Hibernate注解开发示例

-------------------------------------------------------------------customer-----------------------------------------------------------------------------------------------------------------------------

@Entity   /实体
@Table(name="t_customer")     //数据库表的名称,
public class Customer {
@Id      -------------主键
@GeneratedValue(strategy=GenerationType.IDENTITY)    //主键生成策略,自动增长
//@GenericGenerator(name="myuuid",strategy="uuid")    //代理主键为UUID时的操作
//@GeneratedValue(generator="myuuid")
private Integer id ;
private String name ;
@OneToMany(targetEntity=Order.class,mappedBy="c")  //目标实体, mappBy="c"代表外键的维护由对方也就是Order来维护.相当于inverse=true,这时如果保存客户时,级联保存订单.是可以的,但是不能维护外键,必须在代码中添加订单和客户的关系.
@Cascade(CascadeType.SAVE_UPDATE )     //
private Set<Order> orders = new HashSet<Order>() ;

-------------------------------------------------------------------Order----------------------------------------------------------------------------------------------------------------------------

@Entity  //实体
@Table(name="t_Order")  //数据库表的名称,数据库名在核心配置文件有,在这不用写.
public class Order {
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private Integer id ;  //用引用类型,便于转换字符串,为空时返回值为null.
private Double money;
private String receiverInfo;
@ManyToOne(targetEntity=Customer.class)  //目标实体
@JoinColumn(name = "customer_id")     //指定外键列
private Customer c ;    //描述订单属于某一个客户

-------------------------------------------------------------------Test----------------------------------------------------------------------------------------------------------------------------

@Test
public void test01(){
//调用工具类,创建session.
Session session = HibernateUtils.openSession();
//开启事务
session.beginTransaction();
//创建
Customer c = new Customer();c.setName("wangwu");
Order o1 = new Order();o1.setMoney(1000.0); o1.setReceiverInfo("beijing");
Order o2 = new Order();o2.setMoney(1000.0);o2.setReceiverInfo("beijing");
//订单关联客户,保存订单时保存客户
//------------------------------------为了维护外键(要想显示外键必须写上)
o1.setC(c);o2.setC(c);
//session.save(o1);
//session.save(o2);
//客户关联订单,既保存客户时保存订单,为了进行级联操作
c.getOrders().add(o2); c.getOrders().add(o1);session.save(c);
//事务提交和session关闭
session.getTransaction().commit();
session.close();

-------------------------------------------------------------------hibernate.cfg.xml  ----------------------------------------------------------------------------------------------------------------------------

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"> -----------configuration约束

<hibernate-configuration>

<session-factory>
<!-- 配置关于数据库连接的四个项 driverClass url username password -->
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql:///hibernatetest</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">123</property>

<!-- 设置连接提供者 -->
<property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
<!-- c3p0连接池的配置 -->
<property name="hibernate.c3p0.max_size">20</property> <!-- 最大连接池 -->
<property name="hibernate.c3p0.min_size">5</property> <!-- 最小连接数 -->
<property name="hibernate.c3p0.timeout">120</property> <!-- 超时 -->
<property name="hibernate.c3p0.idle_test_period">3000</property> <!-- 空闲连接 -->

<!-- 可以将向数据库发送的sql显示出来 -->
<property name="hibernate.show_sql">true</property>
<!-- 格式化sql -->
<property name="hibernate.format_sql">true</property>

<!-- hibernate的方言 -->
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>

<!-- 自动创建表 -->
<property name="hibernate.hbm2ddl.auto">update</property>

<!-- 用于设置事务提交方式 -->
<property name="hibernate.connection.autocommit">false</property>

<!-- 配置hibernate的映射文件所在位置  如果用xml开发的话,Class换成resource-->
<mapping class="cn.itcast.domain.Customer" />
<mapping class="cn.itcast.domain.Order" />

</session-factory>

</hibernate-configuration>

-------------------------------------------------------------------删除操作 ----------------------------------------------------------------------------------------------------------------------------

@Test
public void test02(){
Session session = HibernateUtils.openSession();
session.beginTransaction();
//得到客户
Customer c = session.get(Customer.class, 2);
//得到订单
Order o = session.get(Order.class, 3);
//删除客户的订单
c.getOrders().remove(o);-------------------------------------在客户实体类的@OneTOMany括号里添加orphanRemoval=true
//session.delete(c);--------------------------------------------如果直接删除某个客户,在@OneTOMany下面使用hibernate提供的注解@cascade(CascadeType.delete)
//提交事务
session.getTransaction().commit();
session.close();
}