(21) How Hibernate session is managed in the project

1. The difference between opensession and getcurrentsession

Package com.rk.hibernate.cache;import org.hibernate.session;import org.hibernate.sessionfactory ; import org.hibernate.cfg.configuration;import org.junit.test;public class app_ Sessioninproject{private static sessionfactory sf;static{sf = new configuration ( ). Configure (). addclass (Department.class). addclass (Employee.class). Buildsessionfactory (); @Testpublic  void testsession () {//opensession:   Create a session,  each time a new sessionsession is created  session1 = sf.opensession (); Session session2 = sf.opensession (); System.out.println (Session1 == session2); Session1.close (); Session2.close ();//getcurrentsession  Create or get a session//  thread to create session  //  be sure to configure: <property name= "hibernate.current_session _context_class ">thread</property>session session3 = sf.getcurrentsession (); Session session4 = sf.getcurrentsession (); System.out.priNtln (SESSION3&NBSP;==&NBSP;SESSION4);//  close   "thread-created session, can not close;  thread end session Auto Close"// Session3.close ();//session4.close ();  error, because the same session is closed! }}

2. Use Hibernate Session in Strut2 project

Hibernate.cfg.xml

<! Doctype hibernate-configuration public "-//hibernate/hibernate configuration dtd 3.0// EN "Http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd" >
Hibernateutils.java
Package Com.rk.utils;import Org.hibernate.session;import Org.hibernate.sessionfactory;import Org.hibernate.cfg.configuration;public class Hibernateutils {//Initialize sessionfactoryprivate static sessionfactory SF; static {SF = new Configuration (). Configure (). Buildsessionfactory ();} Create (GET) Sessionpublic static session getsession () {//thread the way the session was created, must be configured//Can not be closed, will automatically shut down. return sf.getcurrentsession ();}}
Sessioninterceptor.java
package com.rk.interceptor;import org.hibernate.session;import com.rk.utils.hibernateutils; import com.opensymphony.xwork2.actioninvocation;import  Com.opensymphony.xwork2.interceptor.abstractinterceptor;/** * session Management Interceptor: *    When you access the action, create a session;  *  action ---> service  --> dao   "Get the session created here"  *  * */public class sessioninterceptor extends  abstractinterceptor {@Overridepublic  string intercept (actioninvocation invocation)  throws Exception {try {// 1.  Create sessionsession session =  First Hibernateutils.getsession ();// 2.  open transaction session.begintransaction ();// 3.  Execute actionstring  result = invocation.invoke ();// 4.  Commit Transaction session.gettransaction (). Commit ();   //  do not need to close session//  return result view return result;}  catch  (Exception e)  {e.printstacktrace ();return  "error";}}} 
Departmentdao.java
Package Com.rk.dao;import Com.rk.entity.dept;import Com.rk.utils.hibernateutils;public class DepartmentDao {/** * primary key query */public Department FindByID (int id) {//Gets session, executes operation return (Department) hibernateutils.getsession (). Get ( Department.class, id);}}

3, Hibernateutil.java
package com.rk.hibernate.utils;import org.hibernate.hibernateexception;import  Org.hibernate.session;import org.hibernate.sessionfactory;import org.hibernate.transaction;import  org.hibernate.cfg.configuration;public class hibernateutil{private static final  sessionfactory sf;private static final threadlocal<session> threadsession  = new ThreadLocal<Session> ();p rivate static final threadlocal< Transaction> threadtransaction = new threadlocal<transaction> (); static{ Configuration cfg = new configuration (); Sf = cfg.configure (). buildSessionFactory ();} Public static session getsession () {session session = threadsession.get (); try{//  Open a new Session, if this thread has none yetif  ( Session == null) {Session = sf.opeNsession (); Threadsession.set (session);}} catch  (hibernateexception e) {throw new runtimeexception (e);} Return session;} Public static void closesession () {try{session session = threadsession.get (); Threadsession.set (NULL);if  (Session != null && session.isopen ()) { Session.close ();}} catch  (hibernateexception e) {throw new runtimeexception (e);}} Public static void begintransaction () {transaction tx = threadtransaction.get (); try{if  (tx == null) {tx = getsession (). BeginTransaction (); Threadtransaction.set (tx);}} catch  (hibernateexception e) {throw new runtimeexception (e);}} Public static void committransaction () {transaction tx = threadtransaction.get (); try{if  (tx != null && !tx.wascommitted ()  && ! Tx.wasrolledback ()) {tx.commit (); threadtransaction.Set (null);}} catch  (hibernateexception e) {rollbacktransaction ();}} Public static void rollbacktransaction () {Transaction tx = threadtransaction.get ( );try{if  (tx != null && !tx.wascommitted ()  && ! Tx.wasrolledback ()) {threadtransaction.set (null); Tx.rollback ();}} catch  (Hibernateexception ex) {throw new runtimeexception (ex);} Finally{closesession ();}}}

Filter filters
public void DoFilter (ServletRequest request,servletresponse response,filterchain chain) throws IOException, Servlet        Exception {try {chain.dofilter (request, response);    Hibernateutil.committransaction ();    } finally {hibernateutil.closesession (); }}

DAO
public void Execute () {//Get values from request try {hibernateutil.begintransaction ();         Session session = Hibernateutil.getsession ();     Forward to success.jsp page} catch (Hibernateexception ex) {throw new Infrastructureexception (ex); } catch (Exception ex) {//Throw application specific Exception}}




(21) How Hibernate session is managed in the project