Hibernate的一对多关联映射
数据库表与表之间的关系
一对多关系
- 什么样关系属于一对多?
- 一个部门对应多个员工,一个员工只能属于某一个部门。
- 一个客户对应多个联系人,一个联系人只能属于某一个客户。
- 一对多的建表原则:
多对多关系
- 什么样关系属于多对多?
- 一个学生可以选择多门课程,一门课程也可以被多个学生选择。
- 一个用户可以选择多个角色,一个角色也可以被多个用户选择。
- 多对多的建表原则:
一对一关系(了解)
- 什么样关系属于一对一?
- 一个公司只能有一个注册地址,一个注册地址只能被一个公司注册。
- 一对一的建表原则:
Hibernate一对多的关系配置
创建一个项目,引入相应jar包
创建数据库和表
CREATE TABLE `cst_customer` (
`cust_id` bigint(32) NOT NULL AUTO_INCREMENT COMMENT '客户编号(主键)',
`cust_name` varchar(32) NOT 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=1 DEFAULT CHARSET=utf8;
package HibernateDemo01;
import java.util.HashSet;
import java.util.Set;
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;
private Set<LinkMan> linkMans= new HashSet<LinkMan>();
public Set<LinkMan> getLinkMans() {
return linkMans;
}
public void setLinkMans(Set<LinkMan> linkMans) {
this.linkMans = linkMans;
}
public Long getCust_id() {
return cust_id;
}
public void setCust_id(Long 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_source() {
return cust_source;
}
public void setCust_source(String cust_source) {
this.cust_source = cust_source;
}
public String getCust_industry() {
return cust_industry;
}
public void setCust_industry(String cust_industry) {
this.cust_industry = cust_industry;
}
public String getCust_level() {
return cust_level;
}
public void setCust_level(String cust_level) {
this.cust_level = cust_level;
}
public String getCust_phone() {
return cust_phone;
}
public void setCust_phone(String cust_phone) {
this.cust_phone = cust_phone;
}
public String getCust_mobile() {
return cust_mobile;
}
public void setCust_mobile(String cust_mobile) {
this.cust_mobile = cust_mobile;
}
}
package HibernateDemo01;
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 Customer customer;
public Long getLkm_id() {
return lkm_id;
}
public void setLkm_id(Long lkm_id) {
this.lkm_id = lkm_id;
}
public String getLkm_name() {
return lkm_name;
}
public void setLkm_name(String lkm_name) {
this.lkm_name = lkm_name;
}
public String getLkm_gender() {
return lkm_gender;
}
public void setLkm_gender(String lkm_gender) {
this.lkm_gender = lkm_gender;
}
public String getLkm_phone() {
return lkm_phone;
}
public void setLkm_phone(String lkm_phone) {
this.lkm_phone = lkm_phone;
}
public String getLkm_mobile() {
return lkm_mobile;
}
public void setLkm_mobile(String lkm_mobile) {
this.lkm_mobile = lkm_mobile;
}
public String getLkm_email() {
return lkm_email;
}
public void setLkm_email(String lkm_email) {
this.lkm_email = lkm_email;
}
public String getLkm_qq() {
return lkm_qq;
}
public void setLkm_qq(String lkm_qq) {
this.lkm_qq = lkm_qq;
}
public Customer getCustomer() {
return customer;
}
public void setCustomer(Customer customer) {
this.customer = customer;
}
}
创建映射文件
- Customer.hbm.xml(一的一方的映射创建)
<?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>
<!-- 建立类与表的映射 -->
<class name="HibernateDemo01.Customer" table="cst_customer">
<!-- 建立类中的属性与表中的主键对应 --><!-- 建立OID与主键映射 -->
<id name="cust_id" column="cust_id" >
<!-- 主键生成策略 -->
<generator class="native"/>
</id>
<!-- 建立类中的普通的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" cascade="save-update">
<!--
key标签
* column: 多的一方的外键的名称
-->
<key column="lkm_cust_id"></key>
<!--
one-to-many标签
*class :多的一方的全路径
-->
<one-to-many class="HibernateDemo01.LinkMan"/>
</set>
</class>
</hibernate-mapping>
- LinkMan.hbm.xml(多的一方的映射创建)
<?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="HibernateDemo01.LinkMan" table="cst_linkman">
<!-- 建立OID与主键映射 -->
<id name="lkm_id" column="lkm_id">
<!-- 主键生成策略 -->
<generator class="native"/>
</id>
<!-- 建立普通属性与表字段映射 -->
<property name="lkm_name"></property>
<property name="lkm_gender"></property>
<property name="lkm_phone"></property>
<property name="lkm_mobile"></property>
<property name="lkm_email"></property>
<property name="lkm_qq"></property>
<property name="lkm_position"></property>
<property name="lkm_memo"></property>
<!-- 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
* class :一的一方的类全路径
* column :在多的一方表的名称
-->
<many-to-one name="Customer" cascade="save-update" class="HibernateDemo01.Customer" column="lkm_cust_id"></many-to-one>
</class>
</hibernate-mapping>
引入工具类
package hibernate.utils;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
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();
}
}
创建核心配置文件
<?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>
<!-- 连接数据库的基本参数 -->
<property name="hibernate.connection.driver_class">com.mysql.cj.jdbc.Driver</property>
<property name="hibernate.connection.url"> jdbc:mysql://localhost:3306/hibernate01?useSSL=false &serverTimezone=Asia/Shanghai</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.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">create</property>
<!-- 配置C3P0连接池 -->
<property name="connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
<!--在连接池中可用的数据库连接的最少数目 -->
<property name="c3p0.min_size">5</property>
<!--在连接池中所有数据库连接的最大数目 -->
<property name="c3p0.max_size">20</property>
<!--设定数据库连接的过期时间,以秒为单位,
如果连接池中的某个数据库连接处于空闲状态的时间超过了timeout时间,就会从连接池中清除 -->
<property name="c3p0.timeout">120</property>
<!--每3000秒检查所有连接池中的空闲连接 以秒为单位-->
<property name="c3p0.idle_test_period">3000</property>
<!-- 设置事务隔离级别 -->
<property name="hibernate.connection.isolation">4</property>
<!-- 配置当前线程绑定的Session -->
<property name="hibernate.current_session_context_class">thread</property>
<!-- 引入映射 -->
<mapping resource="HibernateDemo01/LinkMan.hbm.xml"/>
<mapping resource="HibernateDemo01/Customer.hbm.xml"/>
</session-factory>
</hibernate-configuration>
编写测试类
public class HibernateDemo01 {
@Test
public void demo1() {
Session session = HibernateUtils.getCurrentSession();
Transaction tx = session.beginTransaction();
Customer customer1= new Customer();
Customer customer2 = new Customer();
customer1.setCust_name("张三");
customer2.setCust_name("李四");
LinkMan linkMan1 = new LinkMan();
linkMan1.setLkm_name("王一");
LinkMan linkMan2 = new LinkMan();
linkMan2.setLkm_name("陈七");
LinkMan linkMan3 = new LinkMan();
linkMan3.setLkm_name("赵六");
linkMan1.setCustomer(customer1);
linkMan1.setCustomer(customer1);
linkMan1.setCustomer(customer2);
customer1.getLinkMans().add(linkMan1);
customer1.getLinkMans().add(linkMan2);
customer2.getLinkMans().add(linkMan3);
session.save(linkMan1);
session.save(linkMan2);
session.save(linkMan3);
session.save(customer1);
session.save(customer2);
tx.commit();
}
Hibernate的一对多相关操作
一对多关系只保存一边是否可以:
@Test
public void demo02() {
Session session = HibernateUtils.getCurrentSession();
Transaction tx = session.beginTransaction();
Customer customer1= new Customer();
customer1.setCust_name("张三");
LinkMan linkMan1 = new LinkMan();
linkMan1.setLkm_name("王一");
linkMan1.setCustomer(customer1);
customer1.getLinkMans().add(linkMan1);
session.save(customer1);
session.save(linkMan1);
tx.commit();
}
一对多的级联操作
- 什么叫做级联
- 级联指的是,操作一个对象的时候,是否会同时操作其关联的对象。
- 级联是有方向性
- 操作一的一方的时候,是否操作到多的一方
- 操作多的一方的时候,是否操作到一的一方
级联保存或更新
- 保存客户级联联系人
@Test
public void demo03() {
Session session = HibernateUtils.getCurrentSession();
Transaction tx = session.beginTransaction();
Customer customer = new Customer();
customer.setCust_name("张三");
LinkMan linkMan = new LinkMan();
linkMan.setLkm_name("李四");
customer.getLinkMans().add(linkMan);
linkMan.setCustomer(customer);
session.save(customer);
tx.commit();
}
- 保存联系人级联客户
@Test
public void demo04() {
Session session = HibernateUtils.getCurrentSession();
Transaction tx = session.beginTransaction();
Customer customer = new Customer();
customer.setCust_name("王五");
LinkMan linkMan = new LinkMan();
linkMan.setLkm_name("赵柳");
customer.getLinkMans().add(linkMan);
linkMan.setCustomer(customer);
session.save(linkMan);
tx.commit();
}