Hibernate入门(七)一对多入门案例

一对多

场景模拟:用户(一)对订单(多)

1.建表

　　创建客户表，字段有：客户id，客户姓名，客户性别，客户年龄，客户年纪，客户电话。

　　创建订单表，字段有：订单编号，明细编号，客户编号(外键)

DROP TABLE IF EXISTS ordersA;
DROP TABLE IF EXISTS customerA;
 
CREATE TABLE customerA(
    cust_id        TINYINT  PRIMARY KEY AUTO_INCREMENT,
    cust_name　　 　VARCHAR(30),
    cust_gender 　　CHAR(5),
    cust_age       SMALLINT,
    cust_phone     VARCHAR(20)
);

CREATE TABLE ordersA(
    order_id VARCHAR(50) PRIMARY KEY,
    detail_id   VARCHAR(50),
    cust_order_id TINYINT,
    CONSTRAINT fk_customerA_ordersA FOREIGN KEY(cust_order_id) REFERENCES customerA(cust_id) ON DELETE CASCADE
);

2.创建项目，配置hibernate.cfg.xml主配置文件

<?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.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.url">jdbc:mysql:///test</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.connection.password">123456</property>

        <property name="hibernate.show_sql">true</property>
        <property name="hibernate.format_sql">true</property>
        <property name="hibernate.hbm2ddl.auto">update</property>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>

        <!-- 指定session与当前线程绑定 -->
        <property name="hibernate.current_session_context_class">thread</property>

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

3.创建实体

　　创建用户实体类:基本属性+配置一对多的属性(set集合存储多个订单)

　   创建订单实体类:基本属性+配置多对一的属性(Customer类存储客户实体)

package deep.domain;

import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;

/**
 * 客户实体类
 * @author DeepSleeping
 *
 */
public class Customer implements Serializable {

    private static final long serialVersionUID = 1L;
    private Integer cust_id;
    private String cust_name;
    private String cust_gender;
    private Integer cust_age;
    private String cust_phone;

    /*
     * 一对多
     * */
    private Set<Order> ods = new HashSet<Order>();

    public Integer getCust_id() {
        return cust_id;
    }

    public void setCust_id(Integer cust_id) {
        this.cust_id = cust_id;
    }

    public String getCust_name() {
        return cust_name;
    }

    public void setCust_name(String cust_name) {
        this.cust_name = cust_name;
    }

    public String getCust_gender() {
        return cust_gender;
    }

    public void setCust_gender(String cust_gender) {
        this.cust_gender = cust_gender;
    }

    public Integer getCust_age() {
        return cust_age;
    }

    public void setCust_age(Integer cust_age) {
        this.cust_age = cust_age;
    }

    public String getCust_phone() {
        return cust_phone;
    }

    public void setCust_phone(String cust_phone) {
        this.cust_phone = cust_phone;
    }

    public Set<Order> getOds() {
        return ods;
    }

    public void setOds(Set<Order> ods) {
        this.ods = ods;
    }

}

package deep.domain;

import java.io.Serializable;

/**
 * 订单实体类
 * @author DeepSleeping
 *
 */
public class Order implements Serializable{

    private static final long serialVersionUID = 1L;
    private String order_id;
    private String detail_id;

    /*
     * 多对一
     */
    private Customer cst;

    public String getOrder_id() {
        return order_id;
    }
    public void setOrder_id(String order_id) {
        this.order_id = order_id;
    }
    public String getDetail_id() {
        return detail_id;
    }
    public void setDetail_id(String detail_id) {
        this.detail_id = detail_id;
    }
    public Customer getCst() {
        return cst;
    }
    public void setCst(Customer cst) {
        this.cst = cst;
    }

}

4.配置实体的映射文件:Customer.hbm.xml,Order.hbm.xml

　　Customer.hbm.xml中的set标签对中：

　　set：存储多的一方的集合 name:存储多的一方的集合属性名

　　key标签对:配置外键

　　column:是数据库中外键的字段名(注意这里写的名一定要与后面多方中配置外键的名称一致，否则就会创建多个外键)

<one-to-many> 是表示，我这里是一对多，对的多的一方的实体类的路径是:class = "order"(这里只写order是因为在配置文件中我已经用package定位到实体类的包下了)

<?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 package="deep.domain">
    <class name="Customer" table="customera">
        <id name="cust_id" column = "cust_id">
            <generator class="native"></generator>
        </id>

        <property name="cust_name" column = "cust_name"></property>
        <property name="cust_gender" column = "cust_gender"></property>
        <property name="cust_age" column = "cust_age"></property>
        <property name="cust_phone" column = "cust_phone"></property>

        <!-- 配置一对多属性 -->
        <set name="ods">
            <key column="cust_order_id"></key>
            <one-to-many class="Order"/>
        </set>

    </class>

</hibernate-mapping>

<?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 package="deep.domain">
    <class name="Order" table="ordersa">
        <id name="order_id" column = "order_id">
            <generator class="uuid"></generator>
        </id>

        <property name="detail_id" column = "detail_id"></property>

        <!-- 配置多对一属性 -->
        <many-to-one name="cst" column="cust_order_id" class="Customer"/>
    </class>
</hibernate-mapping>

5.在主配置文件中引入两个实体对应的映射文件

<mapping resource="deep/domain/Customer.hbm.xml"/>
<mapping resource="deep/domain/Order.hbm.xml"/>

6.添加订单到客户id为1的客户中

package deep.test;

import java.util.UUID;

import org.hibernate.Session;
import org.junit.Test;

import deep.common.HibernateUtils;
import deep.domain.Customer;
import deep.domain.Order;

public class TestClass {

    /**
     * 添加订单到客户
     */
    @Test
    public void fun(){

        Session session = HibernateUtils.getSession();
        session.getTransaction().begin();

        try {
            //获取客户 持久
            Customer cst = session.get(Customer.class, 1);
            //新建订单 瞬时
            Order od = new Order();
            od.setOrder_id(UUID.randomUUID().toString());
            od.setDetail_id(UUID.randomUUID().toString());
            //表达客户和订单的关系
            cst.getOds().add(od);
            //表达订单和客户的关系
            od.setCst(cst);
            //持久化订单
            session.save(od);
        } catch (Exception e) {
            session.getTransaction().rollback();
            e.printStackTrace();
        }

        session.getTransaction().commit();
    }
}

添加订单成功！