Hibernate：级联新增与普通删除

Hibernate：级联新增

案例讲解： 订单和订单项
1.1:订单类：

public class Order {
	private Integer orderId;
 	private String orderNo;
 	//定义一对多的关系时一定需要采用接口方式，不许使用实现类
	//implements java.util.Set  代理实现的是set接口
        private Set<OrderItem> orderItems=new HashSet<OrderItem>();

	public Set<OrderItem> getOrderItems() {
	  return orderItems;
	 }
	 public void setOrderItems(Set<OrderItem> orderItems) {
	  this.orderItems = orderItems;
	 }
	 public Integer getOrderId() {
	  return orderId;
	 }
	 public void setOrderId(Integer orderId) {
	  this.orderId = orderId;
	 }
	 public String getOrderNo() {
	  return orderNo;
	 }
	 public void setOrderNo(String orderNo) {
	  this.orderNo = orderNo;
	 }
}

1.2：订单项类：

public class OrderItem {
	private Integer orderItemId;
	 private Integer productId;
	 private Integer quaneity;
	 private Integer oid;
	 
	 private Order order;
	 
	 public Order getOrder() {
	  return order;
	 }
	 public void setOrder(Order order) {
	  this.order = order;
	 }
	 public Integer getOrderItemId() {
	  return orderItemId;
	 }
	 public void setOrderItemId(Integer orderItemId) {
	  this.orderItemId = orderItemId;
	 }
	 public Integer getProductId() {
	  return productId;
	 }
	 public void setProductId(Integer productId) {
	  this.productId = productId;
	 }
	 public Integer getQuaneity() {
	  return quaneity;
	 }
	 public void setQuaneity(Integer quaneity) {
	  this.quaneity = quaneity;
	 }
	 public Integer getOid() {
	  return oid;
	 }
	 public void setOid(Integer oid) {
	  this.oid = oid;
	 }
}

1.3：order.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>
     <class table="t_hibernate_order" name="com.zking.four.entity.Order">
      <id name="orderId" type="java.lang.Integer" column="order_id ">
       <generator class="increment"></generator>
      </id>
      <property name="orderNo" type="java.lang.String" column="order_no "></property>
      
      <!-- 
      name:实体类的类属性
      cascade:用来配置维护实体类之间的关系所用
      inverse:（inverse="true"）关系交由反方控制    即订单项   因为现在配置的是订单，所以反方是订单项
      （inverse="true"） 关系由自己控制   订单
      lazy="false":立即加载
       -->
      <set name="orderItems" cascade="save-update" inverse="true">
       <!-- 订单项外键 -->
       <key column="oid"></key>
       <!-- 一个订单对应多个订单项 -->
       <one-to-many class="com.zking.four.entity.OrderItem"></one-to-many>
      </set>
     </class>
    </hibernate-mapping>

1.4:oederItem.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>
     <class table="t_hibernate_order_item" name="com.zking.four.entity.OrderItem">
      <id name="orderItemId" type="java.lang.Integer" column="order_item_id ">
       <generator class="increment"></generator>
      </id>
      <property name="productId" type="java.lang.Integer" column="product_id "></property>
      <property name="quaneity" type="java.lang.Integer" column="quantity "></property>
      <!--解决报错方案：-->
      <!-- 第一种加insert=false，update=false -->
      <property name="oid" type="java.lang.Integer" column="oid" insert="false" update="false"></property>
      <!-- 第二种加insert=false，update=false -->
      <!-- <property name="oid" type="java.lang.Integer" column="oid"></property> -->
      <!-- 多对一 
      order：orderItem里的属性，也是实体类
      oid：实体类的属性所对应的后台的字段
         -->
      <!-- 会报错 :解决方法：第一种加，第二种加-->
      <!-- 第一种加insert=false，update=false -->
     <many-to-one name="order" class="com.zking.four.entity.Order" column="oid"></many-to-one>
     <!-- 第二种加insert=false，update=false -->
     <!-- <many-to-one name="order" class="com.zking.four.entity.Order" column="oid" insert="false" update="false"></many-to-one> -->
     </class>	     	     	     
</hibernate-mapping>

1.5：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>
	<!-- 1. 数据库相关 -->
	  <property name="connection.username">root</property>
	  <property name="connection.password">123</property>
	  <property name="connection.url">jdbc:mysql://localhost:3306/test?useUnicode=true&amp;characterEncoding=UTF-8</property>
	  <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
	  <!-- 连接MySQL数据库 -->
	  <property name="dialect">org.hibernate.dialect.MySQLDialect</property> 
	  <!-- 连接Oracle数据库 -->
	  <!-- <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property> -->
	  <!-- 2.配置本地事务（No CurrentSessionContext configured!） -->
	  <property name="hibernate.current_session_context_class">thread</property>
	  <!-- 3. 调试相关 -->
	  <property name="show_sql">true</property>
	  <property name="format_sql">true</property>
	  <!-- 4.hibernate需要管理的数据库表对应的实体类映射文件 -->
	  <!-- 级联查询 -->
	  <mapping resource="com/zking/four/entity/order.hbm.xml"></mapping>
	  <mapping resource="com/zking/four/entity/orderItem.hbm.xml"></mapping>
	   </session-factory>
</hibernate-configuration>

1.6：dao方法：

public class OrderDao {
	  //新增订单项
	  public Integer addOrderItem(OrderItem orderItem) {
	  Session session = SessionFactoryUtils.getSession();
	  Transaction transaction = session.beginTransaction();
	  Integer otid =(Integer) session.save(orderItem);
	  transaction.commit();
	  session.close();
	  return otid;
	 }
}

1.7：junit测试：

public class OrderDaoTest {
 private OrderDao orderDao=new OrderDao();
 private OrderItem orderItem=new OrderItem();
 private Order order=new Order();
 @Test
 public void testAddOrderItem() {
  //第一种加insert="false" update="false"
  orderItem.setProductId(45);
  orderItem.setQuaneity(99);
  order.setOrderId(1);
  orderItem.setOrder(order);
  this.orderDao.addOrderItem(orderItem);
  
  //第二种加insert="false" update="false"
//  orderItem.setOid(1);
//  orderItem.setProductId(54);
//  orderItem.setQuaneity(91);
//  this.orderDao.addOrderItem(orderItem);
 }
}

当 property 没有设置insert和update属性时会报错：

<property name="oid" type="java.lang.Integer" column="oid" ></property>

报错：
Repeated(重复) column in mapping for entity: com.zking.four.entity.OrderItem column: oid (should be mapped with insert=“false” update=“false”)

原因：同一个字段（外键oid在orderItem.hbm.xml中）被映射了两次
解决方案：
1、删除从表对应的实体类中的外键属性（把order里的oid删除）
2、在配置的xml中外键属性上添加 insert=false，update=false的设置。
3、在配置的xml中的manyToOne标签中添加insert=false，update=false的设置。
orderItem.hbm.xml里的字段重复了 oid

在这里插入图片描述

hibernate：普通删除

1.hibernate.cfg.xml,order.hbm.xml,orderItem.hbm.xml与上面相同
2.dao方法：

//普通删除
 public void deleteOrder(Order order) {
  Session session = SessionFactoryUtils.getSession();
  Transaction transaction = session.beginTransaction();
  Order o = session.get(Order.class, order.getOrderId());      //找到数据
  for (OrderItem ot : o.getOrderItems()) {
   session.delete(ot);          //删除订单项
  }
  session.delete(o);      //删除订单
  transaction.commit();
  session.close();
 }

3:junit测试：

@Test
 public void testDeleteOrder() {
  order.setOrderId(3);
  this.orderDao.deleteOrder(order);
 }

Hibernate：级联新增与普通删除

Hibernate：级联新增

hibernate：普通删除

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