery(<span class="hljs-string">"from Employee"</span>);
<span class="hljs-comment">// 设置分页参数</span>
q.setFirstResult(index); <span class="hljs-comment">// 查询的其实行 </span>
q.setMaxResults(count); <span class="hljs-comment">// 查询返回的行数</span>
List<Employee> list = q.list();
<span class="hljs-keyword">return</span> list;
} <span class="hljs-keyword">catch</span> (Exception e) {
<span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> RuntimeException(e);
} <span class="hljs-keyword">finally</span> {
tx.commit();
session.close();
}
}
<span class="hljs-annotation">@Override</span>
<span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">save</span>(Employee emp) {
Session session = <span class="hljs-keyword">null</span>;
Transaction tx = <span class="hljs-keyword">null</span>;
<span class="hljs-keyword">try</span> {
session = HibernateUtils.getSession();
tx = session.beginTransaction();
<span class="hljs-comment">// 执行保存操作</span>
session.save(emp);
} <span class="hljs-keyword">catch</span> (Exception e) {
<span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> RuntimeException(e);
} <span class="hljs-keyword">finally</span> {
tx.commit();
session.close();
}
}
<span class="hljs-annotation">@Override</span>
<span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">update</span>(Employee emp) {
Session session = <span class="hljs-keyword">null</span>;
Transaction tx = <span class="hljs-keyword">null</span>;
<span class="hljs-keyword">try</span> {
session = HibernateUtils.getSession();
tx = session.beginTransaction();
session.update(emp);
} <span class="hljs-keyword">catch</span> (Exception e) {
<span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> RuntimeException(e);
} <span class="hljs-keyword">finally</span> {
tx.commit();
session.close();
}
}
<span class="hljs-annotation">@Override</span>
<span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">delete</span>(Serializable id) {
Session session = <span class="hljs-keyword">null</span>;
Transaction tx = <span class="hljs-keyword">null</span>;
<span class="hljs-keyword">try</span> {
session = HibernateUtils.getSession();
tx = session.beginTransaction();
<span class="hljs-comment">// 先根据id查询对象，再判断删除</span>
Object obj = session.get(Employee.class, id);
<span class="hljs-keyword">if</span> (obj != <span class="hljs-keyword">null</span>) {
session.delete(obj);
}
} <span class="hljs-keyword">catch</span> (Exception e) {
<span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> RuntimeException(e);
} <span class="hljs-keyword">finally</span> {
tx.commit();
session.close();
}
}
}</code><code>Hibernate.cfg.xml
主配置文件中主要配置：数据库连接信息、其他参数、映射信息！
常用配置查看源码：
hibernate-distribution-3.6.0.Final\project\etc\hibernate.properties
</code><code>例如： ## MySQL #hibernate.dialect org.hibernate.dialect.MySQLDialect #hibernate.dialect org.hibernate.dialect.MySQLInnoDBDialect #hibernate.dialect org.hibernate.dialect.MySQLMyISAMDialect #hibernate.connection.driver_class com.mysql.jdbc.Driver #hibernate.connection.url jdbc:mysql:///test #hibernate.connection.username gavin #hibernate.connection.password </code>
Hibernate.properties
<code>#hibernate.hbm2ddl.auto create-drop 每次在创建sessionFactory时候执行创建表；
当调用sesisonFactory的close方法的时候，删除表！
#hibernate.hbm2ddl.auto create 每次都重新建表； 如果表已经存在就先删除再创建
#hibernate.hbm2ddl.auto update 如果表不存在就创建； 表存在就不创建；
#hibernate.hbm2ddl.auto validate (生成环境时候) 执行验证： 当映射文件的内容与数据库表结构不一样的时候就报错！
</code>代码自动建表
<code class=" hljs java">
<span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">App_ddl</span> {</span>
<span class="hljs-comment">// 自动建表</span>
<span class="hljs-annotation">@Test</span>
<span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">testCreate</span>() <span class="hljs-keyword">throws</span> Exception {
<span class="hljs-comment">// 创建配置管理类对象</span>
Configuration config = <span class="hljs-keyword">new</span> Configuration();
<span class="hljs-comment">// 加载主配置文件</span>
config.configure();
<span class="hljs-comment">// 创建工具类对象</span>
SchemaExport export = <span class="hljs-keyword">new</span> SchemaExport(config);
<span class="hljs-comment">// 建表</span>
<span class="hljs-comment">// 第一个参数： 是否在控制台打印建表语句</span>
<span class="hljs-comment">// 第二个参数： 是否执行脚本</span>
export.create(<span class="hljs-keyword">true</span>, <span class="hljs-keyword">true</span>);
}
}
</code><code>1. 普通字段类型
2. 主键映射
单列主键映射
多列作为主键映射
主键生成策略，查看api： 5.1.2.2.1. Various additional generators
数据库：
一个表能否有多个主键？ 不能。
为什么要设置主键？ 数据库存储的数据都是有效的，必须保持唯一。
(为什么把id作为主键？)
因为表中通常找不到合适的列作为唯一列即主键，所以为了方法用id列，因为id是数据库系统维护可以保证唯一，所以就把这列作为主键!
联合/复合主键
如果找不到合适的列作为主键，出来用id列以外，我们一般用联合主键，即多列的值作为一个主键，从而确保记录的唯一性。
</code><code class=" hljs xml"><span class="hljs-pi"><?xml version="1.0"?></span>
<span class="hljs-doctype"><!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"></span>
<span class="hljs-comment"><!-- 映射文件: 映射一个实体类对象； 描述一个对象最终实现可以直接保存对象数据到数据库中。 --></span>
<span class="hljs-comment"><!--
package: 要映射的对象所在的包(可选,如果不指定,此文件所有的类都要指定全路径)
auto-import 默认为true， 在写hql的时候自动导入包名
如果指定为false, 再写hql的时候必须要写上类的全名；
如：session.createQuery("from cn.itcast.c_hbm_config.Employee").list();
--></span>
<span class="hljs-tag"><<span class="hljs-title">hibernate-mapping</span> <span class="hljs-attribute">package</span>=<span class="hljs-value">"cn.itcast.c_hbm_config"</span> <span class="hljs-attribute">auto-import</span>=<span class="hljs-value">"true"</span>></span>
<span class="hljs-comment"><!--
class 映射某一个对象的(一般情况，一个对象写一个映射文件，即一个class节点)
name 指定要映射的对象的类型
table 指定对象对应的表；
如果没有指定表名，默认与对象名称一样
--></span>
<span class="hljs-tag"><<span class="hljs-title">class</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"Employee"</span> <span class="hljs-attribute">table</span>=<span class="hljs-value">"employee"</span>></span>
<span class="hljs-comment"><!-- 主键 ，映射--></span>
<span class="hljs-tag"><<span class="hljs-title">id</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"empId"</span> <span class="hljs-attribute">column</span>=<span class="hljs-value">"id"</span>></span>
<span class="hljs-comment"><!--
主键的生成策略
identity 自增长(mysql,db2)
sequence 自增长(序列)， oracle中自增长是以序列方法实现
native 自增长【会根据底层数据库自增长的方式选择identity或sequence】
如果是mysql数据库, 采用的自增长方式是identity
如果是oracle数据库， 使用sequence序列的方式实现自增长
increment 自增长(会有并发访问的问题，一般在服务器集群环境使用会存在问题。)
assigned 指定主键生成策略为手动指定主键的值
uuid 指定uuid随机生成的唯一的值
foreign (外键的方式， one-to-one讲)
--></span>
<span class="hljs-tag"><<span class="hljs-title">generator</span> <span class="hljs-attribute">class</span>=<span class="hljs-value">"uuid"</span>/></span>
<span class="hljs-tag"></<span class="hljs-title">id</span>></span>
<span class="hljs-comment"><!--
普通字段映射
property
name 指定对象的属性名称
column 指定对象属性对应的表的字段名称，如果不写默认与对象属性一致。
length 指定字符的长度, 默认为255
type 指定映射表的字段的类型，如果不指定会匹配属性的类型
java类型： 必须写全名
hibernate类型： 直接写类型，都是小写
--></span>
<span class="hljs-tag"><<span class="hljs-title">property</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"empName"</span> <span class="hljs-attribute">column</span>=<span class="hljs-value">"empName"</span> <span class="hljs-attribute">type</span>=<span class="hljs-value">"java.lang.String"</span> <span class="hljs-attribute">length</span>=<span class="hljs-value">"20"</span>></span><span class="hljs-tag"></<span class="hljs-title">property</span>></span>
<span class="hljs-tag"><<span class="hljs-title">property</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"workDate"</span> <span class="hljs-attribute">type</span>=<span class="hljs-value">"java.util.Date"</span>></span><span class="hljs-tag"></<span class="hljs-title">property</span>></span>
<span class="hljs-comment"><!-- 如果列名称为数据库关键字，需要用反引号或改列名。 --></span>
<span class="hljs-tag"><<span class="hljs-title">property</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"desc"</span> <span class="hljs-attribute">column</span>=<span class="hljs-value">"`desc`"</span> <span class="hljs-attribute">type</span>=<span class="hljs-value">"java.lang.String"</span>></span><span class="hljs-tag"></<span class="hljs-title">property</span>></span>
<span class="hljs-tag"></<span class="hljs-title">class</span>></span>
<span class="hljs-tag"></<span class="hljs-title">hibernate-mapping</span>></span>
</code>对象与主键
<code class=" hljs java"><span class="hljs-comment">// 复合主键类</span>
<span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">CompositeKeys</span> <span class="hljs-keyword">implements</span> <span class="hljs-title">Serializable</span>{</span>
<span class="hljs-keyword">private</span> String userName;
<span class="hljs-keyword">private</span> String address;
<span class="hljs-comment">// .. get/set</span>
}</code><code class=" hljs cs"><span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> User {
<span class="hljs-comment">// 名字跟地址，不会重复</span>
<span class="hljs-keyword">private</span> CompositeKeys keys;
<span class="hljs-keyword">private</span> <span class="hljs-keyword">int</span> age;
}</code>User.hbm.xml
<code class=" hljs xml"><span class="hljs-pi"><?xml version="1.0"?></span>
<span class="hljs-doctype"><!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"></span>
<span class="hljs-tag"><<span class="hljs-title">hibernate-mapping</span> <span class="hljs-attribute">package</span>=<span class="hljs-value">"cn.itcast.d_compositeKey"</span> <span class="hljs-attribute">auto-import</span>=<span class="hljs-value">"true"</span>></span>
<span class="hljs-tag"><<span class="hljs-title">class</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"User"</span>></span>
<span class="hljs-comment"><!-- 复合主键映射 --></span>
<span class="hljs-tag"><<span class="hljs-title">composite-id</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"keys"</span>></span>
<span class="hljs-tag"><<span class="hljs-title">key-property</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"userName"</span> <span class="hljs-attribute">type</span>=<span class="hljs-value">"string"</span>></span><span class="hljs-tag"></<span class="hljs-title">key-property</span>></span>
<span class="hljs-tag"><<span class="hljs-title">key-property</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"address"</span> <span class="hljs-attribute">type</span>=<span class="hljs-value">"string"</span>></span><span class="hljs-tag"></<span class="hljs-title">key-property</span>></span>
<span class="hljs-tag"></<span class="hljs-title">composite-id</span>></span>
<span class="hljs-tag"><<span class="hljs-title">property</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"age"</span> <span class="hljs-attribute">type</span>=<span class="hljs-value">"int"</span>></span><span class="hljs-tag"></<span class="hljs-title">property</span>></span>
<span class="hljs-tag"></<span class="hljs-title">class</span>></span>
<span class="hljs-tag"></<span class="hljs-title">hibernate-mapping</span>></span></code>APP.java
<code class=" hljs cs"><span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> App2 {
<span class="hljs-keyword">private</span> <span class="hljs-keyword">static</span> SessionFactory sf;
<span class="hljs-keyword">static</span> {
<span class="hljs-comment">// 创建sf对象</span>
sf = <span class="hljs-keyword">new</span> Configuration()
.configure()
.addClass(User.class) <span class="hljs-comment">//（测试） 会自动加载映射文件：Employee.hbm.xml</span>
.buildSessionFactory();
}
<span class="hljs-comment">//1. 保存对象</span>
@Test
<span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">testSave</span>() throws Exception {
Session session = sf.openSession();
Transaction tx = session.beginTransaction();
<span class="hljs-comment">// 对象</span>
CompositeKeys keys = <span class="hljs-keyword">new</span> CompositeKeys();
keys.setAddress(<span class="hljs-string">"广州棠东"</span>);
keys.setUserName(<span class="hljs-string">"Jack"</span>);
User user = <span class="hljs-keyword">new</span> User();
user.setAge(<span class="hljs-number">20</span>);
user.setKeys(keys);
<span class="hljs-comment">// 保存</span>
session.save(user);
tx.commit();
session.close();
}
@Test
<span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">testGet</span>() throws Exception {
Session session = sf.openSession();
Transaction tx = session.beginTransaction();
<span class="hljs-comment">//构建主键再查询</span>
CompositeKeys keys = <span class="hljs-keyword">new</span> CompositeKeys();
keys.setAddress(<span class="hljs-string">"广州棠东"</span>);
keys.setUserName(<span class="hljs-string">"Jack"</span>);
<span class="hljs-comment">// 主键查询</span>
User user = (User) session.<span class="hljs-keyword">get</span>(User.class, keys);
<span class="hljs-comment">// 测试输出</span>
<span class="hljs-keyword">if</span> (user != <span class="hljs-keyword">null</span>){
System.<span class="hljs-keyword">out</span>.println(user.getKeys().getUserName());
System.<span class="hljs-keyword">out</span>.println(user.getKeys().getAddress());
System.<span class="hljs-keyword">out</span>.println(user.getAge());
}
tx.commit();
session.close();
}
}
</code>
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