org.sigmah.server.dao.hibernate.TransactionalInterceptor.java Source code

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Here is the source code for org.sigmah.server.dao.hibernate.TransactionalInterceptor.java

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/*
 * All Sigmah code is released under the GNU General Public License v3
 * See COPYRIGHT.txt and LICENSE.txt.
 */

package org.sigmah.server.dao.hibernate;

import javax.persistence.EntityManager;
import javax.persistence.EntityTransaction;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.google.inject.Inject;
import com.google.inject.Injector;

/**
 * MethodInterceptor that implements declarative transaction management.
 * See {@link org.sigmah.server.dao.Transactional}
 *
 * @author Alex Bertram
 */
public class TransactionalInterceptor implements MethodInterceptor {

    /**
     * Logger.
     */
    private static final Log log = LogFactory.getLog(TransactionalInterceptor.class);

    private Injector injector;

    @Inject
    public void setInjector(Injector injector) {
        this.injector = injector;
    }

    @Override
    public Object invoke(MethodInvocation methodInvocation) throws Throwable {
        EntityManager em = injector.getInstance(EntityManager.class);
        EntityTransaction tx = em.getTransaction();

        //allow joining of transactions if there is an enclosing @Transactional method
        if (tx.isActive()) {

            if (log.isDebugEnabled()) {
                log.debug("[invoke] Transaction already active, just proceed the method.");
            }

            return methodInvocation.proceed();
        }

        tx.begin();

        if (log.isDebugEnabled()) {
            log.debug("[invoke] Begins an entity transaction.");
        }

        Object result = attemptInvocation(methodInvocation, tx);

        // everything was normal so commit the txn (do not move into try block as it interferes
        // with the advised method's throwing semantics)
        tx.commit();

        if (log.isDebugEnabled()) {
            log.debug("[invoke] Commits the transaction.");
        }

        return result;
    }

    private Object attemptInvocation(MethodInvocation methodInvocation, EntityTransaction tx) throws Throwable {
        try {
            return methodInvocation.proceed();
        } catch (Exception e) {
            // rollback database to original state
            tx.rollback();

            //propagate whatever exception is thrown anyway
            throw e;
        }
    }
}