01: /*
02: * Copyright 2002-2007 the original author or authors.
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
10: * Unless required by applicable law or agreed to in writing, software
11: * distributed under the License is distributed on an "AS IS" BASIS,
12: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13: * See the License for the specific language governing permissions and
14: * limitations under the License.
15: */
16:
17: package org.springframework.ejb.support;
18:
19: import javax.ejb.CreateException;
20: import javax.ejb.EJBException;
21:
22: import org.apache.commons.logging.Log;
23: import org.apache.commons.logging.LogFactory;
24:
25: /**
26: * Convenient superclass for stateless session beans (SLSBs), minimizing
27: * the work involved in implementing an SLSB and preventing common errors.
28: * <b>Note that SLSBs are the most useful kind of EJB.</b>
29: *
30: * <p>As the ejbActivate() and ejbPassivate() methods cannot be invoked
31: * on SLSBs, these methods are implemented to throw an exception and should
32: * not be overriden by subclasses. (Unfortunately the EJB specification
33: * forbids enforcing this by making EJB lifecycle methods final.)
34: *
35: * <p>There should be no need to override the <code>setSessionContext()</code>
36: * or <code>ejbCreate()</code> lifecycle methods.
37: *
38: * <p>Subclasses are left to implement the <code>onEjbCreate()</code> method
39: * to do whatever initialization they wish to do after their BeanFactory has
40: * already been loaded, and is available from the <code>getBeanFactory()</code>
41: * method.
42: *
43: * <p>This class provides the no-arg <code>ejbCreate()</code> method required
44: * by the EJB specification, but not the SessionBean interface, eliminating
45: * a common cause of EJB deployment failure.
46: *
47: * @author Rod Johnson
48: */
49: public abstract class AbstractStatelessSessionBean extends
50: AbstractSessionBean {
51:
52: /** Logger available to subclasses */
53: protected final Log logger = LogFactory.getLog(getClass());
54:
55: /**
56: * This implementation loads the BeanFactory. A BeansException thrown by
57: * loadBeanFactory will simply get propagated, as it is a runtime exception.
58: * <p>Don't override it (although it can't be made final): code your own
59: * initialization in onEjbCreate(), which is called when the BeanFactory
60: * is available.
61: * <p>Unfortunately we can't load the BeanFactory in setSessionContext(),
62: * as resource manager access isn't permitted there - but the BeanFactory
63: * may require it.
64: */
65: public void ejbCreate() throws CreateException {
66: loadBeanFactory();
67: onEjbCreate();
68: }
69:
70: /**
71: * Subclasses must implement this method to do any initialization
72: * they would otherwise have done in an <code>ejbCreate()</code> method.
73: * In contrast to <code>ejbCreate</code>, the BeanFactory will have been loaded here.
74: * <p>The same restrictions apply to the work of this method as
75: * to an <code>ejbCreate()</code> method.
76: * @throws CreateException
77: */
78: protected abstract void onEjbCreate() throws CreateException;
79:
80: /**
81: * @see javax.ejb.SessionBean#ejbActivate(). This method always throws an exception, as
82: * it should not be invoked by the EJB container.
83: */
84: public void ejbActivate() throws EJBException {
85: throw new IllegalStateException(
86: "ejbActivate must not be invoked on a stateless session bean");
87: }
88:
89: /**
90: * @see javax.ejb.SessionBean#ejbPassivate(). This method always throws an exception, as
91: * it should not be invoked by the EJB container.
92: */
93: public void ejbPassivate() throws EJBException {
94: throw new IllegalStateException(
95: "ejbPassivate must not be invoked on a stateless session bean");
96: }
97:
98: }
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