两个实体类：客户与联系人，一个客户可以有多个联系人
客户类：
package domain;import java.util.HashSet;import java.util.Set;//客户实体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_linkman; ???private String cust_phone; ???private String cust_mobile; ???//使用set集合,表达一对多关系 ???private Set<LinkMan> linkMens = new HashSet<LinkMan>(); ???public Set<LinkMan> getLinkMens() { ???????return linkMens; ???} ???public void setLinkMens(Set<LinkMan> linkMens) { ???????this.linkMens = linkMens; ???} ???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_linkman() { ???????return cust_linkman; ???} ???public void setCust_linkman(String cust_linkman) { ???????this.cust_linkman = cust_linkman; ???} ???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; ???} ???@Override ???public String toString() { ???????return "Customer [cust_id=" + cust_id + ", cust_name=" + cust_name + "]"; ???}}联系人类：
package domain;//联系人实体public class LinkMan { ???private Long lkm_id; ???private Character lkm_gender; ???private String lkm_name; ???private String lkm_phone; ???private String lkm_email; ???private String lkm_qq; ???private String lkm_mobile; ???private String lkm_memo; ???private String lkm_position; ???// 表达多对一关系 ???private Customer customer; ???public Customer getCustomer() { ???????return customer; ???} ???public void setCustomer(Customer customer) { ???????this.customer = customer; ???} ???public Long getLkm_id() { ???????return lkm_id; ???} ???public void setLkm_id(Long lkm_id) { ???????this.lkm_id = lkm_id; ???} ???public Character getLkm_gender() { ???????return lkm_gender; ???} ???public void setLkm_gender(Character lkm_gender) { ???????this.lkm_gender = lkm_gender; ???} ???public String getLkm_name() { ???????return lkm_name; ???} ???public void setLkm_name(String lkm_name) { ???????this.lkm_name = lkm_name; ???} ???public String getLkm_phone() { ???????return lkm_phone; ???} ???public void setLkm_phone(String lkm_phone) { ???????this.lkm_phone = lkm_phone; ???} ???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 String getLkm_mobile() { ???????return lkm_mobile; ???} ???public void setLkm_mobile(String lkm_mobile) { ???????this.lkm_mobile = lkm_mobile; ???} ???public String getLkm_memo() { ???????return lkm_memo; ???} ???public void setLkm_memo(String lkm_memo) { ???????this.lkm_memo = lkm_memo; ???} ???public String getLkm_position() { ???????return lkm_position; ???} ???public void setLkm_position(String lkm_position) { ???????this.lkm_position = lkm_position; ???}}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 package="domain" > ???<class name="Customer" table="cst_customer" > ???????<id name="cust_id" ?> ???????????<generator class="native"></generator> ???????</id> ???????<property name="cust_name" column="cust_name" ></property> ???????<property name="cust_source" column="cust_source" ></property> ???????<property name="cust_industry" column="cust_industry" ></property> ???????<property name="cust_level" column="cust_level" ></property> ???????<property name="cust_linkman" column="cust_linkman" ></property> ???????<property name="cust_phone" column="cust_phone" ></property> ???????<property name="cust_mobile" column="cust_mobile" ></property> ???????????<!-- 集合,一对多关系,在配置文件中配置 --> ???????<!-- ????????????name属性:集合属性名 ???????????column属性: 外键列名 ???????????class属性: 与我关联的对象完整类名 ????????--> ???????<set name="linkMens"> ???????????<key column="lkm_cust_id" ></key> ???????????<one-to-many class="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 package="domain" > ???<class name="LinkMan" table="cst_linkman" > ???????<id name="lkm_id" ?> ???????????<generator class="native"></generator> ???????</id> ???????<property name="lkm_gender" ?></property> ???????<property name="lkm_name" ?></property> ???????<property name="lkm_phone" ?></property> ???????<property name="lkm_email" ?></property> ???????<property name="lkm_qq" ?></property> ???????<property name="lkm_mobile" ?></property> ???????<property name="lkm_memo" ?></property> ???????<property name="lkm_position" ?></property> ???????????????<!-- 多对一 --> ???????<!-- ????????????name属性:引用属性名 ???????????column属性: 外键列名 ???????????class属性: 与我关联的对象完整类名 ????????--> ???????<many-to-one name="customer" column="lkm_cust_id" class="Customer" ?></many-to-one> ???</class></hibernate-mapping>
核心配置文件：
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> ???????<!-- 数据库驱动 --> ???????<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> ???????<!-- 数据库url --> ???????<property name="hibernate.connection.url">jdbc:mysql:///hibernate</property> ???????<!-- 数据库连接用户名 --> ???????<property name="hibernate.connection.username">root</property> ???????<!-- 数据库连接密码 --> ???????<property name="hibernate.connection.password">xuyiqing</property> ???????????????<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> ???????<!-- 将hibernate生成的sql语句打印到控制台 --> ???????<property name="hibernate.show_sql">true</property> ???????<!-- 将hibernate生成的sql语句格式化(语法缩进) --> ???????<property name="hibernate.format_sql">true</property> ???????????????<property name="hibernate.hbm2ddl.auto">update</property> ???????<!-- 引入orm元数据 路径书写: 填写src下的路径 --> ???????????????<property name="hibernate.connection.isolation">4</property> ????????????????<!-- 指定session与当前线程绑定 --> ???????<property name="hibernate.current_session_context_class">thread</property> ???????????????<mapping resource="domain/Customer.hbm.xml" /> ???????<mapping resource="domain/LinkMan.hbm.xml" /> ???</session-factory></hibernate-configuration>
自定义工具类：
package utils;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.cfg.Configuration;public class HibernateUtils { ???private static SessionFactory sf; ???????static{ ???????//1 创建,调用空参构造 ???????Configuration conf = new Configuration().configure(); ???????//2 根据配置信息,创建 SessionFactory对象 ????????sf = conf.buildSessionFactory(); ???} ???????//获得session => 获得全新session ???public static Session openSession(){ ???????????????//3 获得session ???????????????Session session = sf.openSession(); ???????????????????????????????return session; ???????????} ???//获得session => 获得与线程绑定的session ???public static Session getCurrentSession(){ ???????//3 获得session ???????Session session = sf.getCurrentSession(); ???????????????return session; ???} ???}测试类：
package oneTomany;import org.hibernate.Session;import org.hibernate.Transaction;import org.junit.Test;import domain.Customer;import domain.LinkMan;import utils.HibernateUtils;//一对多|多对一关系操作public class Demo { ???@Test ???//保存客户 以及客户 下的联系人 ???public void fun1(){ ???????//1 获得session ???????Session session = HibernateUtils.openSession(); ???????//2 开启事务 ???????Transaction tx = session.beginTransaction(); ???????//------------------------------------------------- ???????//3操作 ???????Customer c = new Customer(); ???????c.setCust_name("腾讯"); ???????????????LinkMan lm1 = new LinkMan(); ???????lm1.setLkm_name("马化腾"); ???????????????LinkMan lm2 = new LinkMan(); ???????lm2.setLkm_name("张三"); ???????????????//表达一对多,客户下有多个联系人 ???????c.getLinkMens().add(lm1); ???????c.getLinkMens().add(lm2); ???????????????//表达多对一,联系人属于哪个客户 ???????lm1.setCustomer(c); ???????lm2.setCustomer(c); ???????????????????????session.save(c); ???????session.save(lm1); ???????session.save(lm2); ???????//------------------------------------------------- ???????//4提交事务 ???????tx.commit(); ???????//5关闭资源 ???????session.close(); ???} ???????@Test ???//为客户增加联系人 ???public void fun2(){ ???????//1 获得session ???????Session session = HibernateUtils.openSession(); ???????//2 开启事务 ???????Transaction tx = session.beginTransaction(); ???????//------------------------------------------------- ???????//3操作 ???????//1> 获得要操作的客户对象 ???????Customer c = session.get(Customer.class,1l); ???????//2> 创建联系人 ???????LinkMan lm1 = new LinkMan(); ???????lm1.setLkm_name("李四"); ???????//3> 将联系人添加到客户,将客户设置到联系人中 ???????c.getLinkMens().add(lm1); ???????lm1.setCustomer(c); ???????//4> 执行保存 ???????session.save(lm1); ???????//------------------------------------------------- ???????//4提交事务 ???????tx.commit(); ???????//5关闭资源 ???????session.close(); ???} ???????@Test ???//为客户删除联系人 ???public void fun3(){ ???????//1 获得session ???????Session session = HibernateUtils.openSession(); ???????//2 开启事务 ???????Transaction tx = session.beginTransaction(); ???????//------------------------------------------------- ???????//3操作 ???????//1> 获得要操作的客户对象 ???????Customer c = session.get(Customer.class,1l); ???????//2> 获得要移除的联系人 ???????LinkMan lm = session.get(LinkMan.class, 3l); ???????//3> 将联系人从客户集合中移除 ???????c.getLinkMens().remove(lm); ???????lm.setCustomer(null); ???????//------------------------------------------------- ???????//4提交事务 ???????tx.commit(); ???????//5关闭资源 ???????session.close(); ???} ???????}进阶操作一：cascade
上边fun1代码这一段：
???????session.save(c); ???????session.save(lm1); ???????session.save(lm2);
这里发现：如果有很多个联系人，依次保存联系人代码量大，有没有一种方法，在保存客户的同时保存所有的联系人呢？
级联操作: cascade
save-update: 级联保存更新
delete:级联删除
all:save-update+delete
级联操作: 简化操作.目的就是为了少些两行代码.
配置文件：
???????<set name="linkMens" cascade="save-update" ?> ???????????<key column="lkm_cust_id" ></key> ???????????<one-to-many class="LinkMan" /> ???????</set>
这里就做到了级联保存
同样还有级联删除：删除客户，那么所有该客户所有联系人都将被删除
注意：客户和联系人配置文件都可以设置cascade属性
进阶操作二：
关系维护属性：inverse
多表操作的时候，会自动维护双方，影响效率，这里可以取消其中的维护以提高效率
在这里，客户一方可以不维护（即设置该属性为true）
???????<set name="linkMens" inverse="true" cascade="delete" ?> ???????????<key column="lkm_cust_id" ></key> ???????????<one-to-many class="LinkMan" /> ???????</set>
inverse属性: 配置关系是否维护.
?true: customer不维护关系
?false(默认值): customer维护关系
?
?inverse属性: 性能优化.提高关系维护的性能.
?原则: 无论怎么放弃,总有一方必须要维护关系.
注意：
一对多关系中: 一的一方放弃.也只能一的一方放弃.多的一方不能放弃.
hibernate框架学习笔记8：一对多关系案例
原文地址：https://www.cnblogs.com/xuyiqing/p/8453165.html