Hibernate 第一个示例说明

下文是笔者编写的第一个Hibernate示例，如下所示:
 
第一步:持久化类
第二步:创建table
第三步:编写相应的映射文件
第四步：编写相应的Java操作文件，如下例所示:
 

持久化类

 public class User {
   private int id;
   private String name;   
   private int salary;  

   public User () {
      name=null; 
      salary =0;
   }
   public User (String name, int salary) {
      this.name = name; 
      this.salary = salary;
   }
   public int getId() {
      return id;
   }
   public void setId( int id ) {
      this.id = id;
   }
   public String getname() {
      return name;
   }
   public void setname( String name ) {
      this.name = name; 
 }
   public int getSalary() {
      return salary;
   }
   public void setSalary( int salary ) {
      this.salary = salary;
   }
}

数据表信息

create table tbUser (
    id INT NOT NULL auto_increment,
     name nVARCHAR(20) default NULL 
    salary     INT  default NULL,
    PRIMARY KEY (id)
);

映射文件

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
 "-//Hibernate/Hibernate Mapping DTD//EN"
 "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> 

<hibernate-mapping>
   <class name="User" table="tbUser">
      <meta attribute="class-description">
         This class contains the User detail. 
      </meta>
      <id name="id" type="int" column="id">
         <generator class="native"/>
      </id>
      <property name="name" column=" name" type="string"/> 
      <property name="salary" column="salary" type="int"/>
   </class>
</hibernate-mapping>

映射文件注意事项:
  1.映射文件需使用 <classname>.hbm.xml 文件名保存 ，如: user.hbm.xml
  2.标签说明:
      class标签用于 其中的name属性表示 Java类名称，table属性值表示数据库表名称
      meta标签是一个可选元素，用于修饰类
      id标签通常用于表示主键
         generator标签:可以设置 native 使 Hibernate 可以使用 identity, sequence 或 hilo 算法根据底层数据库的情况来创建主键
      property标签用于表示Java中类的属性同数据库列的匹配关系
          name属性值：用于设置类的属性名
          column:用于定义数据库中表的列名称
          type:用于定义数据库表中的列名称 

编写应用程序类信息

import java.util.list; 
import java.util.Date;
import java.util.Iterator; 

import org.hibernate.HibernateException; 
import org.hibernate.Session; 
import org.hibernate.Transaction;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class ManageUser{
   private static SessionFactory factory; 
   public static void main(String[] args) {
      try{
         factory = new Configuration().configure().buildSessionFactory();
      }catch (Throwable ex) { 
         System.err.println("Failed to create sessionFactory object." + ex);
         throw new ExceptionInInitializerError(ex); 
      }
       ManageUser m = new ManageUser();

 
      Integer u1= m.addUser("zhangSan", 88);
      Integer u2= m.addUser("liSi",99);
      Integer u3= m.addUser("wangEr",100);

     
      m.listUser();

      /* Update user records */
      m.updateUser(u1, 888888);
 
      m.deleteUser(u2);
 
      m.listUser();
   } 
   public Integer addUser(String name,   int salary){
      Session session = factory.openSession();
      Transaction tx = null;
      Integer id= null;
      try{
         tx = session.beginTransaction();
         User user= new User(name,salary);
         id= (Integer) session.save(user); 
         tx.commit();
      }catch (HibernateException e) {
         if (tx!=null) tx.rollback();
         e.printStackTrace(); 
      }finally {
         session.close(); 
      }
      return id;
   }
   
   public void listUser( ){
      Session session = factory.openSession();
      Transaction tx = null;
      try{
         tx = session.beginTransaction();
         List users= session.createQuery("FROM User").list(); 
         for (Iterator iterator = 
                           users.iterator(); iterator.hasNext();){
            User user= (User) iterator.next(); 
            System.out.print("Name: " + user.getName()); 
            System.out.println("  Salary: " + user.getSalary()); 
         }
         tx.commit();
      }catch (HibernateException e) {
         if (tx!=null) tx.rollback();
         e.printStackTrace(); 
      }finally {
         session.close(); 
      }
   }
   
   public void updateUser(Integer id, int salary ){
      Session session = factory.openSession();
      Transaction tx = null;
      try{
         tx = session.beginTransaction();
         User user= 
                    (User)session.get(User.class, id); 
         user.setSalary( salary );
         session.update(user); 
         tx.commit();
      }catch (HibernateException e) {
         if (tx!=null) tx.rollback();
         e.printStackTrace(); 
      }finally {
         session.close(); 
      }
   }
 
   public void deleteUser(Integer id){
      Session session = factory.openSession();
      Transaction tx = null;
      try{
         tx = session.beginTransaction();
         User user = 
                   (User)session.get(User.class, id); 
         session.delete(user); 
         tx.commit();
      }catch (HibernateException e) {
         if (tx!=null) tx.rollback();
         e.printStackTrace(); 
      }finally {
         session.close(); 
      }
   }
}