org.springframework.ejb.access.LocalSlsbInvokerInterceptor Maven / Gradle / Ivy
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/*
* Copyright 2002-2012 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.ejb.access;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import javax.ejb.CreateException;
import javax.ejb.EJBLocalHome;
import javax.ejb.EJBLocalObject;
import javax.naming.NamingException;
import org.aopalliance.intercept.MethodInvocation;
/**
* Invoker for a local Stateless Session Bean.
* Designed for EJB 2.x, but works for EJB 3 Session Beans as well.
*
* Caches the home object, since a local EJB home can never go stale.
* See {@link org.springframework.jndi.JndiObjectLocator} for info on
* how to specify the JNDI location of the target EJB.
*
*
In a bean container, this class is normally best used as a singleton. However,
* if that bean container pre-instantiates singletons (as do the XML ApplicationContext
* variants) you may have a problem if the bean container is loaded before the EJB
* container loads the target EJB. That is because by default the JNDI lookup will be
* performed in the init method of this class and cached, but the EJB will not have been
* bound at the target location yet. The best solution is to set the lookupHomeOnStartup
* property to false, in which case the home will be fetched on first access to the EJB.
* (This flag is only true by default for backwards compatibility reasons).
*
* @author Rod Johnson
* @author Juergen Hoeller
* @see AbstractSlsbInvokerInterceptor#setLookupHomeOnStartup
* @see AbstractSlsbInvokerInterceptor#setCacheHome
*/
public class LocalSlsbInvokerInterceptor extends AbstractSlsbInvokerInterceptor {
private volatile boolean homeAsComponent = false;
/**
* This implementation "creates" a new EJB instance for each invocation.
* Can be overridden for custom invocation strategies.
*
Alternatively, override {@link #getSessionBeanInstance} and
* {@link #releaseSessionBeanInstance} to change EJB instance creation,
* for example to hold a single shared EJB instance.
*/
@Override
public Object invokeInContext(MethodInvocation invocation) throws Throwable {
Object ejb = null;
try {
ejb = getSessionBeanInstance();
Method method = invocation.getMethod();
if (method.getDeclaringClass().isInstance(ejb)) {
// directly implemented
return method.invoke(ejb, invocation.getArguments());
}
else {
// not directly implemented
Method ejbMethod = ejb.getClass().getMethod(method.getName(), method.getParameterTypes());
return ejbMethod.invoke(ejb, invocation.getArguments());
}
}
catch (InvocationTargetException ex) {
Throwable targetEx = ex.getTargetException();
if (logger.isDebugEnabled()) {
logger.debug("Method of local EJB [" + getJndiName() + "] threw exception", targetEx);
}
if (targetEx instanceof CreateException) {
throw new EjbAccessException("Could not create local EJB [" + getJndiName() + "]", targetEx);
}
else {
throw targetEx;
}
}
catch (NamingException ex) {
throw new EjbAccessException("Failed to locate local EJB [" + getJndiName() + "]", ex);
}
catch (IllegalAccessException ex) {
throw new EjbAccessException("Could not access method [" + invocation.getMethod().getName() +
"] of local EJB [" + getJndiName() + "]", ex);
}
finally {
if (ejb instanceof EJBLocalObject) {
releaseSessionBeanInstance((EJBLocalObject) ejb);
}
}
}
/**
* Check for EJB3-style home object that serves as EJB component directly.
*/
@Override
protected Method getCreateMethod(Object home) throws EjbAccessException {
if (this.homeAsComponent) {
return null;
}
if (!(home instanceof EJBLocalHome)) {
// An EJB3 Session Bean...
this.homeAsComponent = true;
return null;
}
return super.getCreateMethod(home);
}
/**
* Return an EJB instance to delegate the call to.
* Default implementation delegates to newSessionBeanInstance.
* @throws NamingException if thrown by JNDI
* @throws InvocationTargetException if thrown by the create method
* @see #newSessionBeanInstance
*/
protected Object getSessionBeanInstance() throws NamingException, InvocationTargetException {
return newSessionBeanInstance();
}
/**
* Release the given EJB instance.
* Default implementation delegates to removeSessionBeanInstance.
* @param ejb the EJB instance to release
* @see #removeSessionBeanInstance
*/
protected void releaseSessionBeanInstance(EJBLocalObject ejb) {
removeSessionBeanInstance(ejb);
}
/**
* Return a new instance of the stateless session bean.
* Can be overridden to change the algorithm.
* @throws NamingException if thrown by JNDI
* @throws InvocationTargetException if thrown by the create method
* @see #create
*/
protected Object newSessionBeanInstance() throws NamingException, InvocationTargetException {
if (logger.isDebugEnabled()) {
logger.debug("Trying to create reference to local EJB");
}
Object ejbInstance = create();
if (logger.isDebugEnabled()) {
logger.debug("Obtained reference to local EJB: " + ejbInstance);
}
return ejbInstance;
}
/**
* Remove the given EJB instance.
* @param ejb the EJB instance to remove
* @see javax.ejb.EJBLocalObject#remove()
*/
protected void removeSessionBeanInstance(EJBLocalObject ejb) {
if (ejb != null && !this.homeAsComponent) {
try {
ejb.remove();
}
catch (Throwable ex) {
logger.warn("Could not invoke 'remove' on local EJB proxy", ex);
}
}
}
}