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.