org.springframework.ejb.access.AbstractSlsbInvokerInterceptor Maven / Gradle / Ivy
/*
* 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.naming.Context;
import javax.naming.NamingException;
import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.springframework.jndi.JndiObjectLocator;
/**
* Base class for AOP interceptors invoking local or remote Stateless Session Beans.
* Designed for EJB 2.x, but works for EJB 3 Session Beans as well.
*
* Such an interceptor must be the last interceptor in the advice chain.
* In this case, there is no direct target object: The call is handled in a
* special way, getting executed on an EJB instance retrieved via an EJB home.
*
* @author Rod Johnson
* @author Juergen Hoeller
*/
public abstract class AbstractSlsbInvokerInterceptor extends JndiObjectLocator
implements MethodInterceptor {
private boolean lookupHomeOnStartup = true;
private boolean cacheHome = true;
private boolean exposeAccessContext = false;
/**
* The EJB's home object, potentially cached.
* The type must be Object as it could be either EJBHome or EJBLocalHome.
*/
private Object cachedHome;
/**
* The no-arg create() method required on EJB homes, potentially cached.
*/
private Method createMethod;
private final Object homeMonitor = new Object();
/**
* Set whether to look up the EJB home object on startup.
* Default is "true".
*
Can be turned off to allow for late start of the EJB server.
* In this case, the EJB home object will be fetched on first access.
* @see #setCacheHome
*/
public void setLookupHomeOnStartup(boolean lookupHomeOnStartup) {
this.lookupHomeOnStartup = lookupHomeOnStartup;
}
/**
* Set whether to cache the EJB home object once it has been located.
* Default is "true".
*
Can be turned off to allow for hot restart of the EJB server.
* In this case, the EJB home object will be fetched for each invocation.
* @see #setLookupHomeOnStartup
*/
public void setCacheHome(boolean cacheHome) {
this.cacheHome = cacheHome;
}
/**
* Set whether to expose the JNDI environment context for all access to the target
* EJB, i.e. for all method invocations on the exposed object reference.
*
Default is "false", i.e. to only expose the JNDI context for object lookup.
* Switch this flag to "true" in order to expose the JNDI environment (including
* the authorization context) for each EJB invocation, as needed by WebLogic
* for EJBs with authorization requirements.
*/
public void setExposeAccessContext(boolean exposeAccessContext) {
this.exposeAccessContext = exposeAccessContext;
}
/**
* Fetches EJB home on startup, if necessary.
* @see #setLookupHomeOnStartup
* @see #refreshHome
*/
@Override
public void afterPropertiesSet() throws NamingException {
super.afterPropertiesSet();
if (this.lookupHomeOnStartup) {
// look up EJB home and create method
refreshHome();
}
}
/**
* Refresh the cached home object, if applicable.
* Also caches the create method on the home object.
* @throws NamingException if thrown by the JNDI lookup
* @see #lookup
* @see #getCreateMethod
*/
protected void refreshHome() throws NamingException {
synchronized (this.homeMonitor) {
Object home = lookup();
if (this.cacheHome) {
this.cachedHome = home;
this.createMethod = getCreateMethod(home);
}
}
}
/**
* Determine the create method of the given EJB home object.
* @param home the EJB home object
* @return the create method
* @throws EjbAccessException if the method couldn't be retrieved
*/
protected Method getCreateMethod(Object home) throws EjbAccessException {
try {
// Cache the EJB create() method that must be declared on the home interface.
return home.getClass().getMethod("create", (Class[]) null);
}
catch (NoSuchMethodException ex) {
throw new EjbAccessException("EJB home [" + home + "] has no no-arg create() method");
}
}
/**
* Return the EJB home object to use. Called for each invocation.
*
Default implementation returns the home created on initialization,
* if any; else, it invokes lookup to get a new proxy for each invocation.
*
Can be overridden in subclasses, for example to cache a home object
* for a given amount of time before recreating it, or to test the home
* object whether it is still alive.
* @return the EJB home object to use for an invocation
* @throws NamingException if proxy creation failed
* @see #lookup
* @see #getCreateMethod
*/
protected Object getHome() throws NamingException {
if (!this.cacheHome || (this.lookupHomeOnStartup && !isHomeRefreshable())) {
return (this.cachedHome != null ? this.cachedHome : lookup());
}
else {
synchronized (this.homeMonitor) {
if (this.cachedHome == null) {
this.cachedHome = lookup();
this.createMethod = getCreateMethod(this.cachedHome);
}
return this.cachedHome;
}
}
}
/**
* Return whether the cached EJB home object is potentially
* subject to on-demand refreshing. Default is "false".
*/
protected boolean isHomeRefreshable() {
return false;
}
/**
* Prepares the thread context if necessar, and delegates to
* {@link #invokeInContext}.
*/
@Override
public Object invoke(MethodInvocation invocation) throws Throwable {
Context ctx = (this.exposeAccessContext ? getJndiTemplate().getContext() : null);
try {
return invokeInContext(invocation);
}
finally {
getJndiTemplate().releaseContext(ctx);
}
}
/**
* Perform the given invocation on the current EJB home,
* within the thread context being prepared accordingly.
* Template method to be implemented by subclasses.
* @param invocation the AOP method invocation
* @return the invocation result, if any
* @throws Throwable in case of invocation failure
*/
protected abstract Object invokeInContext(MethodInvocation invocation) throws Throwable;
/**
* Invokes the {@code create()} method on the cached EJB home object.
* @return a new EJBObject or EJBLocalObject
* @throws NamingException if thrown by JNDI
* @throws InvocationTargetException if thrown by the create method
*/
protected Object create() throws NamingException, InvocationTargetException {
try {
Object home = getHome();
Method createMethodToUse = this.createMethod;
if (createMethodToUse == null) {
createMethodToUse = getCreateMethod(home);
}
if (createMethodToUse == null) {
return home;
}
// Invoke create() method on EJB home object.
return createMethodToUse.invoke(home, (Object[]) null);
}
catch (IllegalAccessException ex) {
throw new EjbAccessException("Could not access EJB home create() method", ex);
}
}
}