Hibernate之一对多（多对一）

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一、双向关联级联保存客户订单

1、搭建环境，项目结构如下

2、代码及配置如下(数据库里订单表不能用order，因为order是数据库关键字)（客户外键cid和订单表外键cid要在配置中写一致）

package com.hjp.onetomany;

import java.util.HashSet;

import java.util.Set;

/**

 * Created by JiaPeng on 2016/1/2.

 */

public class Customer {

    private int id;

    private String name;

    private Set<Order> orderSet=new HashSet<Order>() ;

    public Set<Order> getOrderSet() {

        return orderSet;

    }

    public void setOrderSet(Set<Order> orderSet) {

        this.orderSet = orderSet;

    }

    public int getId() {

        return id;

    }

    public void setId(int id) {

        this.id = id;

    }

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    @Override

    public String toString() {

        return "Customer{" +

                "id=" + id +

                ", name='" + name + '\'' +

                ", orderSet=" + orderSet +

                '}';

    }

}

Customer

<?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>

  <class name="com.hjp.onetomany.Customer" table="customer">

      <id name="id">

          <generator class="native"></generator>

      </id>

      <property name="name"></property>

      <set name="orderSet">

          <key column="cid"></key>

          <one-to-many class="com.hjp.onetomany.Order"></one-to-many>

      </set>

  </class>

</hibernate-mapping>

customer.hbm.xml

package com.hjp.onetomany;

/**

 * Created by JiaPeng on 2016/1/2.

 */

public class Order {

    private int id;

    private double price;

    private Customer customer=new Customer();

    public int getId() {

        return id;

    }

    public void setId(int id) {

        this.id = id;

    }

    public double getPrice() {

        return price;

    }

    public void setPrice(double price) {

        this.price = price;

    }

    public Customer getCustomer() {

        return customer;

    }

    public void setCustomer(Customer customer) {

        this.customer = customer;

    }

    @Override

    public String toString() {

        return "Order{" +

                "price=" + price +

                ", id=" + id +

                '}';

    }

}

Order

<?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>

   <class name="com.hjp.onetomany.Order" table="orders">

       <id name="id">

           <generator class="native"></generator>

       </id>

       <property name="price"></property>

       <many-to-one name="customer" class="com.hjp.onetomany.Customer" column="cid"></many-to-one>

   </class>

</hibernate-mapping>

order.hbm.xml

package com.hjp.utils;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.Configuration;

/**

 * Created by JiaPeng on 2016/1/2.

 */

public class HibernateUtils {

private static final SessionFactory sessionFactory;

    static {

        Configuration configuration=new Configuration().configure();

        sessionFactory=configuration.buildSessionFactory();

    }

    public static Session getSession(){

        return sessionFactory.openSession();

    }

}

HibernateUtils

<?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>

    <session-factory>

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

        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>

        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/h1</property>

        <property name="hibernate.connection.username">root</property>

        <property name="hibernate.connection.password">hjp123</property>

        <!--设置c3p0-->

        <property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>

        <!--c3p0连接池配置信息-->

        <property name="c3p0.min_size">5</property>

        <property name="c3p0.max_size">20</property>

        <property name="c3p0.timeout">120</property>

        <property name="c3p0.idle_test_period">3000</property>

        <!--显示SQL并格式化-->

        <property name="hibernate.show_sql">true</property>

        <property name="hibernate.format_sql">true</property>

        <!--ddl生成策略，后面可以改为update-->

        <property name="hibernate.hbm2ddl.auto">create</property>

        <!--导入映射文件-->

        <!--<mapping resource="com/hjp/hbm/customer.hbm.xml"></mapping>-->

        <mapping resource="com/hjp/onetomany/customer.hbm.xml"></mapping>

        <mapping resource="com/hjp/onetomany/order.hbm.xml"></mapping>

    </session-factory>

</hibernate-configuration>

hibernate.cfg.xml

  @Test

    public void func2() {

        Session session = HibernateUtils.getSession();

        session.beginTransaction();

        //创建客户

        Customer customer = new Customer();

        customer.setName("张三");

        //创建两个订单

        Order order1 = new Order();

        order1.setPrice(121);

        Order order2 = new Order();

        order2.setPrice(122);

        //客户关联订单

        customer.getOrderSet().add(order1);

        customer.getOrderSet().add(order2);

        //订单关联客户

        order1.setCustomer(customer);

        order2.setCustomer(customer);

        session.save(customer);

        session.save(order1);

        session.save(order2);

        session.getTransaction().commit();

        session.close();

    }