Revision bed13665
Added by Cherian Mathew about 11 years ago
| cdmlib-services/src/main/java/eu/etaxonomy/cdm/api/conversation/ConversationHolder.java | ||
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import java.sql.Connection; |
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import java.sql.SQLException; |
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import java.util.ArrayList; |
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import java.util.Iterator; |
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import java.util.List; |
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import javax.sql.DataSource; |
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import org.hibernate.jdbc.Work; |
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import org.springframework.beans.factory.annotation.Autowired; |
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import org.springframework.dao.DataAccessResourceFailureException; |
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import org.springframework.jdbc.datasource.ConnectionHolder; |
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import org.springframework.orm.hibernate4.SessionFactoryUtils; |
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import org.springframework.orm.hibernate4.SessionHolder; |
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import org.springframework.transaction.PlatformTransactionManager; |
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import org.springframework.transaction.TransactionStatus; |
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import org.springframework.transaction.support.TransactionSynchronizationManager; |
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import eu.etaxonomy.cdm.api.service.IService; |
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import eu.etaxonomy.cdm.api.service.ServiceImpl; |
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import eu.etaxonomy.cdm.persistence.hibernate.CdmPostDataChangeObservableListener; |
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/** |
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* This is an implementation of the session-per-conversation pattern for usage |
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* in a Spring context. |
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* This is an implementation of the session-per-conversation pattern for usage in a Spring context. |
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* |
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* The primary aim of this class is to create and maintain sessions across multiple transactions. |
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* It is important to ensure that these (long running) sessions must always behave consistently |
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* with regards to session management behaviour expected by Hibernate. |
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* <p> |
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* This behaviour essentially revolves around the resources map in the {@link org.springframework.transaction.support.TransactionSynchronizationManager TransactionSynchronizationManager}.
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* This resources map contains two entries of interest, |
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* - (Autowired) {@link org.hibernate.SessionFactory} mapped to the {@link org.springframework.orm.hibernate4.SessionHolder}
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* - (Autowired) {@link javax.sql.DataSource} mapped to the {@link org.springframework.jdbc.datasource.ConnectionHolder}
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* <p> |
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* The SessionHolder object itself contains the {@link org.hibernate.Session Session} as well as the {@link org.hibernate.Transaction object.
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* The ConnectionHolder contains the (JDBC) {@link java.sql.Connection Connection} to the database. For every action to do with the
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* transaction object it is required to have both entries present in the resources. Both the session as well as the connection |
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* objects must not be null and the corresponding holders must have their 'synchronizedWithTransaction' flag set to true. |
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* <p> |
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* The default behaviour of the {@link org.springframework.transaction.PlatformTransactionManager PlatformTransactionManager} which in the CDM case is autowired
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* to {@link org.springframework.orm.hibernate4.HibernateTransactionManager HibernateTransactionManager}, is to check these entries
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* when starting a transaction. If this entries do not exist in the resource map then they are created, implying a new session, which |
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* is in fact how hibernate implements the default 'session-per-request' pattern internally. |
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* <p> |
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* Given the above conditions, this class manages long running sessions by providing the following methods, |
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* - {@link #bind()} : binds the session owned by this conversation to the resource map
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* - {@link #startTransaction()} : starts a transaction
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* - {@link #commit()} : commits the current transaction, with the option of restarting a new transaction.
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* - {@link #unbind()} : unbinds the session owned by this conversation from the resource map.
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* - {@link #close()} : closes the session owned by this conversation
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* <p> |
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* With the exception of {@link #unbind()} (which should be called explicitly), the above sequence must be strictly followed to
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* maintain a consistent session state. Even though it is possible to interweave multiple conversations at the same time, for a |
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* specific conversation the above sequence must be followed. |
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* |
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* @see http://www.hibernate.org/42.html |
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* |
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* @author n.hoffmann |
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* @author n.hoffmann,c.mathew
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* @created 12.03.2009 |
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* @version 1.0 |
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*/ |
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public class ConversationHolder{
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public class ConversationHolder {
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private static final Logger logger = Logger.getLogger(ConversationHolder.class); |
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@Autowired |
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private PlatformTransactionManager transactionManager; |
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@Autowired |
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private IService service; |
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/** |
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* This conversations transaction |
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*/ |
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private TransactionStatus transactionStatus; |
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private boolean closed = false; |
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|
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this(); |
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this.dataSource = dataSource; |
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this.sessionFactory = sessionFactory; |
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this.transactionManager = transactionManager; |
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this.transactionManager = transactionManager;
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bind(); |
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if(TransactionSynchronizationManager.hasResource(getDataSource())){
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TransactionSynchronizationManager.unbindResource(getDataSource()); |
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} |
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} |
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/** |
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public void bind() {
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logger.info("Binding resources for ConversationHolder");
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if(TransactionSynchronizationManager.isSynchronizationActive()){
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TransactionSynchronizationManager.clearSynchronization(); |
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} |
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logger.info("Starting new Synchronization in TransactionSynchronizationManager");
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TransactionSynchronizationManager.initSynchronization(); |
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if(TransactionSynchronizationManager.hasResource(getSessionFactory())){
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TransactionSynchronizationManager.unbindResource(getSessionFactory()); |
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} |
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logger.info("Binding Session to TransactionSynchronizationManager: Session: " + getSessionHolder());
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TransactionSynchronizationManager.bindResource(getSessionFactory(), getSessionHolder()); |
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}catch(Exception e){
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} catch(Exception e){
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logger.error("Error binding resources for session", e);
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} |
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} |
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/** |
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* This method has to be called when suspending the current unit of work. The conversation can be later bound again. |
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*/ |
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public void unbind() {
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logger.info("Unbinding resources for ConversationHolder");
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if(TransactionSynchronizationManager.isSynchronizationActive()){
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TransactionSynchronizationManager.clearSynchronization(); |
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} |
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if(isBound()) {
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// unbind the current session. |
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// there is no need to bind a new session, since HibernateTransactionManager will create a new one |
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// if the resource map does not contain one (ditto for the datasource-to-connection entry). |
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TransactionSynchronizationManager.unbindResource(getSessionFactory()); |
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if(TransactionSynchronizationManager.hasResource(getDataSource())){
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TransactionSynchronizationManager.unbindResource(getDataSource()); |
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} |
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} |
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} |
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public SessionHolder getSessionHolder(){
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if(this.sessionHolder == null){
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logger.info("Creating new SessionHolder");
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*/ |
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public boolean isBound(){
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//return sessionHolder != null && longSession != null && longSession.isConnected(); |
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return longSession != null && getSessionFactory().getCurrentSession() == longSession; |
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SessionHolder currentSessionHolder = (SessionHolder)TransactionSynchronizationManager.getResource(getSessionFactory()); |
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return longSession != null && currentSessionHolder != null && getSessionFactory().getCurrentSession() == longSession; |
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} |
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/** |
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logger.warn("We allow only one transaction at the moment but startTransaction " +
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"was called a second time.\nReturning the transaction already associated with this " + |
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"ConversationManager"); |
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}else{
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}else{
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//always safe to remove the datasource-to-connection entry since we |
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// know that HibernateTransactionManager will create a new one |
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if(TransactionSynchronizationManager.hasResource(getDataSource())){
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TransactionSynchronizationManager.unbindResource(getDataSource()); |
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} |
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transactionStatus = transactionManager.getTransaction(definition); |
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logger.info("Transaction started: " + transactionStatus);
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if(getSessionHolder().isRollbackOnly()){
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logger.error("Commiting this session will not work. It has been marked as rollback only.");
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} |
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// if a datasource-to-connection entry already exists in the resource map |
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// then its setSynchronizedWithTransaction should be true, since hibernate has added |
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// this entry. |
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// if the datasource-to-connection entry does not exist then we need to create one |
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// and explicitly setSynchronizedWithTransaction to true. |
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TransactionSynchronizationManager.getResource(getDataSource()); |
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if(!TransactionSynchronizationManager.hasResource(getDataSource())){
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try {
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ConnectionHolder ch = new ConnectionHolder(getDataSource().getConnection()); |
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ch.setSynchronizedWithTransaction(true); |
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TransactionSynchronizationManager.bindResource(getDataSource(),ch); |
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} catch (IllegalStateException e) {
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// TODO Auto-generated catch block |
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e.printStackTrace(); |
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} catch (SQLException e) {
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// TODO Auto-generated catch block |
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e.printStackTrace(); |
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} |
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} |
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// commit the changes |
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transactionManager.commit(transactionStatus); |
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/** |
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* @return the session associated with this conversation manager |
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*/ |
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private Session getSession() {
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public Session getSession() {
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if(longSession == null){
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logger.info("Creating Session: [" + longSession + "]");
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try{
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//TODO still need to check if connection and session() handling still works correctly |
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//after upgrade to hibernate 4. |
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//With hibernate 4 JDBC {@link Connection connection(s)} will be obtained from the
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// configured {@link org.hibernate.service.jdbc.connections.spi.ConnectionProvider}
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//as needed. |
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//Also interesting: http://stackoverflow.com/questions/3526556/session-connection-deprecated-on-hibernate |
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//http://blog-it.hypoport.de/2012/05/10/hibernate-4-migration/ |
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longSession = sessionFactory.openSession(); |
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longSession.setFlushMode(FlushMode.COMMIT); |
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} |
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catch (HibernateException ex) {
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throw new DataAccessResourceFailureException("Could not open Hibernate Session", ex);
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} |
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longSession = getNewSession(); |
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} |
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return longSession; |
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} |
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/** |
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* @return a new session to be managed by this conversation |
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*/ |
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private Session getNewSession() {
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// Interesting: http://stackoverflow.com/questions/3526556/session-connection-deprecated-on-hibernate |
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// Also, http://blog-it.hypoport.de/2012/05/10/hibernate-4-migration/ |
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// This will create a new session which must be explicitly managed by this conversation, which includes |
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// binding / unbinding / closing session as well as starting / committing transactions. |
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Session session = sessionFactory.openSession(); |
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session.setFlushMode(FlushMode.COMMIT); |
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logger.info("Creating Session: [" + longSession + "]");
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return session; |
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} |
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/** |
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* @return the session factory that is bound to this conversation manager |
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*/ |
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private SessionFactory getSessionFactory() {
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public SessionFactory getSessionFactory() {
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return sessionFactory; |
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} |
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|
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* Free resources bound to this conversationHolder |
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*/ |
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public void close(){
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if(getSession().isOpen()) |
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getSession().close(); |
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if(getSession().isOpen()) {
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getSession().close(); |
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unbind(); |
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} |
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longSession = null; |
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sessionHolder = null; |
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closed = true; |
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} |
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public boolean isClosed(){
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return closed; |
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} |
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} |
Also available in: Unified diff
updated to be compatible with hibernate4