Hibernate级联操作

//订单-----多的一方public class Order {private Integer id;private Double money;private String receiverInfo; // 收货地址// 订单与客户关联private Customer c; // 描述订单属于某一个客户public Customer getC() {return c;}public void setC(Customer c) {this.c = c;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public Double getMoney() {return money;}public void setMoney(Double money) {this.money = money;}public String getReceiverInfo() {return receiverInfo;}public void setReceiverInfo(String receiverInfo) {this.receiverInfo = receiverInfo;}}

//客户 ------一的一方public class Customer {private Integer id; // 主键private String name; // 姓名// 描述客户可以有多个订单private Set<Order> orders = new HashSet<Order>();public Set<Order> getOrders() {return orders;}public void setOrders(Set<Order> orders) {this.orders = orders;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}}

<?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> ???<!-- name表示类的全路径 ???catalog表示数据库名 ?默认为cfg配置文件的数据库名 ??table需要创建的表名 --> ???<class name="com.baidu.test.Order" catalog="test" table="o_order"> <!-- private Integer id;private Double money;private String receiverInfo; // 收货地址 private Customer c; // 描述订单属于某一个客户--><!-- name表示po类中的对应主键字段 ???column表示数据库表里面的字段 --> ???<id name="id" column="o_id"> ???<generator class="identity"></generator> ???</id> ???<property name="money" column="o_money"></property> ???<property name="receiverInfo" length="100" column="o_receiverInfo"></property> ???<!-- 多对一 ????多个订单属于一个用户的 ???class表示类的全路径 ?--> ???<many-to-one name="c" class="com.baidu.test.Customer" column="o_customer_id" ></many-to-one> ???</class> ???</hibernate-mapping>

<?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 name="com.baidu.test.Customer" catalog="test" table="c_customer"><!-- private Integer id; // 主键private String name; // 姓名// 描述客户可以有多个订单private Set<Order> orders = new HashSet<Order>(); --> ???<id name="id" column="c_id"> ???<generator class="identity"></generator> ???</id> ???<property name="name" length="30"></property> ???<!-- 用来描述多在一的一方关联多的一方 ?name ?表示订单变量 --> ???<set name="orders" cascade="save-update"> ???<!-- key 用来描述多的一方产生的外键名称 --> ???<key column="o_customer_id"></key> ???<!-- 关联的类 --> ???<one-to-many class="com.baidu.test.Order"/> ???</set> ???</class> ???</hibernate-mapping>

 ??　　 @Testpublic void test01(){//获取连接Session session = HibernateUtils.getSession();//开启事务Transaction ts = session.beginTransaction();//处于游离态 ?没有oid ?与session无关 Order o=new Order();o.setMoney(123.0);o.setReceiverInfo("123333");HashSet<Order> hashSet = new HashSet<Order>(); hashSet.add(o);Customer c=new Customer();c.setName("123556");c.setOrders(hashSet);session.save(o);//处于持久态 ?与session有关 ?有oidsession.save(c);ts.commit();session.close();} ???

　　　　@Test//测试单项级联public void test02(){Session session = HibernateUtils.getSession();Transaction bt = session.beginTransaction();//操作Order o=new Order();o.setMoney(123.0);o.setReceiverInfo("123333");HashSet<Order> hashSet = new HashSet<Order>(); hashSet.add(o);Customer c=new Customer();c.setName("123556");c.setOrders(hashSet);session.save(c);//处于持久态 ?与session有关 ?有oidbt.commit();session.close();}

我们在开发中要配置双向关联配置。---------可以通过任意一方来操作对方在操作代码，尽量来要进行单向关联。------可以尽量资源浪费。在双向关联中，会存在多余的update语句。我们可以使用inverse属性来设置，双向关联时由哪一方来维护表与表之间的关系。Inverse它的值如果为true代表，由对方来维护外键。Inverse它的值如果为false代表，由本方来维护外键。关于inverse的取值:外键在哪一个表中，我们就让哪一方来维护外键。

package com.baidu.test1;import javax.persistence.CascadeType;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.ManyToOne;import javax.persistence.Table;//订单-----多的一方@Entity@Table(name="t_order")public class Order {/*@Id@GenericGenerator(name="myuuid",strategy="uuid")@GeneratedValue(generator="myuuid")*/@Id@GeneratedValue(strategy=GenerationType.IDENTITY)private Integer id;@Column(name="t_money")private Double money;private String receiverInfo; // 收货地址// 订单与客户关联@ManyToOne(targetEntity=Customer.class)@JoinColumn(name="c_customer_id")//添加外键private Customer c; // 描述订单属于某一个客户public Customer getC() {return c;}public void setC(Customer c) {this.c = c;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public Double getMoney() {return money;}public void setMoney(Double money) {this.money = money;}public String getReceiverInfo() {return receiverInfo;}public void setReceiverInfo(String receiverInfo) {this.receiverInfo = receiverInfo;}}

package com.baidu.test1;import java.util.HashSet;import java.util.Set;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.OneToMany;import javax.persistence.Table;import org.hibernate.annotations.Cascade;import org.hibernate.annotations.CascadeType;//客户 ------一的一方@Entity//表示po类 ?声明一个实类@Table(name="t_customer")public class Customer {@Id@GeneratedValue(strategy=GenerationType.IDENTITY)//设置主键的模式为自增长private Integer id; // 主键@Column(name="t_name",length=50)private String name; // 姓名//mappedBy相当于inverse="true"// 描述客户可以有多个订单 ?表示一对多@OneToMany(targetEntity=Order.class,mappedBy="c",cascade=javax.persistence.CascadeType.ALL)//@Cascade(CascadeType.SAVE_UPDATE)private Set<Order> orders = new HashSet<Order>();public Set<Order> getOrders() {return orders;}public void setOrders(Set<Order> orders) {this.orders = orders;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}}

 ????<mapping class="com.baidu.test1.Order"/> ????<mapping class="com.baidu.test1.Customer"/> ???????

@Test//测试单项级联public void test02(){Session session = HibernateUtils.getSession();Transaction bt = session.beginTransaction();//操作Order o=new Order();o.setMoney(123.0);o.setReceiverInfo("123333");HashSet<Order> hashSet = new HashSet<Order>(); hashSet.add(o);Customer c=new Customer();c.setName("123556");c.setOrders(hashSet);o.setC(c); ?//使用注解开发 ??必须在这里添加映射关系 ?否则会在customer中的外键不会产生之值session.save(c);//处于持久态 ?与session有关 ?有oidbt.commit();session.close();}