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