Hibernate一对多的单向关联

一个商品类别下对应着多个商品，在关联关系里，就是以集合的方式关联，一般是Set集合

package com.pojo;
import java.util.HashSet;
import java.util.Set;
/**
 * 
 * 商品类别
 */
public class Category implements java.io.Serializable {
	private static final long serialVersionUID = 4772491895582904188L;
	private int id;
	private String name;
	private String mark;
    private Set<Product> product = new HashSet<Product>() ;  //一个商品类别有多个商品，存放在set里面
	
	public Category() {
	}
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return this.name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getMark() {
		return this.mark;
	}
	public void setMark(String mark) {
		this.mark = mark;
	}
	public Set<Product> getProduct() {
		return product;
	}
	public void setProduct(Set<Product> product) {
		this.product = product;
	}
}

package com.pojo;
/**
 * 
 * 
 * 商品
 */
public class Product implements java.io.Serializable {
	private static final long serialVersionUID = -4090151482387518292L;
	private int id;
	private String productname;
	private String remark;
	public Product() {
	}
	public String getProductname() {
		return this.productname;
	}
	public void setProductname(String productname) {
		this.productname = productname;
	}
	public String getRemark() {
		return this.remark;
	}
	public void setRemark(String remark) {
		this.remark = remark;
	}
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
}

在XML文件里面就是配置一对多的关联了：

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
    <class name="com.pojo.Category" table="CATEGORY" schema="ZM">
        <id name="id" type="java.lang.Integer">
            <column name="ID" precision="8" scale="0" />
            <generator class="increment" />
        </id>
        <property name="name" type="java.lang.String">
            <column name="NAME" length="100" />
        </property>
        <property name="mark" type="java.lang.String">
            <column name="MARK" length="100" />
        </property>
        
        <!-- 一对多关联，一种类别对应多个商品  -->
        <set name="product"  >
        <key column="PRODUCTTYPEID" foreign-key="id"></key>
        <one-to-many class="com.pojo.Product" />
        </set>
        
        
    </class>
</hibernate-mapping>

测试类：

package com.test;
import java.util.Set;
import org.hibernate.Session;
import com.pojo.Category;
import com.pojo.Product;
import com.util.HibernateManager;
public class Test1 {
	/**
	 * beckham Dec 14, 2009 7:30:06 PM
	 */
	public static void main(String[] args) {
		Test1.loadPro() ;
	}
	public static void addType() {
		Session session = HibernateManager.openSession();
		Category c = new Category();
		c.setName("电脑");
		c.setMark("这是电脑类别");
		try {
			session.save(c);
			HibernateManager.closeSession();
		} catch (Exception e) {
			e.printStackTrace();
			HibernateManager.rollbackTransaction();
		}
	}
	public static void addPro() {
		Session session = HibernateManager.openSession();
		//获取类型
		Category c = (Category) session.load(Category.class, new Integer(1));
		//商品1
		Product p = new Product();
		p.setProductname("摩托罗拉v8");
		p.setRemark("很好的手机");
		//商品2
		Product p1 = new Product();
		p1.setProductname("摩托罗拉A1200");
		p1.setRemark("非常好的手机");
		
		//一对多关联
		Set<Product> set = c.getProduct() ;
		set.add(p) ;
		set.add(p1) ;
		
		session.save(p) ;
		session.save(p1) ;
		try {
			session.save(p);
			HibernateManager.closeSession();
		} catch (Exception e) {
			e.printStackTrace();
			HibernateManager.rollbackTransaction();
		}
	}
	
	public static void loadPro() {
		Session session = HibernateManager.openSession();
		//先获取类型
		Category c = (Category) session.load(Category.class, new Integer(1));
		System.out.println("类别编号:"+c.getId());
		System.out.println("类别名称:"+c.getName());
		System.out.println("类别描述:"+c.getMark());
		
		//获取该类型下的所有商品
		Set<Product> ps = c.getProduct() ;
		for(Product p:ps){
			System.out.println("商品编号"+p.getId());
			System.out.println("商品名称:"+p.getProductname());
			System.out.println("商品描述："+p.getRemark());
		}
		try {
			HibernateManager.closeSession();
		} catch (Exception e) {
			e.printStackTrace();
			HibernateManager.rollbackTransaction();
		}
	}
}

测试结果：

类别编号:1
Hibernate:
select
category0_.ID as ID1_0_,
category0_.NAME as NAME1_0_,
category0_.MARK as MARK1_0_
from
ZM.CATEGORY category0_
where
category0_.ID=?
类别名称:电脑
类别描述:这是电脑类别
Hibernate:
select
product0_.PRODUCTTYPEID as PRODUCTT4_1_,
product0_.ID as ID1_,
product0_.ID as ID0_0_,
product0_.PRODUCTNAME as PRODUCTN2_0_0_,
product0_.REMARK as REMARK0_0_
from
ZM.PRODUCT product0_
where
product0_.PRODUCTTYPEID=?
商品编号3
商品名称:摩托罗拉A1200
商品描述：非常好的手机
商品编号2
商品名称:摩托罗拉v8
商品描述：很好的手机