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.rmi.RemoteException; 021 022import javax.ejb.CreateException; 023import javax.ejb.EJBObject; 024import javax.naming.NamingException; 025 026import org.aopalliance.intercept.MethodInvocation; 027 028import org.springframework.beans.factory.DisposableBean; 029import org.springframework.lang.Nullable; 030import org.springframework.remoting.RemoteLookupFailureException; 031import org.springframework.remoting.rmi.RmiClientInterceptorUtils; 032 033/** 034 * Basic invoker for a remote Stateless Session Bean. 035 * Designed for EJB 2.x, but works for EJB 3 Session Beans as well. 036 * 037 * <p>"Creates" a new EJB instance for each invocation, or caches the session 038 * bean instance for all invocations (see {@link #setCacheSessionBean}). 039 * See {@link org.springframework.jndi.JndiObjectLocator} for info on 040 * how to specify the JNDI location of the target EJB. 041 * 042 * <p>In a bean container, this class is normally best used as a singleton. However, 043 * if that bean container pre-instantiates singletons (as do the XML ApplicationContext 044 * variants) you may have a problem if the bean container is loaded before the EJB 045 * container loads the target EJB. That is because by default the JNDI lookup will be 046 * performed in the init method of this class and cached, but the EJB will not have been 047 * bound at the target location yet. The best solution is to set the "lookupHomeOnStartup" 048 * property to "false", in which case the home will be fetched on first access to the EJB. 049 * (This flag is only true by default for backwards compatibility reasons). 050 * 051 * <p>This invoker is typically used with an RMI business interface, which serves 052 * as super-interface of the EJB component interface. Alternatively, this invoker 053 * can also proxy a remote SLSB with a matching non-RMI business interface, i.e. an 054 * interface that mirrors the EJB business methods but does not declare RemoteExceptions. 055 * In the latter case, RemoteExceptions thrown by the EJB stub will automatically get 056 * converted to Spring's unchecked RemoteAccessException. 057 * 058 * @author Rod Johnson 059 * @author Juergen Hoeller 060 * @since 09.05.2003 061 * @see org.springframework.remoting.RemoteAccessException 062 * @see AbstractSlsbInvokerInterceptor#setLookupHomeOnStartup 063 * @see AbstractSlsbInvokerInterceptor#setCacheHome 064 * @see AbstractRemoteSlsbInvokerInterceptor#setRefreshHomeOnConnectFailure 065 */ 066public class SimpleRemoteSlsbInvokerInterceptor extends AbstractRemoteSlsbInvokerInterceptor 067 implements DisposableBean { 068 069 private boolean cacheSessionBean = false; 070 071 @Nullable 072 private Object beanInstance; 073 074 private final Object beanInstanceMonitor = new Object(); 075 076 077 /** 078 * Set whether to cache the actual session bean object. 079 * <p>Off by default for standard EJB compliance. Turn this flag 080 * on to optimize session bean access for servers that are 081 * known to allow for caching the actual session bean object. 082 * @see #setCacheHome 083 */ 084 public void setCacheSessionBean(boolean cacheSessionBean) { 085 this.cacheSessionBean = cacheSessionBean; 086 } 087 088 089 /** 090 * This implementation "creates" a new EJB instance for each invocation. 091 * Can be overridden for custom invocation strategies. 092 * <p>Alternatively, override {@link #getSessionBeanInstance} and 093 * {@link #releaseSessionBeanInstance} to change EJB instance creation, 094 * for example to hold a single shared EJB component instance. 095 */ 096 @Override 097 @Nullable 098 protected Object doInvoke(MethodInvocation invocation) throws Throwable { 099 Object ejb = null; 100 try { 101 ejb = getSessionBeanInstance(); 102 return RmiClientInterceptorUtils.invokeRemoteMethod(invocation, ejb); 103 } 104 catch (NamingException ex) { 105 throw new RemoteLookupFailureException("Failed to locate remote EJB [" + getJndiName() + "]", ex); 106 } 107 catch (InvocationTargetException ex) { 108 Throwable targetEx = ex.getTargetException(); 109 if (targetEx instanceof RemoteException) { 110 RemoteException rex = (RemoteException) targetEx; 111 throw RmiClientInterceptorUtils.convertRmiAccessException( 112 invocation.getMethod(), rex, isConnectFailure(rex), getJndiName()); 113 } 114 else if (targetEx instanceof CreateException) { 115 throw RmiClientInterceptorUtils.convertRmiAccessException( 116 invocation.getMethod(), targetEx, "Could not create remote EJB [" + getJndiName() + "]"); 117 } 118 throw targetEx; 119 } 120 finally { 121 if (ejb instanceof EJBObject) { 122 releaseSessionBeanInstance((EJBObject) ejb); 123 } 124 } 125 } 126 127 /** 128 * Return an EJB component instance to delegate the call to. 129 * <p>The default implementation delegates to {@link #newSessionBeanInstance}. 130 * @return the EJB component instance 131 * @throws NamingException if thrown by JNDI 132 * @throws InvocationTargetException if thrown by the create method 133 * @see #newSessionBeanInstance 134 */ 135 protected Object getSessionBeanInstance() throws NamingException, InvocationTargetException { 136 if (this.cacheSessionBean) { 137 synchronized (this.beanInstanceMonitor) { 138 if (this.beanInstance == null) { 139 this.beanInstance = newSessionBeanInstance(); 140 } 141 return this.beanInstance; 142 } 143 } 144 else { 145 return newSessionBeanInstance(); 146 } 147 } 148 149 /** 150 * Release the given EJB instance. 151 * <p>The default implementation delegates to {@link #removeSessionBeanInstance}. 152 * @param ejb the EJB component instance to release 153 * @see #removeSessionBeanInstance 154 */ 155 protected void releaseSessionBeanInstance(EJBObject ejb) { 156 if (!this.cacheSessionBean) { 157 removeSessionBeanInstance(ejb); 158 } 159 } 160 161 /** 162 * Reset the cached session bean instance, if necessary. 163 */ 164 @Override 165 protected void refreshHome() throws NamingException { 166 super.refreshHome(); 167 if (this.cacheSessionBean) { 168 synchronized (this.beanInstanceMonitor) { 169 this.beanInstance = null; 170 } 171 } 172 } 173 174 /** 175 * Remove the cached session bean instance, if necessary. 176 */ 177 @Override 178 public void destroy() { 179 if (this.cacheSessionBean) { 180 synchronized (this.beanInstanceMonitor) { 181 if (this.beanInstance instanceof EJBObject) { 182 removeSessionBeanInstance((EJBObject) this.beanInstance); 183 } 184 } 185 } 186 } 187 188}