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"?> <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> <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