hibernate 一对多|多对一

一对多：（一个客户对应多个联系人）

　

多的一方维护一的一方的主键作为外键

客户实体：Customer.java

package cn.future.domain;

import java.util.HashSet;
import java.util.Set;

public class Customer {
    
    /*
     * 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;
     */
    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;
    
    //使用set集合表达一对多的关系
    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;
    }
    @Override
    public String toString() {
        return "Customer [cust_id=" + cust_id + ", cust_name=" + cust_name + "]";
    }

}

客户实体对应的映射文件：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="cn.future.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_phone" column="cust_phone" ></property>
        <property name="cust_mobile" column="cust_mobile" ></property>
        
        <!-- 一对多的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Costomer关联的对象完整类名
         -->
        <!-- 
            级联操作：cascade
                save-update:级联保存更新
                delete:级联删除
                all: 上面两个相加
            级联操作：一般情况下是不配置的，要配置也是配置save-update（企业中一般不用这个属性）
         -->
         <!-- 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
          -->
        <set name="linkMans">
            <key column="lkm_cust_id"></key>
            <one-to-many class="LinkMan"></one-to-many>
        </set>
    </class>
</hibernate-mapping>

联系人实体：LinkMan.java

package cn.future.domain;

public class LinkMan {

    /*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;*/
    
    
    private Long lkm_id;
    private String lkm_name;
    private Character 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;
    
    //表达多对一的关系
    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 String getLkm_name() {
        return lkm_name;
    }
    public void setLkm_name(String lkm_name) {
        this.lkm_name = lkm_name;
    }
    public Character getLkm_gender() {
        return lkm_gender;
    }
    public void setLkm_gender(Character 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 String getLkm_position() {
        return lkm_position;
    }
    public void setLkm_position(String lkm_position) {
        this.lkm_position = lkm_position;
    }
    public String getLkm_memo() {
        return lkm_memo;
    }
    public void setLkm_memo(String lkm_memo) {
        this.lkm_memo = lkm_memo;
    }
    
}

联系人实体对应的映射文件：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="cn.future.domain" >
    <class name="LinkMan" table="cst_linkman" >
        <id name="lkm_id"  >
            <generator class="native"></generator>
        </id>
        <property name="lkm_name" column="lkm_name" ></property>
        <property name="lkm_gender" column="lkm_gender" ></property>
        <property name="lkm_phone" column="lkm_phone" ></property>
        <property name="lkm_mobile" column="lkm_mobile" ></property>
        <property name="lkm_email" column="lkm_email" ></property>
        <property name="lkm_qq" column="lkm_qq" ></property>
        <property name="lkm_position" column="lkm_position" ></property>
        <property name="lkm_memo" column="lkm_memo" ></property>
        
        <!-- 多对一的关系在配置文件中配置 -->
        <!-- 
            name属性：引用属性名
            column属性：外键列名
            class属性：与LinkMan关联的对象完整类名
         -->
         <!-- 
            级联操作：cascade
                save-update:级联保存更新
                delete:级联删除
                all: 上面两个相加
            级联操作：一般情况下是不配置的，要配置也是之配置save-update
         -->
        <many-to-one name="customer" column="lkm_cust_id" class="Customer"></many-to-one>
    </class>
</hibernate-mapping>

注意：

　　客户：因为一个客户对应多个联系人，所以在客户数据库表中没有关于联系人的任何字段信息，但是在客户实体类中却维护了联系人的set集合并且在客户的映射文件中也有维护联系人，并注明在联系人表中存放的外键是这个客户的主键，也就是说客户的映射文件自动把客户的cust_id字段对应到联系人表中的lkm_cust_id字段

　　联系人：联系人实体类中存放了对应客户的整个类对象，但在联系人表中却只维护了对应客户的主键（作为外键），联系人的映射文件中也有对这个外键的描述

　　实体类和映射文件中紫色的文字为hibernate对于一对多|多对一的描述

操作：

package cn.future.one2many;


import java.util.Set;

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

import cn.future.domain.Customer;
import cn.future.domain.LinkMan;
import cn.future.utils.HibernateUtils;

public class Demo {

    @Test
    //一对多|多对一关系操作
    public void fun(){
        //1获得session
        Session session = HibernateUtils.openSession();
        //2开启事务
        Transaction ts = session.beginTransaction();
        //3操作
        Customer customer = new Customer();
        customer.setCust_name("Future");
        
        LinkMan linkMan1 = new LinkMan();
        LinkMan linkMan2 = new LinkMan();
        linkMan1.setLkm_name("ms");
        linkMan2.setLkm_name("grf");
        
        //表达一对多的，客户下有多个联系人 （如果客户映射文件中设置inverse="true"）则下面两行代码可以不写
        customer.getLinkMans().add(linkMan1);
        customer.getLinkMans().add(linkMan2);
        //表达多对一，多个联系人对应一个客户
        linkMan1.setCustomer(customer);
        linkMan2.setCustomer(customer);
        
        session.save(customer);
        session.save(linkMan1);
        session.save(linkMan2);
        
        //4提交事务
        ts.commit();
        //5关闭资源
        session.close();
    }
    
    @Test
    //为已知客户增加联系人
    public void fun1(){
        //1获得session
        Session session = HibernateUtils.openSession();
        //2开启事务
        Transaction ts = session.beginTransaction();
        //3操作
        //获得要操作的客户
        Customer customer = session.get(Customer.class, 1l);
        //创建联系人
        LinkMan lk = new LinkMan();
        lk.setLkm_name("home");
        //把联系人添加到客户，将客户设置到联系人中
        customer.getLinkMans().add(lk);
        lk.setCustomer(customer);
        //执行保存操作 （只需要保存联系人，因为现在customer对象是持久化状态，可以直接改变属性，当事务提交和资源关闭的时候会自动保存customer）
        session.save(lk);
        
        //4提交事务
        ts.commit();
        //5关闭资源
        session.close();
    }
    
    @Test
    //为客户删除联系人（相当于把联系人关联的客户外键置空）
    public void fun2(){
        //1获得session
        Session session = HibernateUtils.openSession();
        //2开启事务
        Transaction ts = session.beginTransaction();
        //3操作
        //获得要操作的客户
        Customer customer = session.get(Customer.class, 1l);
        //获取要移除的联系人
        LinkMan lk = session.get(LinkMan.class, 3l);
        //将联系人从客户列表中移除，同时将联系人对应的客户置空
        customer.getLinkMans().remove(lk);
        lk.setCustomer(null);
        
        //4提交事务
        ts.commit();
        //5关闭资源
        session.close();
    }
    
    @Test
    //获取客户下联系人信息
    public void fun3(){
        //1获得session
        Session session = HibernateUtils.openSession();
        //2开启事务
        Transaction ts = session.beginTransaction();
        //3操作
        //获得要操作的客户
        Customer customer = session.get(Customer.class, 1l);
        
        Set<LinkMan> linkMans = customer.getLinkMans();//直接get联系人列表就可以，不用再根据客户的主键查联系人
        
     　　for(LinkMan lk : linkMans){
            System.out.println(lk.getLkm_name());
        }
        //4提交事务
        ts.commit();
        //5关闭资源
        session.close();
    }
}

注意：当一的一方维护了inverse这个属性的时候目的如下图（就是少了update执行语句，一的一方给多的一方赋值外简值用的update语句）

<!-- 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
  -->
<set name="linkMans" inverse="true">
    <key column="lkm_cust_id"></key>
    <one-to-many class="LinkMan"></one-to-many>
</set>

没有inverse这个属性控制台sql执行情况

加了inverse="true"控制台sql执行情况

如果一的一方不需要查找多的一方的list，那么一的一方的实体类不必维护set集合