用Filter对Hibernate的session进行管理

关键字: hibernate, session
，Filter
hibernate中的Session关系到对数据库的增删查改等基本的数据存取操作.对Session进行有效的维护,就像是在jdbc编程中对JDBC collection的维护.

在struts+hibernate的方案中,常常利用过滤器(Filter)对session进行管理,以实现session在线程范围内的共享.为什
么仅仅实现线程内的共享,是因为,不能把session用于多线程,否则会出现意外.在线程范围内实现sesion的共享.避免了session的频繁的
创建和销毁.我看到有的程序中,在单个方法内,打开session,执行.关闭session.这显然没有在一次会话中有效的利用session

下面的方案是.通过建立一个过滤器,以实现对sesion的共享:

Java代码


package


com.cs_oj.filter;

import


java.io.IOException;

import


java.text.DateFormat;

import


java.text.SimpleDateFormat;

import


java.util.Date;

import


javax.servlet.Filter;

import


javax.servlet.FilterChain;

import


javax.servlet.FilterConfig;

import


javax.servlet.ServletException;

import


javax.servlet.ServletRequest;

import


javax.servlet.ServletResponse;

import


javax.servlet.http.HttpServletRequest;

import


javax.servlet.http.HttpServletResponse;

import


javax.servlet.http.HttpSession;

import


org.apache.commons.logging.Log;

import


org.apache.commons.logging.LogFactory;

import


org.hibernate.Session;

import


org.hibernate.Transaction;

import


com.cs_oj.data.dao.HibernateSessionFactory;

public


class


HibernateSessionFilter
implements


Filter {

private


static


final


Log log = LogFactory.getLog(HibernateSessionFilter.
class


);

public


void


destroy() {

// TODO Auto-generated method stub

}

public


void


doFilter(ServletRequest arg0, ServletResponse arg1,

FilterChain chain)
throws


IOException, ServletException {

log.debug(
"HibernateSessionFilter start"

);

Date date=
new


Date();

DateFormat df=
new


SimpleDateFormat(
"yyyy-MM-dd '时间--'HH:mm:ss"

);

System.out.println(
"----当前时间:"

+df.format(date)+
"----"

);

System.out.println(
"----------HibernateSessionFilter start-----------"

);

//利用HibernateSessionFactory, 得到当 前线程中的session对象..HibernateSessionFactory的代码利用了ThreadLocal模式..详见..HibernateSessionFactory

Session session=HibernateSessionFactory.getSession();

Transaction tx=session.beginTransaction();
//开始事务

log.debug(
"HibernateSessionFilter begin doChain"

);

HttpServletResponse response=(HttpServletResponse)arg1;

try


{

chain.doFilter(arg0, arg1);

//没有异常,则提交

try{


tx.commit();

}

catch


(Exception e){

try


{

tx.commit();

}
catch


(RuntimeException ex){

System.out.println(
"HibernateSessionFilter rollback() failed"

);

}

}

}
catch


(Exception e) {

e.printStackTrace();

tx.rollback();
//出现异常,回滚

//response.sendRedirect("error.jsp");

}

finally


{

HibernateSessionFactory.closeSession();

}

}

}

package com.cs_oj.filter;

import java.io.IOException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hibernate.Session;
import org.hibernate.Transaction;

import com.cs_oj.data.dao.HibernateSessionFactory;

public class HibernateSessionFilter implements Filter {
private static final Log log = LogFactory.getLog(HibernateSessionFilter.class);
public void destroy() {
// TODO Auto-generated method stub

}

public void doFilter(ServletRequest arg0, ServletResponse arg1,
FilterChain chain) throws IOException, ServletException {
log.debug("HibernateSessionFilter start");
Date date=new Date();
DateFormat df=new SimpleDateFormat("yyyy-MM-dd '时间--'HH:mm:ss");
System.out.println("----当前时间:"+df.format(date)+"----");
System.out.println("----------HibernateSessionFilter start-----------");

//利用HibernateSessionFactory, 得到当 前线程中的session对象..HibernateSessionFactory的代码利用了ThreadLocal模式..详见..HibernateSessionFactory
Session session=HibernateSessionFactory.getSession();
log.info("HibernateSessionFilter begin transaction");
System.out.println("HibernateSessionFilter begin transaction");
Transaction tx=session.beginTransaction();   //开始事务

log.debug("HibernateSessionFilter begin doChain");
HttpServletResponse response=(HttpServletResponse)arg1;
try{
chain.doFilter(arg0, arg1);

log.debug("HibernateSessionFilter begin commit");
//没有异常,则提交
try{

System.out.println("HibernateSessionFilter begin commit");
tx.commit();
System.out.println("HibernateSessionFilter commit success");

}
catch(Exception e){

System.out.println("HibernateSessionFilter commit failed");
System.out.println("HibernateSessionFilter begin rollback() ");
try{
System.out.println("HibernateSessionFilter begin rollback() ");
tx.rollback();
System.out.println("HibernateSessionFilter rollback() success ");
}catch(RuntimeException ex){
System.out.println("HibernateSessionFilter   rollback() failed");
}
}
}catch (Exception e) {
e.printStackTrace();
System.out.println("chain.doFilter(arg0, arg1) exception accurs ");
System.out.println("HibernateSessionFilter begin rollback() ");
tx.rollback();   //出现异常,回滚
//response.sendRedirect("error.jsp");
}
finally{
log.debug("HibernateSessionFilter end doChain");
System.out.println("HibernateSessionFilter begin close session");
HibernateSessionFactory.closeSession();
System.out.println("*********HibernateSessionFilter close session success*********");
log.debug("HibernateSessionFilter begin close session");
//System.out.println("session.isOpen()="+session.isOpen());
}

}

}

在web.xml文件中对上面的过滤器进行配置.

Xml代码


<
filter
>



<
filter-name
>


hibernateSession
</
filter-name
>



<
filter-class
>


com.cs_oj.filter.HibernateSessionFilter
</
filter-class
>



</
filter
>



<
filter-mapping
>



<
filter-name
>


hibernateSession
</
filter-name
>



<
servlet-name
>


action
</
servlet-name
>



</
filter-mapping
>



<
servlet
>



<
servlet-name
>


action
</
servlet-name
>



<
servlet-class
>


org.apache.struts.action.ActionServlet
</
servlet-class
>



<
init-param
>


.

<
init-param
>



<
param-name
>


config
</
param-name
>



<
param-value
>


/WEB-INF/struts-config.xml
</
param-value
>



</
init-param
>



<
init-param
>



<
param-name
>


debug
</
param-name
>



<
param-value
>


3
</
param-value
>



</
init-param
>



<
init-param
>



<
param-name
>


detail
</
param-name
>



<
param-value
>


3
</
param-value
>



</
init-param
>



<
load-on-startup
>


0
</
load-on-startup
>



</
servlet
>



<
servlet-mapping
>



<
servlet-name
>


action
</
servlet-name
>



<
url-pattern
>


*.do
</
url-pattern
>



</
servlet-mapping
>

<filter>
<filter-name>hibernateSession</filter-name>
<filter-class>com.cs_oj.filter.HibernateSessionFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>hibernateSession</filter-name>
<servlet-name>action</servlet-name>

</filter-mapping>
<servlet>
<servlet-name>action</servlet-name>
<servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
<init-param>.
<init-param>
<param-name>config</param-name>
<param-value>/WEB-INF/struts-config.xml</param-value>
</init-param>
<init-param>
<param-name>debug</param-name>
<param-value>3</param-value>
</init-param>
<init-param>
<param-name>detail</param-name>
<param-value>3</param-value>
</init-param>
<load-on-startup>0</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>action</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping>

则对所有以.do作为后缀名的url,都会被过滤器过滤.在被过滤器过滤的action中,和业务层的方法内,只需要调用
HibernateSessionFactory
的getSession()方法,得到当前线程内的session对象.用完session后,不要关闭session,而且,每次在用session进
行添加和修改操作时,也不需要启动事务.

HibernateSessionFactory.java

Java代码


package


com.cs_oj.data.dao;

import


org.hibernate.HibernateException;

import


org.hibernate.Session;

import


org.hibernate.cfg.Configuration;

public


class


HibernateSessionFactory {

private


static


String CONFIG_FILE_LOCATION =
"/hibernate.cfg.xml"

;

private


static


final


ThreadLocal<Session> threadLocal =
new


ThreadLocal<Session>();

private


static


Configuration configuration =
new


Configuration().configure();

private


static


org.hibernate.SessionFactory sessionFactory;

private


static


String configFile = CONFIG_FILE_LOCATION;

private


HibernateSessionFactory() {

}

public


static


Session getSession()
throws


HibernateException {

Session session = threadLocal.get();

if


(session ==
null


|| !session.isOpen()) {

if


(sessionFactory ==
null


) {

rebuildSessionFactory();

}

session = (sessionFactory !=
null


) ? sessionFactory.openSession()

:
null


;

threadLocal.set(session);

}

return


session;

}

public


static


void


rebuildSessionFactory() {

try


{

sessionFactory = configuration.buildSessionFactory();

}
catch


(Exception e) {

System.err

.println(
"%%%% Error Creating SessionFactory %%%%"

);

e.printStackTrace();

}

}

public


static


void


closeSession()
throws


HibernateException {

Session session = threadLocal.get();

threadLocal.set(
null


);

if


(session !=
null


) {

session.close();

}

}

public


static


org.hibernate.SessionFactory getSessionFactory() {

return


sessionFactory;

}

public


static


void


setConfigFile(String configFile) {

HibernateSessionFactory.configFile = configFile;

sessionFactory =
null


;

}

public


static


Configuration getConfiguration() {

return


configuration;

}

}