001: /*
002: * Copyright 2002-2006 the original author or authors.
003: *
004: * Licensed under the Apache License, Version 2.0 (the "License");
005: * you may not use this file except in compliance with the License.
006: * You may obtain a copy of the License at
007: *
008: * http://www.apache.org/licenses/LICENSE-2.0
009: *
010: * Unless required by applicable law or agreed to in writing, software
011: * distributed under the License is distributed on an "AS IS" BASIS,
012: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013: * See the License for the specific language governing permissions and
014: * limitations under the License.
015: */
016:
017: package org.springframework.orm.hibernate;
018:
019: import net.sf.hibernate.FlushMode;
020: import net.sf.hibernate.HibernateException;
021: import net.sf.hibernate.Session;
022: import org.aopalliance.intercept.MethodInterceptor;
023: import org.aopalliance.intercept.MethodInvocation;
024:
025: import org.springframework.transaction.support.TransactionSynchronizationManager;
026:
027: /**
028: * This interceptor binds a new Hibernate Session to the thread before a method
029: * call, closing and removing it afterwards in case of any method outcome.
030: * If there already is a pre-bound Session (e.g. from HibernateTransactionManager,
031: * or from a surrounding Hibernate-intercepted method), the interceptor simply
032: * participates in it.
033: *
034: * <p>Application code must retrieve a Hibernate Session via the
035: * <code>SessionFactoryUtils.getSession</code> method, to be able to detect a
036: * thread-bound Session. It is preferable to use <code>getSession</code> with
037: * allowCreate=false, if the code relies on the interceptor to provide proper
038: * Session handling. Typically, the code will look like as follows:
039: *
040: * <pre>
041: * public void doSomeDataAccessAction() {
042: * Session session = SessionFactoryUtils.getSession(this.sessionFactory, false);
043: * try {
044: * ...
045: * }
046: * catch (HibernateException ex) {
047: * throw SessionFactoryUtils.convertHibernateAccessException(ex);
048: * }
049: * }</pre>
050: *
051: * Note that the application must care about handling HibernateExceptions itself,
052: * preferably via delegating to the <code>SessionFactoryUtils.convertHibernateAccessException</code>
053: * method that converts them to exceptions that are compatible with the
054: * <code>org.springframework.dao</code> exception hierarchy (like HibernateTemplate does).
055: *
056: * <p>Unfortunately, this interceptor cannot convert checked HibernateExceptions
057: * to unchecked dao ones transparently. The intercepted method would have to declare
058: * the checked HibernateException - thus the caller would still have to catch or
059: * rethrow it, even if it will never be thrown if intercepted. Any such exception
060: * will nevertheless get converted by default.
061: *
062: * <p>This class can be considered a declarative alternative to HibernateTemplate's
063: * callback approach. The advantages are:
064: * <ul>
065: * <li>no anonymous classes necessary for callback implementations;
066: * <li>the possibility to throw any application exceptions from within data access code.
067: * </ul>
068: *
069: * <p>The drawbacks are:
070: * <ul>
071: * <li>the dependency on interceptor configuration;
072: * <li>the delegating try/catch blocks.
073: * </ul>
074: *
075: * <p>Note: Spring's Hibernate support in this package requires Hibernate 2.1.
076: * Dedicated Hibernate3 support can be found in a separate package:
077: * <code>org.springframework.orm.hibernate3</code>.
078: *
079: * @author Juergen Hoeller
080: * @since 13.06.2003
081: * @see SessionFactoryUtils#getSession
082: * @see HibernateTransactionManager
083: * @see HibernateTemplate
084: */
085: public class HibernateInterceptor extends HibernateAccessor implements
086: MethodInterceptor {
087:
088: private boolean exceptionConversionEnabled = true;
089:
090: /**
091: * Set whether to convert any HibernateException raised to a Spring DataAccessException,
092: * compatible with the <code>org.springframework.dao</code> exception hierarchy.
093: * <p>Default is "true". Turn this flag off to let the caller receive raw exceptions
094: * as-is, without any wrapping. Note that this means that the DAO methods will have
095: * to declare the checked HibernateException, and callers will be forced to handle it.
096: * @see org.springframework.dao.DataAccessException
097: */
098: public void setExceptionConversionEnabled(
099: boolean exceptionConversionEnabled) {
100: this .exceptionConversionEnabled = exceptionConversionEnabled;
101: }
102:
103: public Object invoke(MethodInvocation methodInvocation)
104: throws Throwable {
105: Session session = getSession();
106: boolean existingTransaction = SessionFactoryUtils
107: .isSessionTransactional(session, getSessionFactory());
108:
109: if (existingTransaction) {
110: logger
111: .debug("Found thread-bound Session for HibernateInterceptor");
112: } else {
113: TransactionSynchronizationManager.bindResource(
114: getSessionFactory(), new SessionHolder(session));
115: }
116:
117: FlushMode previousFlushMode = null;
118: try {
119: previousFlushMode = applyFlushMode(session,
120: existingTransaction);
121: Object retVal = methodInvocation.proceed();
122: flushIfNecessary(session, existingTransaction);
123: return retVal;
124: } catch (HibernateException ex) {
125: if (this .exceptionConversionEnabled) {
126: throw convertHibernateAccessException(ex);
127: } else {
128: throw ex;
129: }
130: } finally {
131: if (existingTransaction) {
132: logger
133: .debug("Not closing pre-bound Hibernate Session after HibernateInterceptor");
134: if (previousFlushMode != null) {
135: session.setFlushMode(previousFlushMode);
136: }
137: } else {
138: TransactionSynchronizationManager
139: .unbindResource(getSessionFactory());
140: SessionFactoryUtils
141: .closeSessionOrRegisterDeferredClose(session,
142: getSessionFactory());
143: }
144: }
145: }
146:
147: /**
148: * Return a Session for use by this interceptor.
149: * @see SessionFactoryUtils#getSession
150: */
151: protected Session getSession() {
152: return SessionFactoryUtils.getSession(getSessionFactory(),
153: getEntityInterceptor(), getJdbcExceptionTranslator());
154: }
155:
156: }
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