Hibernate5配置与使用具体解释

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引言

Hibernate是一个轻量级的持久层开源框架，它是连接java应用程序和关系数据库的中间件，负责java对象和关于Hibernate内部对JDBC API进行封装，负责java对象的持久化。由于他封装了所有的数据訪问细节，使的业务逻辑层开发专注于实现，它是一种优秀的ORM映射工具，提供了完好的对象–关系映射服务。开发过程不依赖容器。灵活性非常大，开源无缝集成到不论什么一个java系统中。

Hibernate5配置

版本号

这里是下载地址：http://hibernate.org/orm/
涉及到訪问数据库还须要数据库驱动器相关的jar包：

搭建使用hibernate的开发环境

你能够创建一个Java project或者一个web project。以上的方式创建的项目均可測试hibernate环境。
本次以创建一个web工程的方式演示搭建开发环境的具体步骤。

1）创建一个web项目。

2）将相关hibernate的包和数据库驱动器的包导入到例如以下图路径：

注意：hibernate的jar包，选择例如以下指定路径下的所有jar将其导入。

3）（在线安装eclipse的插件：hibernate tools。方便编辑”.cfg.xml”和“hbm.xml”格式的文件。安装方法若不熟可自行Google或百度，非本文重点。不再细说。

）
在src目录创建hibernate.cfg.xml文件：

<?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"> <hibernate-configuration> ???<session-factory> ???????<property name="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property> ???????<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> ???????<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hb</property> ???????<property name="hibernate.connection.username">root</property> ???????<property name="hibernate.connection.password">root</property> ???????<property name="hibernate.hbm2ddl.auto">update</property> ???????<mapping resource="com/example/domain/User.hbm.xml"/> ???</session-factory></hibernate-configuration>

上面这个配置文件主要是数据库连接的相关配置，仅仅要配置成你自己的数据库设置就可以。

对于这个maping属性：

<mapping resource="com/example/domain/User.hbm.xml"/>

在你创建完以下的步骤 4和5后，就能够补上，假设有多个javabean类及相应的 **.hbm.xml文件。就须要加入多个这种maping属性。

4）创建你的项目中的javabean类，如User.java

public class User implements Serializable{ ???/** ????* ?????*/ ???private static final long serialVersionUID = 2015771159L;// ?@Id// ?@Basic(fetch=FetchType.EAGER)// ?@GeneratedValue(strategy=GenerationType.AUTO) ???private Long id;// ?@Basic(fetch=FetchType.LAZY)// ?@Column(length=50) ???private String emailName;// ?@Basic(fetch=FetchType.LAZY)// ?@Column(length=50) ???private String emailPassword; ???public User() { ???????// TODO Auto-generated constructor stub ???} ???public Long getId() { ???????return id; ???} ???public void setId(Long id) { ???????this.id = id; ???} ???public String getEmailName() { ???????return emailName; ???} ???public void setEmailName(String emailName) { ???????this.emailName = emailName; ???} ???public String getEmailPassword() { ???????return emailPassword; ???} ???public void setEmailPassword(String emailPassword) { ???????this.emailPassword = emailPassword; ???} ???@Override ???public int hashCode() { ???????return id != null ?
 id.hashCode() : 0; ???} ???@Override ???public boolean equals(Object o) { ???????if ( this == o ) { ???????????return true; ???????} ???????if ( !( o instanceof User ) ) { ???????????return false; ???????} ???????if ( id == null ) { ???????????return false; ???????} ???????return id.equals( ((User) o).id ); ???} ???@Override ???public String toString() { ???????// TODO Auto-generated method stub ???????return super.toString()+"[id="+id+"EmailName="+emailName+"EmailPassword="+emailPassword+"]"; ???}

5）编写数据库表及字段到javabean类User的映射文件。

这个样例中必须创建为文件名称：User.hbm.xml，能够放User类所在包中。

<?xml version="1.0"?
><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" ??????????????????????????????????"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><!-- Generated 2016-7-8 1:31:59 by Hibernate Tools 3.4.0.CR1 --><hibernate-mapping> <class name="com.example.domain.User" table="USER"> ?<id name="id" type="java.lang.Long"> ??<column name="ID" not-null="true"/> ??<generator class="increment"/> ?</id> ?<property generated="never" lazy="false" name="emailName" type="java.lang.String"> ??<column length="50" name="EMAILNAME" not-null="false"/> ?</property> ?<property generated="never" lazy="false" name="emailPassword" type="java.lang.String"> ??<column name="EMAILPASSWORD"/> ?</property> </class></hibernate-mapping>

Hibernate5的使用

接着上述的几节内容。我来说说做关键部分，hibernate的使用。

这一部分我建议看看hibernate的官方文档。毕竟网上的样例各种hibernate版本号的样例都有。不同版本号提供的接口不同，用法也有非常多差别，并且最新的hibernate版本号的使用demo非常难找到。

基本使用思路

**在使用Hibernate运行持久化操作前。须要得到一个Session对象。有了Session对象，就能够以面向对象的方式保存、获取、更新和删除对象。
Session对象能够通过SessionFactory（会话工厂类）的openSession方法来获得。

因此还须要获取SessionFactory对象**，它通过例如以下方式获得：

final StandardServiceRegistry registry = new StandardServiceRegistryBuilder() ?????????????.configure() // 默认使用src目录下的hibernate.cfg.xml进行配置，若更改了路径，要附加上包路径如："/com/example/hibernate.cfg.xml" ????????????.build(); ?????try { ?????????sessionFactory = new MetadataSources( registry ).buildMetadata().buildSessionFactory(); ?????} ?????catch (Exception e) { ?????????StandardServiceRegistryBuilder.destroy( registry ); ?????} 

或者通过例如以下方式获得：

Configuration configuration = new Configuration();// 默认使用src目录下的hibernate.cfg.xml进行配置，若更改了路径。要附加上包路径如："/com/example/hibernate.cfg.xml" ????????SessionFactory sf = configuration.configure().buildSessionFactory(); ???????Session session = sf.openSession();

使用Junit測试搭建的hibernate开发环境

注意測试function中示范了hibernate的用法，这能够用在实际的开发项目中。
Userdao.java的完整源代码：

public class UserDao { ???public UserDao() { ???????// TODO Auto-generated constructor stub ???} ???public static SessionFactory getSessionFactoryInstance(){ ???????if (sessionFactory==null) { ???????????synchronized (SessionFactory.class) { ???????????????if (sessionFactory==null){ ???????????????????config=new Configuration().configure("me/seekout/wanlizhuizong/hibernate.cfg.xml");//若不指定。默认在目录src下 ???????????????????//使用默认配合文件。hibernate.cfg.xml ???????????????????return config.buildSessionFactory(); ???????????????????//另外一种写法。// ?????????????????StandardServiceRegistry standardServiceRegistry=new StandardServiceRegistryBuilder().configure("me/seekout/wanlizhuizong/hibernate.cfg.xml").build();// ?????????????????Metadata metadata = new MetadataSources( standardServiceRegistry ).getMetadataBuilder().applyImplicitNamingStrategy(ImplicitNamingStrategyJpaCompliantImpl.INSTANCE).build();// ?????????????????return metadata.getSessionFactoryBuilder().build(); ???????????????} ???????????} ???????} ???????return sessionFactory; ???} ???/** ????* @param id ????* @return ????* @throws Exception ????*/ ???public User queryById(long id) throws Exception { ???????SessionFactory sessionFactory = HibernateConfigContext ???????????????.getSessionFactoryInstance(); ???????Session session = sessionFactory.openSession(); ???????Transaction transaction = null; ???????User user = null; ???????try { ???????????transaction = session.beginTransaction(); ???????????user = (User) session.get(User.class, id); ???????????transaction.commit(); ???????} catch (Exception e) { ???????????// TODO: handle exception ???????????if (transaction != null) { ???????????????transaction.rollback(); ???????????} ???????????throw e; ???????} finally { ???????????session.close(); ???????????sessionFactory.close(); ???????} ???????return user; ???} ???/** ????* @param user ????* ???????????首次保存会生成id ????* @throws Exception ????*/ ???public void save(User user) throws Exception { ???????System.out.println("保存User数据"); ???????SessionFactory sessionFactory = HibernateConfigContext ???????????????.getSessionFactoryInstance(); ???????Session session = sessionFactory.openSession(); ???????Transaction transaction = null; ???????try { ???????????transaction = session.beginTransaction(); ???????????session.save(user); ???????????transaction.commit(); ???????} catch (Exception e) { ???????????// TODO: handle exception ???????????if (transaction != null) { ???????????????transaction.rollback(); ???????????} ???????????throw e; ???????} finally { ???????????session.close(); ???????????sessionFactory.close(); ???????} ???} ???/** ????* @param user ????* ???????????已知id的User实例。
 ????* @throws Exception ????*/ ???public void update(User user) throws Exception { ???????SessionFactory sessionFactory = HibernateConfigContext ???????????????.getSessionFactoryInstance(); ???????Session session = sessionFactory.openSession(); ???????Transaction transaction = null; ???????try { ???????????transaction = session.beginTransaction(); ???????????session.update(user); ???????????transaction.commit(); ???????} catch (Exception e) { ???????????// TODO: handle exception ???????????if (transaction != null) { ???????????????transaction.rollback(); ???????????} ???????????throw e; ???????} finally { ???????????session.close(); ???????????sessionFactory.close(); ???????} ???} ???/** ????* @param user ????* ???????????要删除的user,已经保存到数据库的,id分配 ????* @throws Exception ????*/ ???public void delete(User user) throws Exception { ???????SessionFactory sessionFactory = HibernateConfigContext ???????????????.getSessionFactoryInstance(); ???????Session session = sessionFactory.openSession(); ???????Transaction transaction = null; ???????try { ???????????transaction = session.beginTransaction(); ???????????session.delete("User", user); ???????????transaction.commit(); ???????} catch (Exception e) { ???????????// TODO: handle exception ???????????if (transaction != null) { ???????????????transaction.rollback(); ???????????} ???????????throw e; ???????} finally { ???????????session.close(); ???????????sessionFactory.close(); ???????} ???}}

Junit測试程序：

public class UserTest extends TestCase { ???public UserTest(String name) { ???????super(name); ???} ???protected void setUp() throws Exception { ???????super.setUp(); ???} ???protected void tearDown() throws Exception { ???????super.tearDown(); ???} ???public void testSave() { ???????UserDao userDao=new UserDao(); ???????User user=new User(); ???????user.setEmailName("tyhj_sf@163.com"); ???????user.setEmailPassword("ty123456789"); ???????try { ???????????userDao.save(user); ???????} catch (Exception e) { ???????????// TODO Auto-generated catch block ???????????e.printStackTrace(); ???????} ???} ???public void testQueryById() { ???????UserDao userDao=new UserDao(); ???????User user=new User(); ???????user.setId(1L); ???????user.setEmailName("tyhj_sf@163.com"); ???????user.setEmailPassword("ty123456789"); ???????try { ???????????assertEquals(user,userDao.queryById(1)); ???????} catch (Exception e) { ???????????// TODO Auto-generated catch block ???????????e.printStackTrace(); ???????} ???} ???public void testUpdate() { ???????UserDao userDao=new UserDao(); ???????User user=new User(); ???????user.setId(1L); ???????user.setEmailName("tyhj_sf@163.com"); ???????user.setEmailPassword("aaasss"); ???????try { ???????????userDao.update(user); ???????????assertEquals(user,userDao.queryById(1)); ???????} catch (Exception e) { ???????????// TODO Auto-generated catch block ???????????e.printStackTrace(); ???????} ???} ???public void testDelete() { ???????UserDao userDao=new UserDao(); ???????User user=new User(); ???????user.setId(1L); ???????user.setEmailName("tyhj_sf@163.com"); ???????user.setEmailPassword("aaasss"); ???????try { ???????????userDao.delete(user); ???????????assertNull(userDao.queryById(1)); ???????} catch (Exception e) { ???????????// TODO Auto-generated catch block ???????????e.printStackTrace(); ???????} ???}}

很多其它的数据库其它操作參照以上測试用例写就可以。Session类提供了大量方便的操作方法接口，能够參考javadoc文档使用。