Hibernate Annotation 基于外键的单向多对一关联
其实一对多和多对一是一样的，只是看问题的角度不同。
需要的注解标签请参考前面的文章，那些标签是我从前面项目总结下来的
SQL脚本：
-- MySQL dump 10.13 Distrib 5.1.55, for Win32 (ia32)---- Host: localhost Database: hibernate_demo-- -------------------------------------------------------- Server version5.1.55-community/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;/*!40101 SET NAMES utf8 */;/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;/*!40103 SET TIME_ZONE='+00:00' */;/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;---- Table structure for table `category`--DROP TABLE IF EXISTS `category`;/*!40101 SET @saved_cs_client = @@character_set_client */;/*!40101 SET character_set_client = utf8 */;CREATE TABLE `category` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(30) NOT NULL, `description` varchar(30) NOT NULL, PRIMARY KEY (`id`)) ENGINE=MyISAM AUTO_INCREMENT=2 DEFAULT CHARSET=utf-8;/*!40101 SET character_set_client = @saved_cs_client */;---- Dumping data for table `category`--LOCK TABLES `category` WRITE;/*!40000 ALTER TABLE `category` DISABLE KEYS */;INSERT INTO `category` VALUES (1,'fruit','fruit category');/*!40000 ALTER TABLE `category` ENABLE KEYS */;UNLOCK TABLES;---- Table structure for table `product`--DROP TABLE IF EXISTS `product`;/*!40101 SET @saved_cs_client = @@character_set_client */;/*!40101 SET character_set_client = utf8 */;CREATE TABLE `product` ( `id` int(11) NOT NULL, `name` varchar(30) NOT NULL, `price` int(11) NOT NULL, `description` varchar(30) NOT NULL, `category_id` int(11) NOT NULL, PRIMARY KEY (`id`), KEY `product_fk` (`category_id`)) ENGINE=MyISAM DEFAULT CHARSET=latin1;/*!40101 SET character_set_client = @saved_cs_client */;---- Dumping data for table `product`--LOCK TABLES `product` WRITE;/*!40000 ALTER TABLE `product` DISABLE KEYS */;INSERT INTO `product` VALUES (1,'apple',10,'apple',1);/*!40000 ALTER TABLE `product` ENABLE KEYS */;UNLOCK TABLES;/*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */;/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;-- Dump completed on 2012-08-08 22:34:53?
//Category.java
package com.zyp.examples;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.Table;import org.hibernate.annotations.GenericGenerator;/** * Category entity. @author MyEclipse Persistence Tools */@Entity@Table(name="category")public class Category implements java.io.Serializable {// Fieldsprivate static final long serialVersionUID = 3763960444574701564L;@Id@GenericGenerator(name="incrementGenerator", strategy="increment")@GeneratedValue(generator="incrementGenerator", strategy=GenerationType.IDENTITY)@Column(name="id")private Integer id;@Column(name="name",nullable=false, insertable=true)private String name;@Column(name="description", nullable=false, insertable=true)private String description;// Constructors/** default constructor */public Category() {}/** full constructor */public Category(String name, String description) {this.name = name;this.description = description;}// Property accessorspublic Integer getId() {return this.id;}public void setId(Integer id) {this.id = id;}public String getName() {return this.name;}public void setName(String name) {this.name = name;}public String getDescription() {return this.description;}public void setDescription(String description) {this.description = description;}}?//Product.java
package com.zyp.examples;import javax.persistence.CascadeType;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.FetchType;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.ManyToOne;import javax.persistence.Table;import org.hibernate.annotations.GenericGenerator;/** * Product entity. @author MyEclipse Persistence Tools */@Entity@Table(name="product")public class Product implements java.io.Serializable {// Fieldsprivate static final long serialVersionUID = -485648626582047874L;@Id@GenericGenerator(name="incrementGenerator", strategy="increment")@GeneratedValue(generator="incrementGenerator", strategy=GenerationType.IDENTITY)@Column(name="id")private Integer id;@Column(name="name")private String name;@Column(name="price")private Integer price;@Column(name="description")private String description;@ManyToOne(targetEntity=Category.class, fetch=FetchType.LAZY, cascade={CascadeType.ALL})@JoinColumn(name="category_id")private Category category;// Constructors/** default constructor */public Product() {}// Property accessorspublic Integer getId() {return this.id;}public void setId(Integer id) {this.id = id;}public String getName() {return this.name;}public void setName(String name) {this.name = name;}public Integer getPrice() {return this.price;}public void setPrice(Integer price) {this.price = price;}public String getDescription() {return this.description;}public void setDescription(String description) {this.description = description;}public Category getCategory() {return category;}public void setCategory(Category category) {this.category = category;}}?//HibernateUti.java
package com.zyp.examples;import org.hibernate.SessionFactory;import org.hibernate.cfg.AnnotationConfiguration;import org.hibernate.cfg.Configuration;public class HibernateUtil {private static SessionFactory sessionFactory;static {try {sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();} catch (Throwable ex) {throw new ExceptionInInitializerError(ex);}}public static SessionFactory getSessionFactory() {return sessionFactory;}public static void shutdown() {getSessionFactory().close();}}?//Hibernate.cfg.xml
<?xml version='1.0' encoding='UTF-8'?><!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"><!-- Generated by MyEclipse Hibernate Tools. --><hibernate-configuration><session-factory><property name="dialect">org.hibernate.dialect.MySQLDialect</property><property name="connection.url">jdbc:mysql://localhost:3306/hibernate_demo</property><property name="connection.username">root</property><property name="connection.password">123</property><property name="connection.driver_class">com.mysql.jdbc.Driver</property><property name="myeclipse.connection.profile">mysql</property><property name="show_sql">true</property><property name="format_sql">true</property><mapping /><mapping /></session-factory></hibernate-configuration>?
经过这个例子，我也发现主键生成方式参数的设定了，呵呵。。
@Id@GenericGenerator(name="incrementGenerator(可以随便取一个名字)", strategy="increment(主键生成策略)")@GeneratedValue(generator="incrementGenerator(和上面的保持一致)", strategy=GenerationType.IDENTITY(根据需要从注解中选一个值))@Column(name="id")private Integer id;