Eclipse下Hibernate入门

Eclipse下Hibernate入门

最近boss让做项目，借机学习了一下Hibernate，小有收获。
     hiberante是对数据库持久层访问的一种机制，hibernate的应用可以使程序员将重点放到业务逻辑的实现上。hibernate的原理是将数据库结构封装，使程序员可以像使用普通对象一样调用数据库的相关接口，从实现数据库的相关操作。

     由于Exadel基于eclipse集成了Hibernate，并且方便易用所以我选用
     Exadel+Mysql
     还需要hibernate3.jar http://www.hibernate.org
             mysql-connector http://dev.mysql.com/downloads/

       在Mysql中新建test数据库（Mysql其实有个空的test数据库），然后新建下面的Table

create table user (
id int(10) not null auto_increment primary key,
name varchar(20) not null,
password varchar(20) not null,
email varchar(50),
address varchar(100)
)type=innodb;

新建Java Project，将Mysql_Driver,Hibernate两个user library添加到该工程的java build path中。

新建与数据表对应的POJO类：User和Contact

/**
*
*
*/
package com.user;

/**
* @author lzy
*
*/
public class User{
    private Integer id;
    private String name;
    private String password;
    private Contact contact;

/**
  * @return Returns the id.
  */
public Integer getId() {
  return id;
}
/**
  * @param id The id to set.
  */
public void setId(Integer id) {
  this.id = id;
}
/**
  * @return Returns the name.
  */
public String getName() {
  return name;
}
/**
  * @param name The name to set.
  */
public void setName(String name) {
  this.name = name;
}
/**
  * @return Returns the password.
  */
public String getPassword() {
  return password;
}
/**
  * @param password The password to set.
  */
public void setPassword(String password) {
  this.password = password;
}
/**
  * @return Returns the contact.
  */
public Contact getContact() {
  return contact;
}
/**
  * @param contact The contact to set.
  */
public void setContact(Contact contact) {
  this.contact = contact;
}


}
/**
*
*/
package com.user;

/**
* @author lzy
*
*/
public class Contact {
private String email;
private String address;

/**
  * @return Returns the address.
  */
public String getAddress() {
  return address;
}
/**
  * @param address The address to set.
  */
public void setAddress(String address) {
  this.address = address;
}
/**
  * @return Returns the email.
  */
public String getEmail() {
  return email;
}
/**
  * @param email The email to set.
  */
public void setEmail(String email) {
  this.email = email;
}
}

添加Hibernate支持，这时系统会要求输入一些信息，按提示即可
完成后系统自动生成hibernate.cfg.xml，User.hbm.xml
映射文件必须稍作修改。

hibernate.cfg.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration
PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN"
"‘ target=_blank>http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
<session-factory >

<property name="hibernate.connection.url">jdbc:mysql://localhost/test</property>
  <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
  <property name="hibernate.connection.username"></property>
  <property name="hibernate.connection.password"></property>

<property name="dialect">org.hibernate.dialect.MySQLDialect</property>

        <property name="hibernate.show_sql">True</property>
        <property name="hibernate.transaction.factory_class">org.hibernate.transaction.JDBCTransactionFactory</property>
     <mapping resource="User.hbm.xml"/>

</session-factory>
</hibernate-configuration>

User.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >

<hibernate-mapping package="com.user">
<class
  name="User"
  table="user"
>
  <id
   name="Id"
   type="integer"
   column="id"
  >
   <generator class="native"/>
  </id>

</class>
</hibernate-mapping>

3.测试
添加一个测试类：HibernateTest

package com.user;

import java.util.List;
import java.util.ListIterator;

import org.hibernate.*;
import org.hibernate.cfg.*;

public class HibernateTest {
    public static void main(String[] args) throws HibernateException {
        SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();

        //
        //testInsert(sessionFactory);

        //
        testQuery(sessionFactory);


        sessionFactory.close();

    }
    public static void testInsert( SessionFactory sessionFactory )throws HibernateException {

      Session session = sessionFactory.openSession();
        Transaction tx= session.beginTransaction();
        User user = new User();
        Contact contact=new Contact();
        contact.setEmail("email");
        contact.setAddress("address");

        user.setName("caterpillar");
        user.setPassword("password");
        user.setContact(contact);

        session.save(user);
        tx.commit();
        session.close();
        System.out.println("OK！");
   }

    public static void testQuery( SessionFactory sessionFactory )throws HibernateException {

     Session session = sessionFactory.openSession();
        Transaction tx= session.beginTransaction();
        User user = new User();
        Contact contact=new Contact();

        Query query=session.createQuery("from User as user");
        //query.setCharacter(1, ‘M‘);
        List names =query.list();
        for(ListIterator it=names.listIterator();it.hasNext();){
           user= (User)it.next();
           System.out.println("Id: " + user.getId());
            System.out.println("name: " + user.getName());
            System.out.println("password: " + user.getPassword());
            if(user.getContact()!=null){

             if(user.getContact().getEmail()!=null){
              System.out.println("Email: " + user.getContact().getEmail());
             }
             if(user.getContact().getAddress()!=null){
              System.out.println("Address: " + user.getContact().getAddress());

             }
            }



        }


        tx.commit();
        session.close();

    }
}

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