剛才看了下<精通hibernate>,感覺關于映射關系,尤其是一對多,多對一,多對多關系應該是核心的東西,記錄下.
業務邏輯:一個客戶(Customer)對應多個訂單(Order)
方式一: 雙向一對多
PO:
Customer:
package net.foxlog.prj.business;
import java.io.Serializable;
import java.util.Set;
import org.apache.commons.lang.builder.ToStringBuilder;
/** @author Hibernate CodeGenerator */
public class Customer implements Serializable {
/** identifier field */
private Long id;
/** nullable persistent field */
private String name;
/** persistent field */
private Set orders;
/** full constructor */
public Customer(String name, Set orders) {
this.name = name;
this.orders = orders;
}
/** default constructor */
public Customer() {
}
/** minimal constructor */
public Customer(Set orders) {
this.orders = orders;
}
public Long getId() {
return this.id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
public Set getOrders() {
return this.orders;
}
public void setOrders(Set orders) {
this.orders = orders;
}
public String toString() {
return new ToStringBuilder(this)
.append("id", getId())
.toString();
}
}Order:
package net.foxlog.prj.business;
import java.io.Serializable;
import org.apache.commons.lang.builder.ToStringBuilder;
/** @author Hibernate CodeGenerator */
public class Order implements Serializable {
/** identifier field */
private Long id;
/** nullable persistent field */
private String orderNumber;
/** nullable persistent field */
private Customer customer;
/** full constructor */
public Order(String orderNumber, Customer customer) {
this.orderNumber = orderNumber;
this.customer = customer;
}
/** default constructor */
public Order() {
}
public Long getId() {
return this.id;
}
public void setId(Long id) {
this.id = id;
}
public String getOrderNumber() {
return this.orderNumber;
}
public void setOrderNumber(String orderNumber) {
this.orderNumber = orderNumber;
}
public Customer getCustomer() {
return this.customer;
}
public void setCustomer(Customer customer) {
this.customer = customer;
}
public String toString() {
return new ToStringBuilder(this)
.append("id", getId())
.toString();
}
}
配置文件
Customer.hbm.xml:
xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping
PUBLIC "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping >
<class name="net.foxlog.prj.business.Customer" table="CUSTOMERS" >
<id name="id" type="long" column="ID">
<generator class="increment"/>
</id>
<property name="name" type="string" >
<column name="NAME" length="15" />
</property>
<set
name="orders"
cascade="all-delete-orphan"
inverse="true"
>
<key column="CUSTOMER_ID" />
<one-to-many class="net.foxlog.prj.business.Order" />
</set>
<!--
<set
name="orders"
inverse="true"
cascade="save-update"
>
<key column="CUSTOMER_ID" />
<one-to-many class="mypack.Order" />
</set>
-->
</class>
</hibernate-mapping> Order.hbm.xml:
xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping
PUBLIC "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping >
<class name="net.foxlog.prj.business.Order" table="ORDERS">
<id name="id" type="long" column="ID">
<generator class="increment"/>
</id>
<property name="orderNumber" type="string" >
<column name="ORDER_NUMBER" length="15" />
</property>
<many-to-one
name="customer"
column="CUSTOMER_ID"
class="net.foxlog.prj.business.Customer"
cascade="save-update"
/>
</class>
</hibernate-mapping> 測試類 CustomerTest.java
package net.foxlog.prj.business;
import net.sf.hibernate.Session;
import net.foxlog.prj.dao.DBUtil;
import net.sf.hibernate.Transaction;
import java.util.HashSet;
public class CustomerTest {
public CustomerTest() {
}
public static void test(){
try{
new CustomerTest().saveCustomerAndOrderWithCascade();
}catch(Exception ex){
ex.printStackTrace();
}
}
//保存級聯信息 客戶-訂單
public void saveCustomerAndOrderWithCascade() throws Exception{
Session session = DBUtil.currentSession();
Transaction tx = null;
try{
tx = session.beginTransaction();
Customer custmer = new Customer("Jack",new HashSet());
Order order = new Order();
order.setCustomer(custmer);
order.setOrderNumber("JackOrder001");
custmer.getOrders().add(order);
session.save(custmer);
tx.commit();
}catch(Exception ex){
}
}
}
方式二: 單項多對一
即在Cutomer中沒有Order的信息(PO和xml文件),在Order中設置Customer信息(同上)
保存客戶和訂單信息代碼如下:
tx = session.beginTransaction();
Customer customer=new Customer("Jack");
Order order1=new Order("Jack_Order001",customer);
Order order2=new Order("Jack_Order002",customer);
session.save(order1);
session.save(order2);
tx.commit();
方法二很少用,不過有時我倒是喜歡用它,因為存儲完全由自己的業務邏輯控制,也是比較方便的,以前的一個項目就是這么用,表之間的關系基本沒有,相關聯的信息完全自己當作一個個獨立的表進行插入