Hibernate JPA注解一对多

下面演示JPA注解方式的一对多关系映射。以客户 和 订单 为例。

更多一对多的需求可以参考XML版本的一对多映射：

http://www.yiidian.com/hibernate/hibernate-one2many.html

一、实体类

Customer:

/**
 * 客户（一方）
 * @author http://www.yiidian.com
 * 
 */
@Entity
@Table(name="t_customer")
public class Customer {
	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	@Column(name="id")
	private Integer id;
	@Column(name="name")
	private String name;
	@Column(name="gender")
	private String gender;
	
	@Transient // 临时字段，不反映到数据库中
	private Boolean isMarried;
	public Boolean getIsMarried() {
		return isMarried;
	}
	
	//关联订单
	@OneToMany(targetEntity=Order.class,mappedBy="customer")
	private Set<Order> orders = new HashSet<Order>();
	
	
	public Set<Order> getOrders() {
		return orders;
	}
	public void setOrders(Set<Order> orders) {
		this.orders = orders;
	}
	public void setIsMarried(Boolean isMarried) {
		this.isMarried = isMarried;
	}
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getGender() {
		return gender;
	}
	public void setGender(String gender) {
		this.gender = gender;
	}

}

Order:

/**
 * 订单（多方）
 * @author http://www.yiidian.com
 *
 */
@Entity
@Table(name="t_order")
public class Order implements Serializable{

	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	@Column(name="id")
	private Integer id;
	
	@Column(name="orderno")
	private String orderno;
	
	//关联客户
	@ManyToOne(targetEntity=Customer.class)
	@JoinColumn(name="cust_id")
	private Customer customer;

	public Integer getId() {
		return id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getOrderno() {
		return orderno;
	}

	public void setOrderno(String orderno) {
		this.orderno = orderno;
	}

	public Customer getCustomer() {
		return customer;
	}

	public void setCustomer(Customer customer) {
		this.customer = customer;
	}
}

二、配置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">
	
<hibernate-configuration>	
	<!-- 连接数据库的参数 -->
<session-factory>
	<!-- 1.连接数据库参数 -->
	<property name="hibernate.connection.driver_class">
		com.mysql.jdbc.Driver
	</property>
	<property name="hibernate.connection.url">
		jdbc:mysql://localhost:3306/hibernate
	</property>
	<property name="hibernate.connection.username">root</property>
	<property name="hibernate.connection.password">root</property>

	<!-- 整合c3p0 -->
	<property name="hibernate.connection.provider_class">
		org.hibernate.c3p0.internal.C3P0ConnectionProvider
	</property>
	<!-- c3p0详细配置 -->
	<property name="c3p0.min_size">10</property>
	<property name="c3p0.max_size">20</property>

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

	<!-- 2.hibernate扩展参数 -->
	<property name="hibernate.show_sql">true</property>
	<property name="hibernate.format_sql">true</property>
	<property name="hibernate.hbm2ddl.auto">update</property>

	<!-- 让session被TheadLocal管理 -->
	<property name="hibernate.current_session_context_class">
		thread
	</property>
	<property name="dialect"></property>

	<mapping class="com.yiidian.domain.Customer" />
	<mapping class="com.yiidian.domain.Order" />

</session-factory>
</hibernate-configuration>	

三、编写测试类

/**
 * 演示一对多的映射
 * @author lenovo
 *
 */
public class Demo {

	
	@Test
	public void test1(){
		Session session = HibernateUtil.getSession();
		Transaction tx = session.beginTransaction();
		
		Customer cust = new Customer();
		cust.setName("王五");
		session.save(cust);
	
		Order o1 = new Order();
		o1.setOrderno("201709001");
		
		Order o2 = new Order();
		o2.setOrderno("201709002");
		
		cust.getOrders().add(o1);
		cust.getOrders().add(o2);
		o1.setCustomer(cust);
		o2.setCustomer(cust);
		
		session.save(cust);
		session.save(o1);
		session.save(o2);
		
		tx.commit();
	}
	
}

执行程序，控制台输出：

Hibernate: 
    insert 
    into
        t_customer
        (gender, name) 
    values
        (?, ?)
Hibernate: 
    insert 
    into
        t_order
        (cust_id, orderno) 
    values
        (?, ?)
Hibernate: 
    insert 
    into
        t_order
        (cust_id, orderno) 
    values
        (?, ?)