浅谈HIbernate

<?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> ???<!-- 数据库连接配置 --> ???<property name="connection.driver_class">com.mysql.jdbc.Driver</property> ???<property name="connection.url">jdbc:mysql://127.0.0.1:3306/javaee?useUnicode=true&amp;characterEncoding=UTF-8</property> ???<property name="connection.username">用户名</property> ???<property name="connection.password">密码</property> ???<!-- 数据库连接池的大小 --> ???<property name="connection.pool_size">50</property> ????<!-- 每次从数据库中取出并放到JDBC的Statement中的记录条数。Fetch Size设的越大，读数据库的次数越少，速度越快，Fetch Size越小，读数据库的次数越多，速度越慢--> ??????<property name="jdbc.fetch_size">500 </property> ??????<!--批量插入,删除和更新时每次操作的记录数。Batch Size越大，批量操作的向数据库发送Sql的次数越少，速度就越快，同样耗用内存就越大--> ??????<property name="jdbc.batch_size">23 </property> ?????<!-- SQL 方言 --> ???<property name="dialect">org.hibernate.dialect.MySQL5Dialect</property> ???<!-- Enable Hibernate‘s automatic session context management --> ???<property name="current_session_context_class">thread</property> ???<!-- 在控制台输出sql语句 --> ???<property name="show_sql">true</property> ???<!-- 在启动时根据配置更新数据库 --> ???<property name="hbm2ddl.auto">update</property> ????<!--注册我们的实体映射类--> ???<mapping class="com.lwz.hibernate.bean.UserEntity"/></session-factory></hibernate-configuration>/

package com.lwz.hibernate.bean;import org.hibernate.SessionFactory;import org.hibernate.boot.MetadataSources;import org.hibernate.boot.registry.StandardServiceRegistry;import org.hibernate.boot.registry.StandardServiceRegistryBuilder;public class MyHibernate { ???public static SessionFactory sessionFactory; ???static { ???????final StandardServiceRegistry registry = new StandardServiceRegistryBuilder() ???????????????.configure("com/lwz/hibernate/resource/hibernate.cfg.xml").build(); ???????try { ???????????sessionFactory = new MetadataSources(registry).buildMetadata() ???????????????????.buildSessionFactory(); ???????} catch (Exception e) { ???????????StandardServiceRegistryBuilder.destroy(registry); ???????} ???}}

3、实体类定义
package com.lwz.hibernate.bean;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.Id;import javax.persistence.Table;@Entity@Table(name="t_user1")public class UserEntity { ???@Id ???@Column(name="id",length=32) ???private String userId; ???@Column(name="name",length=20) ???private String userName; ???@Column(name="pass",length=20) ???private String password; ???@Column(name="age",length=22) ???private int age; ???public String getUserId() { ???????return userId; ???} ???public void setUserId(String userId) { ???????this.userId = userId; ???} ???public String getUserName() { ???????return userName; ???} ???public void setUserName(String userName) { ???????this.userName = userName; ???} ???public String getPassword() { ???????return password; ???} ???public void setPassword(String password) { ???????this.password = password; ???} ???public int getAge() { ???????return age; ???} ???public void setAge(int age) { ???????this.age = age; ???} ???}

4、测试hibernate基本的增删改查

package com.lwz.hibernate.test;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.junit.Before;
import org.junit.Test;

import com.lwz.hibernate.bean.MyHibernate;
import com.lwz.hibernate.bean.UserEntity;

public class T {
SessionFactory session = null;
@Before
public void config(){
session = MyHibernate.sessionFactory;
}

public Session getSession(){
return session.openSession();
}

@Test
public void saveEntity(){
//獲取session
Session s = this.getSession();
//獲取事務
Transaction tr = s.getTransaction();
tr.begin();//開啟事務
UserEntity user = new UserEntity();
user.setAge(25);
user.setPassword("666666");
user.setUserId("xx002");
user.setUserName("关二哥在此，谁敢不服");
//s.save(user);
//s.update(user);
UserEntity u = s.get(UserEntity.class, "xx001");
UserEntity u2 = s.load(UserEntity.class, "xx002");
//s.delete(u);
System.out.println(u.getUserName());
tr.commit();//事务提交
s.close();//关闭连接
System.out.println(u.getAge());
//懒加载异常
//System.out.println(u2.getUserName());
}

//public static void main(String[] args) {
//
////System.out.println(MyHibernate.sessionFactory.openSession());
//}
}