本文详细介绍了一对多关系在Hibernate框架中的实现，包括SQL建表语句、Java实体类定义、XML映射文件配置及测试代码，展示了如何通过ORM将Java对象与数据库表进行映射。
SQL
use hibernate_day03;
CREATE TABLE `cst_customer` (
`cust_id` bigint(32) NOT NULL AUTO_INCREMENT COMMENT '客户编号(主键)',
`cust_name` varchar(32) DEFAULT NULL COMMENT '客户名称(公司名称)',
`cust_source` varchar(32) DEFAULT NULL COMMENT '客户信息来源',
`cust_industry` varchar(32) DEFAULT NULL COMMENT '客户所属行业',
`cust_level` varchar(32) DEFAULT NULL COMMENT '客户级别',
`cust_phone` varchar(64) DEFAULT NULL COMMENT '固定电话',
`cust_mobile` varchar(16) DEFAULT NULL COMMENT '移动电话',
PRIMARY KEY (`cust_id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
CREATE TABLE `cst_linkman` (
`lkm_id` bigint(32) NOT NULL AUTO_INCREMENT COMMENT '联系人编号(主键)',
`lkm_name` varchar(16) DEFAULT NULL COMMENT '联系人姓名',
`lkm_cust_id` bigint(32) NOT NULL COMMENT '客户id',
`lkm_gender` char(1) DEFAULT NULL COMMENT '联系人性别',
`lkm_phone` varchar(16) DEFAULT NULL COMMENT '联系人办公电话',
`lkm_mobile` varchar(16) DEFAULT NULL COMMENT '联系人手机',
`lkm_email` varchar(64) DEFAULT NULL COMMENT '联系人邮箱',
`lkm_qq` varchar(16) DEFAULT NULL COMMENT '联系人qq',
`lkm_position` varchar(16) DEFAULT NULL COMMENT '联系人职位',
`lkm_memo` varchar(512) DEFAULT NULL COMMENT '联系人备注',
PRIMARY KEY (`lkm_id`),
KEY `FK_cst_linkman_lkm_cust_id` (`lkm_cust_id`),
CONSTRAINT `FK_cst_linkman_lkm_cust_id` FOREIGN KEY (`lkm_cust_id`) REFERENCES `cst_customer` (`cust_id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;
Customer.java
import java.util.HashSet;
import java.util.Set;
/**
* 客户的实体
* @author zhang
*
*/
public class Customer {
private Long cust_id;
private String cust_name;
private String cust_source;
private String cust_industry;
private String cust_level;
private String cust_phone;
private String cust_mobile;
//通过 ORM方式表示：一个客户对应的多个联系人
//防止的多的一方的集合。Hibernate默认使用的是Set集合
private Set<LinkMan> linkMans=new HashSet<LinkMan>();
//-----省略了get和set方法
}
LinkMan.java
public class LinkMan {
private Long lkm_id;
private String lkm_name;
private String lkm_gender;
private String lkm_phone;
private String lkm_mobile;
private String lkm_email;
private String lkm_qq;
private String lkm_position;
private String lkm_memo;
//通过ORM方式表示：一个联系人只能属于一个客户
//放置的是一的一方的对象
private Customer customer;
//-----省略get和set方法
}
Customer.hbm.xml
<?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.hibernate.domain.Customer" table="cst_customer">
<!-- 建立OID与主键映射 -->
<id name="cust_id" column="cust_id">
<generator class="native"/>
</id>
<!-- 建立普通属性和表的字段的对应 -->
<property name="cust_name" column="cust_name"/>
<property name="cust_source" column="cust_source"/>
<property name="cust_industry" column="cust_industry"/>
<property name="cust_level" column="cust_level"/>
<property name="cust_phone" column="cust_phone"/>
<property name="cust_mobile" column="cust_mobile"/>
<!-- 配置一对多的映射：放置的多的一方的集合 -->
<!--
set标签
* name ：多的一方的对象集合的属性名称
-->
<set name="linkMans">
<!--
key标签
* column:多的一方的外键的名称
-->
<key column="lkm_cust_id"/>
<!--
one-to-many标签
* class :多的一方的全路径
-->
<one-to-many class="com.hibernate.domain.LinkMan"/>
</set>
</class>
</hibernate-mapping>
LinkMan.hbm.xml
<?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.hibernate.domain.LinkMan" table="cst_linkman">
<!-- 建立OID与主键映射 -->
<id name="lkm_id" column="lkm_id">
<generator class="native"/>
</id>
<!-- 建立普通属性与表字段映射 -->
<property name="lkm_name"/>
<property name="lkm_gender"/>
<property name="lkm_phone"/>
<property name="lkm_mobile"/>
<property name="lkm_email"/>
<property name="lkm_qq"/>
<property name="lkm_position"/>
<property name="lkm_memo"/>
<!-- 配置多对一的关系：放置的是一的一方的对象 -->
<!--
many-to-one标签
* name :一的一方的对象的属性名称
* class :一的一方的全路径
* column ：在多的一方的表的外键的名称
-->
<many-to-one name="customer" class="com.hibernate.domain.Customer" column="lkm_cust_id"/>
</class>
</hibernate-mapping>
src下的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>
<session-factory>
<!-- 连接数据库的基本参数 -->
<!-- hibernate-release-5.0.7.Final\project\etc\hibernate.properties -->
<!-- localhost:3306 -->
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql:///hibernate_day03</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">password</property>
<!-- 配置Hibernate的方言 -->
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<!-- ==========可选配置========= -->
<!-- 打印sql -->
<property name="hibernate.show_sql">true</property>
<!-- 格式化sql -->
<property name="hibernate.format_sql">true</property>
<!-- 自动创建表 -->
<property name="hibernate.hbm2ddl.auto">update</property>
<!-- 设置事务隔离级别 -->
<!--
1 read uncommitted :脏读、不可重复读、虚读都会发生
2 read committed :解决脏读 (oracle默认)
4 repeatable read :解决脏读和不可重复读(mysql默认)
8 serializable :解决所有问题。串行执行、效率低
-->
<property name="hibernate.connection.isolation">4</property>
<!-- 配置当前线程绑定的Session -->
<!-- 不用session.close() -->
<property name="hibernate.current_session_context_class">thread</property>
<!-- 引入映射 -->
<mapping resource="com/hibernate/domain/Customer.hbm.xml"/>
<mapping resource="com/hibernate/domain/LinkMan.hbm.xml"/>
</session-factory>
</hibernate-configuration>
HibernateUtils.java------------工具类
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
/**
* Hibernate的工具类
*
*/
public class HibernateUtils {
public static final Configuration cfg;
public static final SessionFactory sf;
static{
cfg = new Configuration().configure();
sf = cfg.buildSessionFactory();
}
public static Session openSession(){
return sf.openSession();
}
public static Session getCurrentSession() {
return sf.getCurrentSession();//需要配置
}
}
HibernateDemo1.java-----------测试类
/**
* 一对多的测试类
* @author zhang
*
*/
public class HibernateDemo1 {
@Test
public void demo1() {
Session session=HibernateUtils.getCurrentSession();
Transaction tx=session.beginTransaction();
//创建客户
Customer customer1=new Customer();
customer1.setCust_name("zhang");
Customer customer2=new Customer();
customer2.setCust_name("wang");
//创建联系人
LinkMan linkMan1=new LinkMan();
linkMan1.setLkm_name("aaa");
LinkMan linkMan2=new LinkMan();
linkMan2.setLkm_name("bbb");
LinkMan linkMan3=new LinkMan();
linkMan3.setLkm_name("ccc");
//设置关系
linkMan1.setCustomer(customer1);
linkMan2.setCustomer(customer1);
linkMan3.setCustomer(customer2);
customer1.getLinkMans().add(linkMan1);
customer1.getLinkMans().add(linkMan2);
customer2.getLinkMans().add(linkMan3);
//保存数据
session.save(customer1);//一定要先放customer
session.save(customer2);
session.save(linkMan1);
session.save(linkMan2);
session.save(linkMan3);
tx.commit();
}
}
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