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Rhythmk 学习 Hibernate 05 - Hibernate 表间关系 [ManyToOne,OneToMany]

2024-07-02 15:00:58   219人阅读

1、项目结构：

     

1.1、场景说明: 一个订单，包含多个产品

1.2、类文件：

    Order.java 

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package com.rhythmk.model;
 
import java.util.Date;
 
public class Order {
    public int getOrderID() {
        return orderID;
    }
 
    public void setOrderID(int orderID) {
        this.orderID = orderID;
    }
 
    public String getName() {
        return Name;
    }
 
    public void setName(String name) {
        Name = name;
    }
 
    public double getSumMoney() {
        return SumMoney;
    }
 
    public void setSumMoney(double sumMoney) {
        SumMoney = sumMoney;
    }
 
    public Date getCreateDate() {
        return createDate;
    }
 
    public void setCreateDate(Date createDate) {
        this.createDate = createDate;
    }
 
    private  int  orderID;
    private String  Name;
    private double SumMoney;
     
    @Override
    public String toString() {
        return "Order [orderID=" + orderID + ", Name=" + Name + ", SumMoney="
                + SumMoney + ", createDate=" + createDate + "]";
    }
 
    private Date createDate;
     
}

　order.hbm.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
    <class name="com.rhythmk.model.Order" table="t_order">
        <id name="orderID" type="int">
            <column name="orderID" />
            <generator class="native" />
        </id>
        <property name="Name" type="string">
            <column name="Name" not-null="true" />
        </property>
       <property name="SumMoney" type="double"></property>
        <property name="createDate" type="timestamp">
            <column name="createDate" not-null="true" />
        </property>
     
    </class>
</hibernate-mapping>

    Product.java

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package com.rhythmk.model;
 
public class Product {
    public int getProductID() {
        return productID;
    }
 
    public void setProductID(int productID) {
        this.productID = productID;
    }
 
    public String getProductName() {
        return productName;
    }
 
    public void setProductName(String productName) {
        this.productName = productName;
    }
 
    private int productID;
    private String productName;
     
    public Order getOrder() {
        return order;
    }
 
    public void setOrder(Order order) {
        this.order = order;
    }
 
    private Order order ;
 
    @Override
    public String toString() {
        return "Product [productID=" + productID + ", productName="
                + productName + ", order=" + order + "]";
    }
     
}

　　product.hbm.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
    <class name="com.rhythmk.model.Product" table="t_product">
        <id name="productID" type="int">
            <column name="productID" />
            <generator class="native" />
        </id>
        <property name="productName" type="string">
            <column name="productName"  />
        </property>
           <many-to-one name="order"   column="orderID"></many-to-one> 
     
    </class>
</hibernate-mapping>

hibernate.cfg.xml

<?xml version=‘1.0‘ encoding=‘UTF-8‘?>
<!DOCTYPE hibernate-configuration PUBLIC
          "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
          "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<!-- Generated by MyEclipse Hibernate Tools.                   -->
<hibernate-configuration>

    <session-factory>
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/hibernate_demo</property>
        <property name="connection.username">root</property>
        <property name="connection.password">wangkun</property>
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="myeclipse.connection.profile">com.mysql.jdbc.Driver</property>
        <!--是否在后台显示Hibernate用到的SQL语句，开发时设置为true，便于差错，程序运行时可以在Eclipse的控制台显示Hibernate的执行Sql语句。项目部署后可以设置为false，提高运行效率 -->
        <property name="hibernate.show_sql">true </property>
        <property name="hibernate.hbm2ddl.auto">update</property>
        
          <mapping  resource="com/rhythmk/model/user.hbm.xml" />
         <mapping  resource="com/rhythmk/model/product.hbm.xml" /> 
          <mapping resource="com/rhythmk/model/order.hbm.xml" />
    </session-factory>

</hibernate-configuration>

 

1.3  、结论：

        在Many方 定义XML配置  ：

      <many-to-one name="order"   column="orderID"></many-to-one>

   写入数据调用session.save方法跟单表保存基本一致。

   读取数据：获取Many对象，默认 One对象都是以延迟加载模式进行加载。

    不论是删除 Many ,还是删除 One 对象 都只删除本身数据 ，并非删除全部主从数据，如果删除One对象，一旦Many还有关联One的对象的存在，则将抛出异常。见(test04_del)

 1.4  、测试验证:

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@Test
    public void test02_add() {
        Session session = null;
        try {
            session = HibernateUtil.getSessionFactory().openSession();
            session.beginTransaction();
            Order order = new Order();
            order.setCreateDate(new Date());
            order.setName("订单一");
            order.setSumMoney(12);
            session.save(order);
 
            Product p1 = new Product();
            p1.setOrder(order);
            p1.setProductName("产品1");
            session.save(p1);
 
            Product p2 = new Product();
            p2.setOrder(order);
            p2.setProductName("产品2");
            session.save(p2);
 
            session.getTransaction().commit();
 
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (session != null)
                session.close();
        }
    }

　　输出：

Hibernate: insert into t_order (Name, SumMoney, createDate) values (?, ?, ?)
Hibernate: insert into t_product (productName, orderID) values (?, ?)
Hibernate: insert into t_product (productName, orderID) values (?, ?)

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@Test
public void test03_load() {
    Session session = null;
    try {
        session = HibernateUtil.getSessionFactory().openSession();
        Order order = (Order) session.load(Order.class, 1);
        System.out.println(order);
        System.out.println("-----------Read  Product-----------");
        Product product = (Product) session.load(Product.class, 1);
        System.out.println("-----------Print  Product-----------");
        System.out.println(product);
        System.out.println("-----------Read  Order-----------");
        System.out.println(product.getOrder().getName());
 
 
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (session != null)
            session.close();
    }
}

　　

输出：

Hibernate: select order0_.orderID as orderID1_0_0_, order0_.Name as Name2_0_0_, order0_.SumMoney as SumMoney3_0_0_, order0_.createDate as createDa4_0_0_ from t_order order0_ where order0_.orderID=?
Order [orderID=1, Name=订单一, SumMoney=12.0, createDate=2014-05-02 15:24:02.0]
-----------Read Product-----------
-----------Print Product-----------
Hibernate: select product0_.productID as productI1_1_0_, product0_.productName as productN2_1_0_, product0_.orderID as orderID3_1_0_ from t_product product0_ where product0_.productID=?
Product [productID=1, productName=产品1, order=Order [orderID=1, Name=订单一, SumMoney=12.0, createDate=2014-05-02 15:24:02.0]]
-----------Read Order-----------
订单一

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@Test
public void test04_Get() {
    Session session = null;
    try {
        session = HibernateUtil.getSessionFactory().openSession();
     
        System.out.println("-----------Read  Product-----------");
        Product product = (Product) session.get(Product.class, 1);
        System.out.println("-----------Print  Product-----------");
        System.out.println(product);
        System.out.println("-----------Read  Order-----------");
        System.out.println(product.getOrder().getName());
 
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (session != null)
            session.close();
    }
}

　　输出：

-----------Read Product-----------
Hibernate: select product0_.productID as productI1_1_0_, product0_.productName as productN2_1_0_, product0_.orderID as orderID3_1_0_ from t_product product0_ where product0_.productID=?
-----------Print Product-----------
Hibernate: select order0_.orderID as orderID1_0_0_, order0_.Name as Name2_0_0_, order0_.SumMoney as SumMoney3_0_0_, order0_.createDate as createDa4_0_0_ from t_order order0_ where order0_.orderID=?
Product [productID=1, productName=产品1, order=Order [orderID=1, Name=订单一, SumMoney=12.0, createDate=2014-05-02 15:24:02.0]]
-----------Read Order-----------
订单一

  

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@Test
public void test04_Del() {
    Session session = null;
    try {
        session = HibernateUtil.getSessionFactory().openSession();
        session.beginTransaction();
        /*
         
        Product product = (Product) session.get(Product.class, 1);
        session.delete(product);
    输出：
    Hibernate: select product0_.productID as productI1_1_0_, product0_.productName as productN2_1_0_, product0_.orderID as orderID3_1_0_ from t_product product0_ where product0_.productID=?
    Hibernate: delete from t_product where productID=?
    */ 
        Order order = (Order) session.get(Order.class, 3);
        session.delete(order);
         
         
        session.getTransaction().commit();
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (session != null)
            session.close();
    }
}

　　输出：


Hibernate: select order0_.orderID as orderID1_0_0_, order0_.Name as Name2_0_0_, order0_.SumMoney as SumMoney3_0_0_, order0_.createDate as createDa4_0_0_ from t_order order0_ where order0_.orderID=?
Hibernate: delete from t_order where orderID=?
org.hibernate.exception.ConstraintViolationException: could not execute statement
at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:72)
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:126)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:112)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:190)

 

-------------------------------------------------OneToMany----------------------------------------------------------------------------

>>> OneToMany  单相关联

 

 

2.1   

 需求背景：

   每个人都有很多标签：

在User 类中添加：

 

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public Set<Tag> getTags() {
    return tags;
}
public void setTags(Set<Tag> tags) {
    this.tags = tags;
}
private Set<Tag> tags;

 

　　同时 添加 Tag类：

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package com.rhythmk.model;
 
public class Tag {
   public Integer getTagId() {
        return tagId;
    }
    public void setTagId(Integer tagId) {
        this.tagId = tagId;
    }
    public String getTagTitle() {
        return tagTitle;
    }
    public void setTagTitle(String tagTitle) {
        this.tagTitle = tagTitle;
    }
    public Integer getUserID() {
        return userID;
    }
    @Override
    public String toString() {
        return "Tag [tagId=" + tagId + ", tagTitle=" + tagTitle + ", userID="
                + userID + "]";
    }
    public void setUserID(Integer userID) {
        this.userID = userID;
    }
private Integer  tagId;
   private String tagTitle;
   private Integer userID;
}

　　

 

添加User对应XML配置：

 

        <set name="tags">
            <key column="userID"></key>
            <!--   此处需要配置完成的类别-->
            <one-to-many class="com.rhythmk.model.Tag" />
        </set>

 

注意：此处 one-to-many 对应的 class 需要填写类的全路径名称

2.2  验证：

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@Test
    public void test01_add() {
        Session session = null;
        try {
            session = HibernateUtil.getSessionFactory().openSession();
            session.beginTransaction();
            Tag t1 = new Tag();
            t1.setTagTitle("tag1");
 
            Tag t2 = new Tag();
            t2.setTagTitle("tag2");
 
            Set<Tag> tags = new HashSet<Tag>();
            tags.add(t1);
            tags.add(t2);
 
            User entity = new User();
            entity.setUserName("张飞2222");
            entity.setCreateTime(new Date());
 
            entity.setTags(tags);
            session.save(t1);
            session.save(t2);
            session.save(entity);
 
            session.getTransaction().commit();
 
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (session != null)
                session.close();
        }
    }

　　输出：

Hibernate: insert into t_tag (tagTitle) values (?)
Hibernate: insert into t_tag (tagTitle) values (?)
Hibernate: insert into t_user (userName, createTime) values (?, ?)
Hibernate: update t_tag set userID=? where tagId=?
Hibernate: update t_tag set userID=? where tagId=?

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@Test
    public void test02_get() {
        Session session = null;
        try {
            session = HibernateUtil.getSessionFactory().openSession();
            session.beginTransaction();
 
            System.err.println("------01 -----------");
            User entity = (User) session.get(User.class, 6);
            System.err.println("------02 -----------");
            for (Tag t : entity.getTags()) {
                System.out.println(t);
            }
 
            session.getTransaction().commit();
 
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (session != null)
                session.close();
        }
    }

　　

输出：

------01 -----------
Hibernate: select user0_.userID as userID1_3_0_, user0_.userName as userName2_3_0_, user0_.createTime as createTi3_3_0_ from t_user user0_ where user0_.userID=?
------02 -----------
Hibernate: select tags0_.userID as userID3_3_0_, tags0_.tagId as tagId1_2_0_, tags0_.tagId as tagId1_2_1_, tags0_.tagTitle as tagTitle2_2_1_ from t_tag tags0_ where tags0_.userID=?
Tag [tagId=2, tagTitle=tag1, userID=null]
Tag [tagId=3, tagTitle=tag2, userID=null]

 

 >>> OneToMany  双相关联

背景：一个标签下有多少人

调整原标签代码：

 

      <set name="users">
            <key column="tagId"></key>
            <!--   此处需已在hibernate-mapping   上配置了 类包名-->
            <one-to-many class="User" />
        </set>

 

one-to-many  class仅填写类名 现将包名调整到 hibernate-mapping属性上 如：

<hibernate-mapping  package="com.rhythmk.model">

调整 Tag.java,添加：

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public Set<User> getUsers() {
    return users;
}
 
public void setUsers(Set<User> users) {
    this.users = users;
}
 
private Set<User> users;

测试：

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@Test
    public void test01_add() {
        Session session = null;
        try {
            session = HibernateUtil.getSessionFactory().openSession();
            session.beginTransaction();
            Tag t1 = new Tag();
            t1.setTagTitle("tag1");
 
            Tag t2 = new Tag();
            t2.setTagTitle("tag2");
 
            Set<Tag> tags = new HashSet<Tag>();
            tags.add(t1);
            tags.add(t2);
 
            User u1 = new User();
            u1.setUserName("张飞2222");
            u1.setCreateTime(new Date());
            u1.setTags(tags);
 
            User u2 = new User();
            u2.setUserName("张飞2333332");
            u2.setCreateTime(new Date());
            u2.setTags(tags);
 
            Set<User> users = new HashSet<User>();
            users.add(u1);
            users.add(u2);
 
            t1.setUsers(users);
 
            t2.setUsers(users);
 
            session.save(t1);
            session.save(t2);
            session.save(u1);
            session.save(u2);
            session.getTransaction().commit();
 
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (session != null)
                session.close();
        }
    }

　　输出：

 

　　

Hibernate: insert into t_tag (tagTitle) values (?)
Hibernate: insert into t_tag (tagTitle) values (?)
Hibernate: insert into t_user (userName, createTime) values (?, ?)
Hibernate: insert into t_user (userName, createTime) values (?, ?)
Hibernate: update t_user set tagId=? where userID=?
Hibernate: update t_user set tagId=? where userID=?
Hibernate: update t_user set tagId=? where userID=?
Hibernate: update t_user set tagId=? where userID=?
Hibernate: update t_tag set userID=? where tagId=?
Hibernate: update t_tag set userID=? where tagId=?
Hibernate: update t_tag set userID=? where tagId=?
Hibernate: update t_tag set userID=? where tagId=?

注意：此处因为在提交事务过程中 Tag 以及User都相互影响变化，故出现12条SQL。

   在实际项目中 我们并非需要 One 跟 Many都同时去维护数据，故引入 inverse，当inverse="true" 则不去维护对应关系，现修改User.hbm.xml  如下：

<set name="tags"  lazy="extra"  inverse="true">
            <key column="userID"></key>
            <!--   此处需要配置完成的类别-->
            <one-to-many class="com.rhythmk.model.Tag" />
        </set>

执行测试输出：

Hibernate: insert into t_tag (tagTitle) values (?)
Hibernate: insert into t_tag (tagTitle) values (?)
Hibernate: insert into t_user (userName, createTime) values (?, ?)
Hibernate: insert into t_user (userName, createTime) values (?, ?)
Hibernate: update t_user set tagId=? where userID=?
Hibernate: update t_user set tagId=? where userID=?
Hibernate: update t_user set tagId=? where userID=?
Hibernate: update t_user set tagId=? where userID=?

 

 

 

 

 

 

 


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