hibernate实现非主键映射外键双向多对一关系

红太狼 2022-06-05 01:42 161阅读 0赞

**1 many-to-one多对一端加property-ref关联主表的java对应类外键属性：**

*注：property-ref对应的是java类属性，不是表的字段*

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">
    
    <hibernate-mapping package="cn.com.pojo.n21.both.notPK">
        <class name="Order" table="ORDERS_NOPK">
    
            <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="Customer" property-ref="cyId">
                <column name="CUSTOMER_ID"/>  
             </many-to-one>
    
        </class>
    </hibernate-mapping>

Order.java

package cn.com.pojo.n21.both.notPK;
    
    public class Order { 
    
        private Integer orderId;
        private String orderName;
    
        private Customer customer;
    
        public Order() {
            super();
            // TODO Auto-generated constructor stub
        }
    
    
    
        @Override
        public String toString() {
            return "Order [orderId=" + orderId + ", 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;
        }
    }

**2 set一对多端也加property-ref关联主表的java对应类外键属性：**

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">
    
    <hibernate-mapping package="cn.com.pojo.n21.both.notPK">
        <class name="Customer" table="CUSTOMERS_NOPK">
            <id name="id" type="java.lang.Integer">
                <column name="id" />
                <generator class="native" />
            </id>
            <property name="customerName" type="java.lang.String">
                <column name="CUSTOMER_NAME" />
            </property>
    
            <property name="cyId" type="java.lang.Integer">
                <column name="cy_id" not-null="true" unique="true"/>
            </property>
    
            
            
            <set name="orders" table="ORDERS" cascade="delete" inverse="true">
                
                <key column="CUSTOMER_ID" property-ref="cyId"></key>
                
                <one-to-many class="Order"/>
            </set>
        </class>
    </hibernate-mapping>

Customer.java

package cn.com.pojo.n21.both.notPK;
    
    import java.util.HashSet;
    import java.util.Set;
    
    public class Customer { 
    
        private Integer id;
        private Integer cyId;
        private String customerName;
    
        /* * 1 声明集合类型时候，需要用接口类型，因为hibernate在存取集合类型时， * 返回的是hibernate内置的集合类型，而不是javaSE一个标准的集合实现。 * 2 把集合set进行初始化，可以防止发生空指针异常； */
        private Set<Order> orders = new HashSet<>();
        public Customer() {
            super();
            // TODO Auto-generated constructor stub
        }
        public Integer getId() {
            return id;
        }
        public void setId(Integer id) {
            this.id = id;
        }
        public String getCustomerName() {
            return customerName;
        }
        public void setCustomerName(String customerName) {
            this.customerName = customerName;
        }
        public Set<Order> getOrders() {
            return orders;
        }
        public void setOrders(Set<Order> orders) {
            this.orders = orders;
        }
        public Integer getCyId() {
            return cyId;
        }
        public void setCyId(Integer cyId) {
            this.cyId = cyId;
        }
        @Override
        public String toString() {
            return "Customer [id=" + id + ", cyId=" + cyId + ", customerName="
                    + customerName + ", orders=" + orders + "]";
        }
    }

**3 测试：**

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>
            
            <property name="connection.username">root</property>
            <property name="connection.password">123456</property>
            <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
            <property name="connection.url">jdbc:mysql:///hibernate</property>
    
            
            
            <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
            
            <property name="show_sql">true</property>
            
            <property name="format_sql">true</property>
            
            <property name="hbm2ddl.auto">create</property>
            
            <mapping resource="cn/com/pojo/n21/both/notPK/Customer.hbm.xml"/>
            <mapping resource="cn/com/pojo/n21/both/notPK/Order.hbm.xml"/> 
        </session-factory>
    </hibernate-configuration>

Many2OneTest.java

package cn.com.pojo.n21.both.notPK;
    
    import org.hibernate.Session;
    import org.hibernate.SessionFactory;
    import org.hibernate.Transaction;
    import org.hibernate.cfg.Configuration;
    import org.hibernate.service.ServiceRegistry;
    import org.hibernate.service.ServiceRegistryBuilder;
    import org.junit.After;
    import org.junit.Before;
    import org.junit.Test;
    
    public class Many2OneTest {
    
        private SessionFactory sessionFactory;
        private Session session;
        private Transaction transaction;
    
        @Before
        public void init(){
            Configuration configuration = new Configuration().configure();
            ServiceRegistry serviceRegistry = 
                    new ServiceRegistryBuilder().applySettings(configuration.getProperties())
                                                .buildServiceRegistry();
            sessionFactory = configuration.buildSessionFactory(serviceRegistry);
    
            session = sessionFactory.openSession();
            transaction = session.beginTransaction();
        }
    
        @After
        public void destroy(){
            transaction.commit();
            session.close();
            sessionFactory.close();
        }
    
        @Test
        public void tesSave(){
            Customer c = new Customer();
            c.setCyId(102);
            c.setCustomerName("BB");
    
            Order o1 = new Order();
            o1.setOrderName("ORDER-O1");
    
            Order o2 = new Order();
            o2.setOrderName("ORDER-O2");
    
            //设定双向关联关系
            o1.setCustomer(c);
            o2.setCustomer(c);
    
            c.getOrders().add(o1);
            c.getOrders().add(o2);
    
    
            //执行save
            // 先插入1端，再插入多端，3条insert语句,2条update
            // 因为1端和n端都维护关联关系，所以多出2个update
            // 可以在1端的set节点指定inverse=true，使1端放弃维护关联关系，此时不会有update
            // 建议设定set的inverse=true，建议先插入1端再插入多端，不会出现update语句。
            session.save(o1);
            session.save(o2);
            session.save(c);
        }
    }

测试结果：

![这里写图片描述][SouthEast]

![这里写图片描述][SouthEast 1]

![这里写图片描述][SouthEast 2]

[SouthEast]: /images/20220605/30afb693a1ad46e99e61ca714a948d11.png
[SouthEast 1]: /images/20220605/cd76ffd8954c4017b773ea386a42e46e.png
[SouthEast 2]: /images/20220605/cd461f89f9014c9e8ec521af02dafc28.png