Hibernate（六）：映射一对多关联关系、双向一对多映射

在领域模型中，类与类之间最普通的关系就是关联关系。

在UML中，关联是有方向的：

　　例如：Customer与Order，一个用户能发出多个订单，而一个订单只能属于一个用户。

• 单向关联

　　1）从Order到Customer的关联是多对一关联；

定义Customer：

 package com.dx.hibernate.onetomany;

 public class Customer {
     private Integer customerId;
     private String customerName;

     public Customer() {
     }

     public Customer(String customerName) {
         super();
         this.customerName = customerName;
     }

     public Integer getCustomerId() {
         return customerId;
     }

     public void setCustomerId(Integer customerId) {
         this.customerId = customerId;
     }

     public String getCustomerName() {
         return customerName;
     }

     public void setCustomerName(String customerName) {
         this.customerName = customerName;
     }
 }

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated 2017-5-24 12:02:56 by Hibernate Tools 3.5.0.Final -->
<hibernate-mapping>
    <class name="com.dx.hibernate.onetomany.Customer" table="CUSTOMER">
        <id name="customerId" type="java.lang.Integer">
            <column name="CUSTOMER_ID" />
            <generator class="native" />
        </id>
        <property name="customerName" type="java.lang.String">
            <column name="CUSTOMER_NAME" />
        </property>
    </class>
</hibernate-mapping>

定义Order：

package com.dx.hibernate.onetomany;

public class Order {
    private Integer orderId;
    private String orderName;
    private Customer customer;

    public Integer getOrderId() {
        return orderId;
    }

    public void setOrderId(Integer orderId) {
        this.orderId = orderId;
    }

    public String getOrderName() {
        return orderName;
    }

    public void setOrderName(String orderName) {
        this.orderName = orderName;
    }

    public Customer getCustomer() {
        return customer;
    }

    public void setCustomer(Customer customer) {
        this.customer = customer;
    }
}

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated 2017-5-24 12:02:56 by Hibernate Tools 3.5.0.Final -->
<hibernate-mapping>
    <class name="com.dx.hibernate.onetomany.Order" table="ORDERS">
        <id name="orderId" type="java.lang.Integer">
            <column name="ORDER_ID" />
            <generator class="assigned" />
        </id>
        <property name="orderName" type="java.lang.String">
            <column name="ORDER_NAME" />
        </property>
        <many-to-one name="customer" class="com.dx.hibernate.onetomany.Customer">
            <column name="CUSTOMER_ID" />
        </many-to-one>
    </class>
</hibernate-mapping>

初始化项目时，生成sql语句：

Hibernate: 

create table CUSTOMER (
　　CUSTOMER_ID integer not null auto_increment,
　　CUSTOMER_NAME varchar(255),
　　primary key (CUSTOMER_ID)
) engine=InnoDB
Hibernate: 

create table ORDERS (
　　ORDER_ID integer not null auto_increment,
　　ORDER_NAME varchar(255),
　　CUSTOMER_ID integer,
　　primary key (ORDER_ID)
) engine=InnoDB
Hibernate: 

alter table ORDERS
add constraint FKkdbly1ij6f4kqh378kfne6ilx
foreign key (CUSTOMER_ID)
references CUSTOMER (CUSTOMER_ID)

测试代码1：

package com.dx.hibernate.onetomany;

import static org.junit.Assert.fail;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.Metadata;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.model.naming.ImplicitNamingStrategyComponentPathImpl;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class TestMain {
    private SessionFactory sessionFactory = null;
    private Session session = null;
    private Transaction transaction = null;

    @Before
    public void init() {
        StandardServiceRegistry standardRegistry = new StandardServiceRegistryBuilder().configure().build();
        Metadata metadata = new MetadataSources(standardRegistry).getMetadataBuilder().applyImplicitNamingStrategy(ImplicitNamingStrategyComponentPathImpl.INSTANCE).build();

        sessionFactory = metadata.getSessionFactoryBuilder().build();
        session = sessionFactory.getCurrentSession();
        transaction = session.beginTransaction();
    }

    @Test
    public void test() {
        Customer customer = new Customer("customer1");
        Order order1 = new Order("order1", customer);
        Order order2 = new Order("order2", customer);

        session.save(customer);
        session.save(order1);
        session.save(order2);
    }

    @After
    public void destory() {
        transaction.commit();
        session.close();
        sessionFactory.close();
    }
}

测试执行sql:

Hibernate:
    insert
    into
        CUSTOMER
        (CUSTOMER_NAME)
    values
        (?)
Hibernate:
    insert
    into
        ORDERS
        (ORDER_NAME, CUSTOMER_ID)
    values
        (?, ?)
Hibernate:
    insert
    into
        ORDERS
        (ORDER_NAME, CUSTOMER_ID)
    values
        (?, ?)

测试代码2：

    @Test
    public void test() {
        Order order = (Order) session.get(Order.class, 1);

        System.out.println(order.getOrderName());
        System.out.println(order.getCustomer().getCustomerName());
    }

测试结果：

测试通过，且查询语句为：

Hibernate:
    select
        order0_.ORDER_ID as ORDER_ID1_1_0_,
        order0_.ORDER_NAME as ORDER_NA2_1_0_,
        order0_.CUSTOMER_ID as CUSTOMER3_1_0_
    from
        ORDERS order0_
    where
        order0_.ORDER_ID=?
order1
Hibernate:
    select
        customer0_.CUSTOMER_ID as CUSTOMER1_0_0_,
        customer0_.CUSTOMER_NAME as CUSTOMER2_0_0_
    from
        CUSTOMER customer0_
    where
        customer0_.CUSTOMER_ID=?
customer1

测试代码3：

    @Test
    public void test() {
        Order order = (Order) session.get(Order.class, 1);

        System.out.println(order.getOrderName());
        //System.out.println(order.getCustomer().getCustomerName());

        session.close();

        System.out.println(order.getCustomer().getCustomerName());
    }

测试结果不通过，执行sql语句:

Hibernate:
    select
        order0_.ORDER_ID as ORDER_ID1_1_0_,
        order0_.ORDER_NAME as ORDER_NA2_1_0_,
        order0_.CUSTOMER_ID as CUSTOMER3_1_0_
    from
        ORDERS order0_
    where
        order0_.ORDER_ID=?
order1

测试4：

修改Order.hbm.xml

        <many-to-one name="customer" class="com.dx.hibernate.onetomany.Customer" fetch="join">
            <column name="CUSTOMER_ID" />
        </many-to-one>

测试代码：

         Order order = (Order) session.get(Order.class, 1);

         System.out.println(order.getOrderName());
         System.out.println(order.getCustomer().getCustomerName());

测试通过，打印的sql语句：

Hibernate:
    select
        order0_.ORDER_ID as ORDER_ID1_1_0_,
        order0_.ORDER_NAME as ORDER_NA2_1_0_,
        order0_.CUSTOMER_ID as CUSTOMER3_1_0_,
        customer1_.CUSTOMER_ID as CUSTOMER1_0_1_,
        customer1_.CUSTOMER_NAME as CUSTOMER2_0_1_
    from
        ORDERS order0_
    left outer join
        CUSTOMER customer1_
            on order0_.CUSTOMER_ID=customer1_.CUSTOMER_ID
    where
        order0_.ORDER_ID=?

测试代码5：

修改Order.hbm.xml

        <many-to-one name="customer" class="com.dx.hibernate.onetomany.Customer" fetch="join">
            <column name="CUSTOMER_ID" />
        </many-to-one>

测试代码：

         Order order = (Order) session.get(Order.class, 1);

         System.out.println(order.getOrderName());
         System.out.println(order.getCustomer().getCustomerName());

         session.close();

         System.out.println(order.getCustomer().getCustomerName());

测试不通过。

　　2）从Customer到Order的关联是一对多关联。

Order.java

 package com.dx.hibernate.onetomany;

 public class Order {
     private Integer orderId;
     private String orderName;

     public Order() {
         super();
     }

     public Order(String orderName) {
         super();
         this.orderName = orderName;
     }

     public Integer getOrderId() {
         return orderId;
     }

     public void setOrderId(Integer orderId) {
         this.orderId = orderId;
     }

     public String getOrderName() {
         return orderName;
     }

     public void setOrderName(String orderName) {
         this.orderName = orderName;
     }

 }

Order.hbm.xml

 <?xml version="1.0"?>
 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 <!-- Generated 2017-5-25 22:09:21 by Hibernate Tools 3.5.0.Final -->
 <hibernate-mapping>
     <class name="com.dx.hibernate.onetomany.Order" table="ORDERS">
         <id name="orderId" type="java.lang.Integer">
             <column name="ORDER_ID" />
             <generator class="native" />
         </id>
         <property name="orderName" type="java.lang.String">
             <column name="ORDER_NAME" />
         </property>
     </class>
 </hibernate-mapping>

Customer.java

 package com.dx.hibernate.onetomany;

 import java.util.ArrayList;
 import java.util.List;

 public class Customer {
     private Integer customerId;
     private String customerName;
     private List<Order> orders = new ArrayList<Order>();

     public Customer() {
     }

     public Customer(String customerName) {
         super();
         this.customerName = customerName;
     }

     public Integer getCustomerId() {
         return customerId;
     }

     public void setCustomerId(Integer customerId) {
         this.customerId = customerId;
     }

     public String getCustomerName() {
         return customerName;
     }

     public void setCustomerName(String customerName) {
         this.customerName = customerName;
     }

     public List<Order> getOrders() {
         return orders;
     }

     public void setOrders(List<Order> orders) {
         this.orders = orders;
     }
 }

Customer.hbm.xml

 <?xml version="1.0"?>
 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 <!-- Generated 2017-5-25 22:09:21 by Hibernate Tools 3.5.0.Final -->
 <hibernate-mapping>
     <class name="com.dx.hibernate.onetomany.Customer" table="CUSTOMER">
         <id name="customerId" type="java.lang.Integer">
             <column name="CUSTOMER_ID" />
             <generator class="native" />
         </id>
         <property name="customerName" type="java.lang.String">
             <column name="CUSTOMER_NAME" />
         </property>
         <list name="orders" inverse="false" table="ORDERS" lazy="true">
             <key>
                 <column name="CUSTOMER_ID" />
             </key>
             <list-index></list-index>
             <one-to-many class="com.dx.hibernate.onetomany.Order" />
         </list>
     </class>
 </hibernate-mapping>

TestMain.java

package com.dx.hibernate.onetomany;

import static org.junit.Assert.fail;

import java.util.List;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.Metadata;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.model.naming.ImplicitNamingStrategyComponentPathImpl;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.query.Query;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class TestMain {
    private SessionFactory sessionFactory = null;
    private Session session = null;
    private Transaction transaction = null;

    @Before
    public void init() {
        StandardServiceRegistry standardRegistry = new StandardServiceRegistryBuilder().configure().build();
        Metadata metadata = new MetadataSources(standardRegistry).getMetadataBuilder().applyImplicitNamingStrategy(ImplicitNamingStrategyComponentPathImpl.INSTANCE).build();

        sessionFactory = metadata.getSessionFactoryBuilder().build();
        session = sessionFactory.getCurrentSession();
        transaction = session.beginTransaction();
    }

    @SuppressWarnings("deprecation")
    @Test
    public void test() {
         Order order1 = new Order("order1");
         Order order2 = new Order("order2");
         Customer customer = new Customer("customer1");
         customer.getOrders().add(order1);
         customer.getOrders().add(order2);

         session.save(customer);
         session.save(order1);
         session.save(order2);

        Customer customerFetch = (Customer) session.get(Customer.class, 1);

        System.out.println(customerFetch.getCustomerName());
        System.out.println(customerFetch.getOrders().size());

    }

    @After
    public void destory() {
        transaction.commit();
        session.close();
        sessionFactory.close();
    }
}

测试结果：通过，打印信息如下：

INFO: HHH10001501: Connection obtained from JdbcConnectionAccess [org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$ConnectionProviderJdbcConnectionAccess@320e400] for (non-JTA) DDL execution was not in auto-commit mode; the Connection 'local transaction' will be committed and the Connection will be set into auto-commit mode.
Hibernate: 

    create table CUSTOMER (
       CUSTOMER_ID integer not null auto_increment,
        CUSTOMER_NAME varchar(255),
        primary key (CUSTOMER_ID)
    ) engine=InnoDB
Hibernate: 

    create table ORDERS (
       ORDER_ID integer not null auto_increment,
        ORDER_NAME varchar(255),
        CUSTOMER_ID integer,
        orders_ORDER integer,
        primary key (ORDER_ID)
    ) engine=InnoDB
Hibernate: 

    alter table ORDERS
       add constraint FKkdbly1ij6f4kqh378kfne6ilx
       foreign key (CUSTOMER_ID)
       references CUSTOMER (CUSTOMER_ID)
Hibernate:
    insert
    into
        CUSTOMER
        (CUSTOMER_NAME)
    values
        (?)
Hibernate:
    insert
    into
        ORDERS
        (ORDER_NAME)
    values
        (?)
Hibernate:
    insert
    into
        ORDERS
        (ORDER_NAME)
    values
        (?)
customer1
2
Hibernate:
    update
        ORDERS
    set
        CUSTOMER_ID=?,
        orders_ORDER=?
    where
        ORDER_ID=?
Hibernate:
    update
        ORDERS
    set
        CUSTOMER_ID=?,
        orders_ORDER=?
    where
        ORDER_ID=?

• 双向关联

Order.java

 package com.dx.hibernate.onetomany;

 public class Order {
     private Integer orderId;
     private String orderName;
     private Customer customer;

     public Order() {
         super();
     }

     public Order(String orderName) {
         super();
         this.orderName = orderName;
     }

     public Integer getOrderId() {
         return orderId;
     }

     public void setOrderId(Integer orderId) {
         this.orderId = orderId;
     }

     public String getOrderName() {
         return orderName;
     }

     public void setOrderName(String orderName) {
         this.orderName = orderName;
     }

     public Customer getCustomer() {
         return customer;
     }

     public void setCustomer(Customer customer) {
         this.customer = customer;
     }

 }

Order.hbm.xml

 <?xml version="1.0"?>
 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 <!-- Generated 2017-5-25 22:09:21 by Hibernate Tools 3.5.0.Final -->
 <hibernate-mapping>
     <class name="com.dx.hibernate.onetomany.Order" table="ORDERS">
         <id name="orderId" type="java.lang.Integer">
             <column name="ORDER_ID" />
             <generator class="native" />
         </id>
         <property name="orderName" type="java.lang.String">
             <column name="ORDER_NAME" />
         </property>
         <many-to-one name="customer" class="com.dx.hibernate.onetomany.Customer" lazy="proxy">
             <column name="CUSTOMER_ID"></column>
         </many-to-one>
     </class>
 </hibernate-mapping>

Customer.java

 package com.dx.hibernate.onetomany;

 import java.util.ArrayList;
 import java.util.List;

 public class Customer {
     private Integer customerId;
     private String customerName;
     private List<Order> orders = new ArrayList<Order>();

     public Customer() {
     }

     public Customer(String customerName) {
         super();
         this.customerName = customerName;
     }

     public Integer getCustomerId() {
         return customerId;
     }

     public void setCustomerId(Integer customerId) {
         this.customerId = customerId;
     }

     public String getCustomerName() {
         return customerName;
     }

     public void setCustomerName(String customerName) {
         this.customerName = customerName;
     }

     public List<Order> getOrders() {
         return orders;
     }

     public void setOrders(List<Order> orders) {
         this.orders = orders;
     }
 }

Customer.hbm.xml

 <?xml version="1.0"?>
 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 <!-- Generated 2017-5-25 22:09:21 by Hibernate Tools 3.5.0.Final -->
 <hibernate-mapping>
     <class name="com.dx.hibernate.onetomany.Customer" table="CUSTOMER">
         <id name="customerId" type="java.lang.Integer">
             <column name="CUSTOMER_ID" />
             <generator class="native" />
         </id>
         <property name="customerName" type="java.lang.String">
             <column name="CUSTOMER_NAME" />
         </property>
         <list name="orders" inverse="false" table="ORDERS" lazy="true">
             <key>
                 <column name="CUSTOMER_ID" />
             </key>
             <list-index></list-index>
             <one-to-many class="com.dx.hibernate.onetomany.Order" />
         </list>
     </class>
 </hibernate-mapping>

测试1

 package com.dx.hibernate.onetomany;

 import static org.junit.Assert.fail;

 import java.util.List;

 import org.hibernate.Session;
 import org.hibernate.SessionFactory;
 import org.hibernate.Transaction;
 import org.hibernate.boot.Metadata;
 import org.hibernate.boot.MetadataSources;
 import org.hibernate.boot.model.naming.ImplicitNamingStrategyComponentPathImpl;
 import org.hibernate.boot.registry.StandardServiceRegistry;
 import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
 import org.hibernate.query.Query;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;

 public class TestMain {
     private SessionFactory sessionFactory = null;
     private Session session = null;
     private Transaction transaction = null;

     @Before
     public void init() {
         StandardServiceRegistry standardRegistry = new StandardServiceRegistryBuilder().configure().build();
         Metadata metadata = new MetadataSources(standardRegistry).getMetadataBuilder().applyImplicitNamingStrategy(ImplicitNamingStrategyComponentPathImpl.INSTANCE).build();

         sessionFactory = metadata.getSessionFactoryBuilder().build();
         session = sessionFactory.getCurrentSession();
         transaction = session.beginTransaction();
     }

     @SuppressWarnings("deprecation")
     @Test
     public void test() {
          Order order1 = new Order("order1");
          Order order2 = new Order("order2");
          Customer customer = new Customer("customer1");
          customer.getOrders().add(order1);
          customer.getOrders().add(order2);

          session.save(customer);
          session.save(order1);
          session.save(order2);

         Customer customerFetch = (Customer) session.get(Customer.class, 1);

         System.out.println(customerFetch.getCustomerName());
         System.out.println(customerFetch.getOrders().size());

     }

     @After
     public void destory() {
         transaction.commit();
         session.close();
         sessionFactory.close();
     }
 }

测试打印信息：

Hibernate: 

    create table CUSTOMER (
       CUSTOMER_ID integer not null auto_increment,
        CUSTOMER_NAME varchar(255),
        primary key (CUSTOMER_ID)
    ) engine=InnoDB
Hibernate: 

    create table ORDERS (
       ORDER_ID integer not null auto_increment,
        ORDER_NAME varchar(255),
        CUSTOMER_ID integer,
        orders_ORDER integer,
        primary key (ORDER_ID)
    ) engine=InnoDB
Hibernate: 

    alter table ORDERS
       add constraint FKkdbly1ij6f4kqh378kfne6ilx
       foreign key (CUSTOMER_ID)
       references CUSTOMER (CUSTOMER_ID)
Hibernate:
    insert
    into
        CUSTOMER
        (CUSTOMER_NAME)
    values
        (?)
Hibernate:
    insert
    into
        ORDERS
        (ORDER_NAME, CUSTOMER_ID)
    values
        (?, ?)
Hibernate:
    insert
    into
        ORDERS
        (ORDER_NAME, CUSTOMER_ID)
    values
        (?, ?)
customer1
2
Hibernate:
    update
        ORDERS
    set
        CUSTOMER_ID=?,
        orders_ORDER=?
    where
        ORDER_ID=?
Hibernate:
    update
        ORDERS
    set
        CUSTOMER_ID=?,
        orders_ORDER=?
    where
        ORDER_ID=?

测试2：

    @Test
    public void testUpdate(){
        Customer customerFetch = (Customer) session.get(Customer.class, 1);
        customerFetch.getOrders().listIterator().next().setOrderName("ABC");
    }

测试输出：

Hibernate:
    select
        customer0_.CUSTOMER_ID as CUSTOMER1_0_0_,
        customer0_.CUSTOMER_NAME as CUSTOMER2_0_0_
    from
        CUSTOMER customer0_
    where
        customer0_.CUSTOMER_ID=?
Hibernate:
    select
        orders0_.CUSTOMER_ID as CUSTOMER3_1_0_,
        orders0_.ORDER_ID as ORDER_ID1_1_0_,
        orders0_.orders_ORDER as orders_O4_0_,
        orders0_.ORDER_ID as ORDER_ID1_1_1_,
        orders0_.ORDER_NAME as ORDER_NA2_1_1_,
        orders0_.CUSTOMER_ID as CUSTOMER3_1_1_
    from
        ORDERS orders0_
    where
        orders0_.CUSTOMER_ID=?
Hibernate:
    update
        ORDERS
    set
        ORDER_NAME=?,
        CUSTOMER_ID=?
    where
        ORDER_ID=?

测试3：

    @Test
    public void testRemove() {
        Customer customerFetch = (Customer) session.get(Customer.class, 2);
        Order order = customerFetch.getOrders().listIterator().next();
        session.remove(order);
    }

测试输出：

Hibernate:
    select
        customer0_.CUSTOMER_ID as CUSTOMER1_0_0_,
        customer0_.CUSTOMER_NAME as CUSTOMER2_0_0_
    from
        CUSTOMER customer0_
    where
        customer0_.CUSTOMER_ID=?
Hibernate:
    select
        orders0_.CUSTOMER_ID as CUSTOMER3_1_0_,
        orders0_.ORDER_ID as ORDER_ID1_1_0_,
        orders0_.orders_ORDER as orders_O4_0_,
        orders0_.ORDER_ID as ORDER_ID1_1_1_,
        orders0_.ORDER_NAME as ORDER_NA2_1_1_,
        orders0_.CUSTOMER_ID as CUSTOMER3_1_1_
    from
        ORDERS orders0_
    where
        orders0_.CUSTOMER_ID=?
Hibernate:
    delete
    from
        ORDERS
    where
        ORDER_ID=?