001/* 002 * Copyright 2002-2012 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 * https://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 017package org.springframework.ejb.access; 018 019import java.lang.reflect.InvocationTargetException; 020import java.lang.reflect.Method; 021import javax.ejb.CreateException; 022import javax.ejb.EJBLocalHome; 023import javax.ejb.EJBLocalObject; 024import javax.naming.NamingException; 025 026import org.aopalliance.intercept.MethodInvocation; 027 028/** 029 * Invoker for a local Stateless Session Bean. 030 * Designed for EJB 2.x, but works for EJB 3 Session Beans as well. 031 * 032 * <p>Caches the home object, since a local EJB home can never go stale. 033 * See {@link org.springframework.jndi.JndiObjectLocator} for info on 034 * how to specify the JNDI location of the target EJB. 035 * 036 * <p>In a bean container, this class is normally best used as a singleton. However, 037 * if that bean container pre-instantiates singletons (as do the XML ApplicationContext 038 * variants) you may have a problem if the bean container is loaded before the EJB 039 * container loads the target EJB. That is because by default the JNDI lookup will be 040 * performed in the init method of this class and cached, but the EJB will not have been 041 * bound at the target location yet. The best solution is to set the lookupHomeOnStartup 042 * property to false, in which case the home will be fetched on first access to the EJB. 043 * (This flag is only true by default for backwards compatibility reasons). 044 * 045 * @author Rod Johnson 046 * @author Juergen Hoeller 047 * @see AbstractSlsbInvokerInterceptor#setLookupHomeOnStartup 048 * @see AbstractSlsbInvokerInterceptor#setCacheHome 049 */ 050public class LocalSlsbInvokerInterceptor extends AbstractSlsbInvokerInterceptor { 051 052 private volatile boolean homeAsComponent = false; 053 054 055 /** 056 * This implementation "creates" a new EJB instance for each invocation. 057 * Can be overridden for custom invocation strategies. 058 * <p>Alternatively, override {@link #getSessionBeanInstance} and 059 * {@link #releaseSessionBeanInstance} to change EJB instance creation, 060 * for example to hold a single shared EJB instance. 061 */ 062 @Override 063 public Object invokeInContext(MethodInvocation invocation) throws Throwable { 064 Object ejb = null; 065 try { 066 ejb = getSessionBeanInstance(); 067 Method method = invocation.getMethod(); 068 if (method.getDeclaringClass().isInstance(ejb)) { 069 // directly implemented 070 return method.invoke(ejb, invocation.getArguments()); 071 } 072 else { 073 // not directly implemented 074 Method ejbMethod = ejb.getClass().getMethod(method.getName(), method.getParameterTypes()); 075 return ejbMethod.invoke(ejb, invocation.getArguments()); 076 } 077 } 078 catch (InvocationTargetException ex) { 079 Throwable targetEx = ex.getTargetException(); 080 if (logger.isDebugEnabled()) { 081 logger.debug("Method of local EJB [" + getJndiName() + "] threw exception", targetEx); 082 } 083 if (targetEx instanceof CreateException) { 084 throw new EjbAccessException("Could not create local EJB [" + getJndiName() + "]", targetEx); 085 } 086 else { 087 throw targetEx; 088 } 089 } 090 catch (NamingException ex) { 091 throw new EjbAccessException("Failed to locate local EJB [" + getJndiName() + "]", ex); 092 } 093 catch (IllegalAccessException ex) { 094 throw new EjbAccessException("Could not access method [" + invocation.getMethod().getName() + 095 "] of local EJB [" + getJndiName() + "]", ex); 096 } 097 finally { 098 if (ejb instanceof EJBLocalObject) { 099 releaseSessionBeanInstance((EJBLocalObject) ejb); 100 } 101 } 102 } 103 104 /** 105 * Check for EJB3-style home object that serves as EJB component directly. 106 */ 107 @Override 108 protected Method getCreateMethod(Object home) throws EjbAccessException { 109 if (this.homeAsComponent) { 110 return null; 111 } 112 if (!(home instanceof EJBLocalHome)) { 113 // An EJB3 Session Bean... 114 this.homeAsComponent = true; 115 return null; 116 } 117 return super.getCreateMethod(home); 118 } 119 120 /** 121 * Return an EJB instance to delegate the call to. 122 * Default implementation delegates to newSessionBeanInstance. 123 * @throws NamingException if thrown by JNDI 124 * @throws InvocationTargetException if thrown by the create method 125 * @see #newSessionBeanInstance 126 */ 127 protected Object getSessionBeanInstance() throws NamingException, InvocationTargetException { 128 return newSessionBeanInstance(); 129 } 130 131 /** 132 * Release the given EJB instance. 133 * Default implementation delegates to removeSessionBeanInstance. 134 * @param ejb the EJB instance to release 135 * @see #removeSessionBeanInstance 136 */ 137 protected void releaseSessionBeanInstance(EJBLocalObject ejb) { 138 removeSessionBeanInstance(ejb); 139 } 140 141 /** 142 * Return a new instance of the stateless session bean. 143 * Can be overridden to change the algorithm. 144 * @throws NamingException if thrown by JNDI 145 * @throws InvocationTargetException if thrown by the create method 146 * @see #create 147 */ 148 protected Object newSessionBeanInstance() throws NamingException, InvocationTargetException { 149 if (logger.isDebugEnabled()) { 150 logger.debug("Trying to create reference to local EJB"); 151 } 152 Object ejbInstance = create(); 153 if (logger.isDebugEnabled()) { 154 logger.debug("Obtained reference to local EJB: " + ejbInstance); 155 } 156 return ejbInstance; 157 } 158 159 /** 160 * Remove the given EJB instance. 161 * @param ejb the EJB instance to remove 162 * @see javax.ejb.EJBLocalObject#remove() 163 */ 164 protected void removeSessionBeanInstance(EJBLocalObject ejb) { 165 if (ejb != null && !this.homeAsComponent) { 166 try { 167 ejb.remove(); 168 } 169 catch (Throwable ex) { 170 logger.warn("Could not invoke 'remove' on local EJB proxy", ex); 171 } 172 } 173 } 174 175}