Hibernate——编程式事务 小强斋

编程式事务

一、getCurrentSession()与openSession()的区别？
 * 采用getCurrentSession()创建的session会绑定到当前线程中，而采用openSession()创建的session则不会
 * 采用getCurrentSession()创建的session在commit或rollback时会自动关闭，而采用openSession()创建的session必须手动关闭

二、使用getCurrentSession()需要在hibernate.cfg.xml文件中加入如下配置：
 * 如果使用的是本地事务（jdbc事务）
 <property name="hibernate.current_session_context_class">thread</property>
 * 如果使用的是全局事务（jta事务）
 <property name="hibernate.current_session_context_class">jta</property>    

三、例子：模拟日志管理（添加用户时，写入日志）

因为事务是session.beginTransaction();由Session开启的，所有添加用户和相应的日志，必须在一个事务中，那么就必须使用同一个Seesion，传递太麻烦。采用getCurrentSession()创建的session会绑定到当前线程中变量ThreadLocal中。

User.java

package com.ncepu.usermgr.model;

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

	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;
	}
}

User.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.ncepu.usermgr.model">
	<class name="User" table="t_user">
		<id name="id">
			<generator class="native"/>
		</id>
		<property name="name"/>
	</class>
</hibernate-mapping>

Log.java

package com.ncepu.usermgr.model;

import java.util.Date;

public class Log {
	
	private int id;
	
	//操作日志、安全日志、事件日志
	private String type;
	
	private String detail;
	
	private Date time;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getType() {
		return type;
	}

	public void setType(String type) {
		this.type = type;
	}

	public String getDetail() {
		return detail;
	}

	public void setDetail(String detail) {
		this.detail = detail;
	}

	public Date getTime() {
		return time;
	}

	public void setTime(Date time) {
		this.time = time;
	}
}

Log.hbm.xml

<hibernate-mapping package="com.ncepu.usermgr.model">
	<class name="Log" table="t_log">
		<id name="id">
			<generator class="native"/>
		</id>
		<property name="type"/>
		<property name="detail"/>
		<property name="time"/>
	</class>
</hibernate-mapping>

UserManager接口

package com.ncepu.usermgr.manager;

import com.ncepu.usermgr.model.User;

public interface UserManager {
	
	public void addUser(User user);
}

UserManagerImpl实现类

package com.ncepu.usermgr.manager;

import java.util.Date;

import org.hibernate.Session;

import com.ncepu.usermgr.model.Log;
import com.ncepu.usermgr.model.User;
import com.ncepu.usermgr.util.HibernateUtils;

public class UserManagerImpl implements UserManager {

	public void addUser(User user) {
		Session session = null;
		try {
			//session = HibernateUtils.getSession();
			session = HibernateUtils.getSessionFactory().getCurrentSession();
			session.beginTransaction();
			
			session.save(user);

			Integer.parseInt("asdfsdfsfsd");
			Log log = new Log();
			log.setType("安全日志");
			log.setDetail("xxx进入系统");
			log.setTime(new Date());

			LogManager logManager = new LogManagerImpl();
			logManager.addLog(log);

			session.getTransaction().commit();
		}catch(Exception e) {
			e.printStackTrace();
			session.getTransaction().rollback();
//		}finally {
//			HibernateUtils.closeSession(session);
		}
	}
}

LogManager接口

package com.ncepu.usermgr.manager;

import com.ncepu.usermgr.model.Log;

public interface LogManager {
	
	public void addLog(Log log);
}

LogManagerImpl实现类

package com.ncepu.usermgr.manager;

import com.ncepu.usermgr.model.Log;
import com.ncepu.usermgr.util.HibernateUtils;

public class LogManagerImpl implements LogManager {

	public void addLog(Log log) {
		HibernateUtils.getSessionFactory().getCurrentSession().save(log);
	}

}

Client.java

package com.ncepu.usermgr.client;

import com.ncepu.usermgr.manager.UserManager;
import com.ncepu.usermgr.manager.UserManagerImpl;
import com.ncepu.usermgr.model.User;

public class Client {

	public static void main(String[] args) {
		User user = new User();
		user.setName("张三");
		
		UserManager userManager = new UserManagerImpl();
		userManager.addUser(user);
	}
}

工具类SessionFactory

package com.ncepu.usermgr.util;

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

public class HibernateUtils {

	private static SessionFactory factory;
	
	static {
		try {
			Configuration cfg = new Configuration().configure();
			factory = cfg.buildSessionFactory();
		}catch(Exception e) {
			e.printStackTrace();
		}
	}
	
	public static SessionFactory getSessionFactory() {
		return factory;
	}
	
	public static Session getSession() {
		return factory.openSession();
	}
	
	public static void closeSession(Session session) {
		if (session != null) {
			if (session.isOpen()) {
				session.close();
			}
		}
	}
}

导入数据库工具类

package com.ncepu.usermgr.util;

import org.hibernate.cfg.Configuration;
import org.hibernate.tool.hbm2ddl.SchemaExport;

public class ExportDB {

	public static void main(String[] args) {
		
		//读取hibernate.cfg.xml文件
		Configuration cfg = new Configuration().configure();
		
		SchemaExport export = new SchemaExport(cfg);
		
		export.create(true, true);
	}
}

hibernate.cfg.xml配置文件

<!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.connection.url">jdbc:mysql://localhost/spring_hibernate_1</property>
		<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
		<property name="hibernate.connection.username">root</property>
		<property name="hibernate.connection.password">admin</property>
		<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
		<property name="hibernate.show_sql">true</property>
		<property name="hibernate.current_session_context_class">thread</property>
		<!-- 
		<property name="hibernate.current_session_context_class">jta</property>
		 -->		
		<mapping resource="com/ncepu/usermgr/model/User.hbm.xml"/>
		<mapping resource="com/ncepu/usermgr/model/Log.hbm.xml"/>
	</session-factory>
</hibernate-configuration>