hibernate注解配置举例说明

Hibernate Annotation   (Hibernate 注解)

 

进入：http://www.hibernate.org

说明文档：

英文：http://docs.jboss.org/hibernate/annotations/3.5/reference/en/html_single/

中文：http://docs.jboss.org/hibernate/annotations/3.4/reference/zh_cn/html_single/

下载：hibernate annotation 3.4.0 GA

得到：hibernate-annotations.jar

　　　hibernate-commons-annotation.jar

　　　ejb3-persistence.jar

数据库：mysql

category表：id，name，description       <Pk>id

product表：id,name ,price, description ,category_id                  <pk>id  <fk>category_id

新建java project项目：

Add Hibernate Capabilities

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:3307/users
  </property>
  <property name="connection.username">root</property>
  <property name="connection.password">root</property>
  <property name="connection.driver_class">
   com.mysql.jdbc.Driver
  </property>
  <property name="myeclipse.connection.profile">
   mysqlusers
  </property>
  <property name="format_sql">true</property>
  <property name="show_sql">true</property>
  <property name="current_session_context_class">thread</property>
  <mapping class="com.b510.examples.Product" />
  <mapping class="com.b510.examples.Category" />

 </session-factory>

</hibernate-configuration>

利用Hibernate的逆向工程生成：

Category.java      and           Product.java  

Category.java

package com.b510.examples;

import java.util.HashSet;
import java.util.Set;

// 标准注解

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

//增加的注解

import org.hibernate.annotations.GenericGenerator;

//当前的类是一个持久化类，是Category这个类。他映射了一个表category。所对应的 数据库是users
//这句：@Table(name = "category", catalog = "users")  可以省略
@Entity
@Table(name = "category", catalog = "users")

public class Category implements java.io.Serializable {

 private static final long serialVersionUID = 3240281547213597385L;
 private Integer id;
 private String name;
 private String description;
 private Set<Product> products = new HashSet<Product>(0);

 
 public Category() {
 }

 public Category(String name, String description, Set<Product> products) {
  this.name = name;
  this.description = description;
  this.products = products;
 }

 // 主键 ：@Id    主键生成方式：strategy = "increment"
 //映射表中id这个字段，不能为空，并且是唯一的
 @GenericGenerator(name = "generator", strategy = "increment")
 @Id
 @GeneratedValue(generator = "generator")
 @Column(name = "id", unique = true, nullable = false)
 public Integer getId() {
  return this.id;
 }

 public void setId(Integer id) {
  this.id = id;
 }

 //映射表中name这个字段 ，长度是500
 @Column(name = "name", length = 500)
 public String getName() {
  return this.name;
 }

 public void setName(String name) {
  this.name = name;
 }
 
 //映射表中description这个字段 ，长度是500
 @Column(name = "description", length = 500)
 public String getDescription() {
  return this.description;
 }

 public void setDescription(String description) {
  this.description = description;
 }

 //级联操作：cascade = CascadeType.ALL
 //延迟加载：fetch = FetchType.LAZY
 //映射：mappedBy = "category"
 //一对多方式
 @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "category")
 public Set<Product> getProducts() {
  return this.products;
 }

 public void setProducts(Set<Product> products) {
  this.products = products;
 }

}

Product.java

package com.b510.examples;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import org.hibernate.annotations.GenericGenerator;


@Entity
@Table(name = "product", catalog = "users")
public class Product implements java.io.Serializable {

 private static final long serialVersionUID = -1546206493725028472L;
 private Integer id;
 private Category category;
 private String name;
 private String price;
 private String descripton;

 
 public Product() {
 }

 public Product(Category category, String name, String price,
   String descripton) {
  this.category = category;
  this.name = name;
  this.price = price;
  this.descripton = descripton;
 }
 
 @GenericGenerator(name = "generator", strategy = "increment")
 @Id
 @GeneratedValue(generator = "generator")
 @Column(name = "id", unique = true, nullable = false)
 public Integer getId() {
  return this.id;
 }

 public void setId(Integer id) {
  this.id = id;
 }

 //延迟加载：多对一方式
 //关联信息：外键name = "category_id"
 @ManyToOne(fetch = FetchType.LAZY)
 @JoinColumn(name = "category_id")
 public Category getCategory() {
  return this.category;
 }

 public void setCategory(Category category) {
  this.category = category;
 }

 @Column(name = "name", length = 500)
 public String getName() {
  return this.name;
 }

 public void setName(String name) {
  this.name = name;
 }

 @Column(name = "price", length = 10)
 public String getPrice() {
  return this.price;
 }

 public void setPrice(String price) {
  this.price = price;
 }

 @Column(name = "descripton", length = 500)
 public String getDescripton() {
  return this.descripton;
 }

 public void setDescripton(String descripton) {
  this.descripton = descripton;
 }

}

测试代码：

HibernateTest.java

/**
 * 
 */
package com.b510.examples;

import java.util.Set;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.cfg.Configuration;

/**
 *
 * @author XHW
 *
 * @date 2011-7-20
 *
 */
public class HibernateTest {

 public static void main(String[] args) {
  HibernateTest test=new HibernateTest();
  test.add();
  test.find();
 }
 public void add(){
 Configuration config=new AnnotationConfiguration();
 config.configure();
 SessionFactory sessionFactory=config.buildSessionFactory();
 Session session=sessionFactory.getCurrentSession();
 session.beginTransaction();
 Category c=(Category)session.get(Category.class, 5);
 
 Product p=new Product();
 p.setName("计算机科学与技术");
 p.setPrice("123");
 p.setDescripton("计算机科学与技术,好啊，真是红啊");
 
 p.setCategory(c);
 c.getProducts().add(p);
 
 session.save(p);
 session.getTransaction().commit();
 }
 
 
 public void find(){
  Configuration config=new AnnotationConfiguration();
  config.configure();
  SessionFactory sessionFactory=config.buildSessionFactory();
  Session session=sessionFactory.getCurrentSession();
  session.beginTransaction();
  Category c=(Category)session.get(Category.class, 5);
   System.out.println("id: "+c.getId()+"  name:"+c.getName());
   Set<Product> p=c.getProducts();
   for(Product product:p){
    System.out.println("id:"+product.getId()+"  name:"+product.getName()+"  description:"+product.getDescripton());
   }
   session.getTransaction().commit();
 }
}

运行效果：

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.annotations.Version).
log4j:WARN Please initialize the log4j system properly.
Hibernate: 
    select
        category0_.id as id1_0_,
        category0_.description as descript2_1_0_,
        category0_.name as name1_0_ 
    from
        users.category category0_ 
    where
        category0_.id=?
Hibernate: 
    select
        products0_.category_id as category5_1_,
        products0_.id as id1_,
        products0_.id as id0_0_,
        products0_.category_id as category5_0_0_,
        products0_.descripton as descripton0_0_,
        products0_.name as name0_0_,
        products0_.price as price0_0_ 
    from
        users.product products0_ 
    where
        products0_.category_id=?
Hibernate: 
    select
        max(id) 
    from
        product
Hibernate: 
    insert 
    into
        users.product
        (category_id, descripton, name, price, id) 
    values
        (?, ?, ?, ?, ?)
Hibernate: 
    select
        category0_.id as id5_0_,
        category0_.description as descript2_5_0_,
        category0_.name as name5_0_ 
    from
        users.category category0_ 
    where
        category0_.id=?
id: 5  name:xml33
Hibernate: 
    select
        products0_.category_id as category5_1_,
        products0_.id as id1_,
        products0_.id as id4_0_,
        products0_.category_id as category5_4_0_,
        products0_.descripton as descripton4_0_,
        products0_.name as name4_0_,
        products0_.price as price4_0_ 
    from
        users.product products0_ 
    where
        products0_.category_id=?
id:9  name:计算机科学与技术  description:计算机科学与技术,好啊，真是红啊