Hibernate一对多双向关联

一种商品类别下有多个商品，多个商品对应同一个商品类别,这种关系就是一对多双向关联。

商品类：

package com.pojo;
/**
 * Product entity.
 * 
 * @author MyEclipse Persistence Tools
 */
public class Product implements java.io.Serializable {
	private static final long serialVersionUID = -7963752710605063544L;
	private int id;
	private String productname;
	private String remark;
	// 多对一
	private Category category;
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public Category getCategory() {
		return category;
	}
	public void setCategory(Category category) {
		this.category = category;
	}
	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;
	}
}

商品类别：

package com.pojo;
import java.util.HashSet;
import java.util.Set;
/**
 * Category entity.
 * 
 * @author MyEclipse Persistence Tools
 */
public class Category implements java.io.Serializable {
	private static final long serialVersionUID = -666185106951167028L;
	private int id;
	private String name;
	private String mark;
	// 集合，一对多
	private Set<Product> products = new HashSet<Product>();
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public Set<Product> getProducts() {
		return products;
	}
	public void setProducts(Set<Product> products) {
		this.products = products;
	}
	public Category() {
	}
	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;
	}
}

XML配置文件，一对多的关系：

<?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，一种商品类型有多个商品 -->
        <set name="products" cascade="all" outer-join="true">
        <key column="producttypeid" foreign-key="id"></key>
        <one-to-many class="com.pojo.Product" />
        </set>
        
    </class>
</hibernate-mapping>

多个商品对应一个商品类别：

<?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.Product" table="PRODUCT" schema="ZM">
        <id name="id" type="java.lang.Integer">
            <column name="ID" precision="8" scale="0" />
            <generator class="increment" />
        </id>
        <property name="productname" type="java.lang.String">
            <column name="PRODUCTNAME" length="100" />
        </property>
        <property name="remark" type="java.lang.String">
            <column name="REMARK" length="100" />
        </property>
        <!-- 多对一，多个商品对应一个分类 -->
        <many-to-one name="category" class="com.pojo.Category" outer-join="true" >
        <column name="producttypeid"></column>        
        </many-to-one>
    </class>
</hibernate-mapping>

测试类：

package com.test;
import java.util.List;
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.delete();
	}
	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.getProducts();
		set.add(p);
		set.add(p1);
		// 直接保存商品类别，商品自动级联就保存
		session.save(c);
		try {
			HibernateManager.closeSession();
		} catch (Exception e) {
			e.printStackTrace();
			HibernateManager.rollbackTransaction();
		}
	}
	public static void loadPro() {
		Session session = HibernateManager.openSession();
		Product p = (Product) session.load(Product.class, new Integer(1));
		System.out.println("类别编号:" + p.getCategory().getId());
		System.out.println("类别名称:" + p.getCategory().getName());
		System.out.println("类别描述:" + p.getCategory().getMark());
		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();
		}
	}
	@SuppressWarnings("unchecked")
	public static void loadProList() {
		Session session = HibernateManager.openSession();
		// 先获取类型
		List<Product> list = session.createQuery("from Product").list();
		for (Product p : list) {
			System.out.println("类别编号:" + p.getCategory().getId());
			System.out.println("类别名称:" + p.getCategory().getName());
			System.out.println("类别描述:" + p.getCategory().getMark());
			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());
			System.out.println("<br/>");
		}
		try {
			HibernateManager.closeSession();
		} catch (Exception e) {
			e.printStackTrace();
			HibernateManager.rollbackTransaction();
		}
	}
	// 修改商品类型，级联操作
	public static void updateCate() {
		Session session = HibernateManager.openSession();
		Category c = (Category) session.load(Category.class, new Integer(1));
		Set<Product> products = c.getProducts();
		for (Product p : products) {
			if (p.getId() == 1) {
				p.setProductname("诺基亚6300");
				p.setRemark("very good");
			}
		}
		session.update(c);
		try {
			HibernateManager.closeSession();
		} catch (Exception e) {
			e.printStackTrace();
			HibernateManager.rollbackTransaction();
		}
	}
	// 修改商品类型，级联操作
	public static void updatePro() {
		Session session = HibernateManager.openSession();
		Product p = (Product) session.load(Product.class, new Integer(1));
		Category c = p.getCategory();
		p.setProductname("三星");
		p.setRemark("很实用的手机");
		session.update(c);
		try {
			HibernateManager.closeSession();
		} catch (Exception e) {
			e.printStackTrace();
			HibernateManager.rollbackTransaction();
		}
	}
	// 删除某一类别，并级联删除该类别下面的所有商品
	public static void delete() {
		Session session = HibernateManager.openSession();
		Category c = (Category) session.load(Category.class, new Integer(1));
		//级联删除
		session.delete(c);
		try {
			HibernateManager.closeSession();
		} catch (Exception e) {
			e.printStackTrace();
			HibernateManager.rollbackTransaction();
		}
	}
}