001/* 002 * Copyright 2002-2017 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; 021 022import javax.ejb.CreateException; 023import javax.ejb.EJBLocalHome; 024import javax.ejb.EJBLocalObject; 025import javax.naming.NamingException; 026 027import org.aopalliance.intercept.MethodInvocation; 028 029import org.springframework.lang.Nullable; 030 031/** 032 * Invoker for a local Stateless Session Bean. 033 * Designed for EJB 2.x, but works for EJB 3 Session Beans as well. 034 * 035 * <p>Caches the home object, since a local EJB home can never go stale. 036 * See {@link org.springframework.jndi.JndiObjectLocator} for info on 037 * how to specify the JNDI location of the target EJB. 038 * 039 * <p>In a bean container, this class is normally best used as a singleton. However, 040 * if that bean container pre-instantiates singletons (as do the XML ApplicationContext 041 * variants) you may have a problem if the bean container is loaded before the EJB 042 * container loads the target EJB. That is because by default the JNDI lookup will be 043 * performed in the init method of this class and cached, but the EJB will not have been 044 * bound at the target location yet. The best solution is to set the lookupHomeOnStartup 045 * property to false, in which case the home will be fetched on first access to the EJB. 046 * (This flag is only true by default for backwards compatibility reasons). 047 * 048 * @author Rod Johnson 049 * @author Juergen Hoeller 050 * @see AbstractSlsbInvokerInterceptor#setLookupHomeOnStartup 051 * @see AbstractSlsbInvokerInterceptor#setCacheHome 052 */ 053public class LocalSlsbInvokerInterceptor extends AbstractSlsbInvokerInterceptor { 054 055 private volatile boolean homeAsComponent = false; 056 057 058 /** 059 * This implementation "creates" a new EJB instance for each invocation. 060 * Can be overridden for custom invocation strategies. 061 * <p>Alternatively, override {@link #getSessionBeanInstance} and 062 * {@link #releaseSessionBeanInstance} to change EJB instance creation, 063 * for example to hold a single shared EJB instance. 064 */ 065 @Override 066 @Nullable 067 public Object invokeInContext(MethodInvocation invocation) throws Throwable { 068 Object ejb = null; 069 try { 070 ejb = getSessionBeanInstance(); 071 Method method = invocation.getMethod(); 072 if (method.getDeclaringClass().isInstance(ejb)) { 073 // directly implemented 074 return method.invoke(ejb, invocation.getArguments()); 075 } 076 else { 077 // not directly implemented 078 Method ejbMethod = ejb.getClass().getMethod(method.getName(), method.getParameterTypes()); 079 return ejbMethod.invoke(ejb, invocation.getArguments()); 080 } 081 } 082 catch (InvocationTargetException ex) { 083 Throwable targetEx = ex.getTargetException(); 084 if (logger.isDebugEnabled()) { 085 logger.debug("Method of local EJB [" + getJndiName() + "] threw exception", targetEx); 086 } 087 if (targetEx instanceof CreateException) { 088 throw new EjbAccessException("Could not create local EJB [" + getJndiName() + "]", targetEx); 089 } 090 else { 091 throw targetEx; 092 } 093 } 094 catch (NamingException ex) { 095 throw new EjbAccessException("Failed to locate local EJB [" + getJndiName() + "]", ex); 096 } 097 catch (IllegalAccessException ex) { 098 throw new EjbAccessException("Could not access method [" + invocation.getMethod().getName() + 099 "] of local EJB [" + getJndiName() + "]", ex); 100 } 101 finally { 102 if (ejb instanceof EJBLocalObject) { 103 releaseSessionBeanInstance((EJBLocalObject) ejb); 104 } 105 } 106 } 107 108 /** 109 * Check for EJB3-style home object that serves as EJB component directly. 110 */ 111 @Override 112 protected Method getCreateMethod(Object home) throws EjbAccessException { 113 if (this.homeAsComponent) { 114 return null; 115 } 116 if (!(home instanceof EJBLocalHome)) { 117 // An EJB3 Session Bean... 118 this.homeAsComponent = true; 119 return null; 120 } 121 return super.getCreateMethod(home); 122 } 123 124 /** 125 * Return an EJB instance to delegate the call to. 126 * Default implementation delegates to newSessionBeanInstance. 127 * @throws NamingException if thrown by JNDI 128 * @throws InvocationTargetException if thrown by the create method 129 * @see #newSessionBeanInstance 130 */ 131 protected Object getSessionBeanInstance() throws NamingException, InvocationTargetException { 132 return newSessionBeanInstance(); 133 } 134 135 /** 136 * Release the given EJB instance. 137 * Default implementation delegates to removeSessionBeanInstance. 138 * @param ejb the EJB instance to release 139 * @see #removeSessionBeanInstance 140 */ 141 protected void releaseSessionBeanInstance(EJBLocalObject ejb) { 142 removeSessionBeanInstance(ejb); 143 } 144 145 /** 146 * Return a new instance of the stateless session bean. 147 * Can be overridden to change the algorithm. 148 * @throws NamingException if thrown by JNDI 149 * @throws InvocationTargetException if thrown by the create method 150 * @see #create 151 */ 152 protected Object newSessionBeanInstance() throws NamingException, InvocationTargetException { 153 if (logger.isDebugEnabled()) { 154 logger.debug("Trying to create reference to local EJB"); 155 } 156 Object ejbInstance = create(); 157 if (logger.isDebugEnabled()) { 158 logger.debug("Obtained reference to local EJB: " + ejbInstance); 159 } 160 return ejbInstance; 161 } 162 163 /** 164 * Remove the given EJB instance. 165 * @param ejb the EJB instance to remove 166 * @see javax.ejb.EJBLocalObject#remove() 167 */ 168 protected void removeSessionBeanInstance(@Nullable EJBLocalObject ejb) { 169 if (ejb != null && !this.homeAsComponent) { 170 try { 171 ejb.remove(); 172 } 173 catch (Throwable ex) { 174 logger.warn("Could not invoke 'remove' on local EJB proxy", ex); 175 } 176 } 177 } 178 179}