org.springframework.ejb.support.AbstractMessageDrivenBean.java Source code

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Here is the source code for org.springframework.ejb.support.AbstractMessageDrivenBean.java

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/*
 * Copyright 2002-2005 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.support;

import javax.ejb.MessageDrivenBean;
import javax.ejb.MessageDrivenContext;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/** 
 * Convenient superclass for MDBs.
 * Doesn't require JMS, as EJB 2.1 MDBs are no longer
 * JMS-specific: see the AbstractJmsMessageDrivenBean subclass.
 *
 * <p>This class ensures that subclasses have access to the
 * MessageDrivenContext provided by the EJB container, and implement
 * a no argument ejbCreate() method as required by the EJB specification.
 * This ejbCreate() method loads a BeanFactory, before invoking the
 * onEjbCreate() method, which should contain subclass-specific
 * initialization.
 *
 * <p>NB: We cannot use final methods to implement EJB API methods,
 * as this violates the EJB specification. However, there should
 * be no need to override the setMessageDrivenContext() or
 * ejbCreate() methods.
 *
 * @author Rod Johnson
 */
public abstract class AbstractMessageDrivenBean extends AbstractEnterpriseBean implements MessageDrivenBean {

    protected final Log logger = LogFactory.getLog(getClass());

    private MessageDrivenContext messageDrivenContext;

    /**
     * Required lifecycle method. Sets the MessageDriven context.
     * @param messageDrivenContext MessageDrivenContext
     */
    public void setMessageDrivenContext(MessageDrivenContext messageDrivenContext) {
        this.messageDrivenContext = messageDrivenContext;
    }

    /**
     * Convenience method for subclasses to use.
     * @return the MessageDrivenContext passed to this EJB by the EJB container
     */
    protected final MessageDrivenContext getMessageDrivenContext() {
        return messageDrivenContext;
    }

    /**
     * Lifecycle method required by the EJB specification but not the
     * MessageDrivenBean interface. This implementation loads the BeanFactory.
     * <p>Don't override it (although it can't be made final): code initialization
     * in onEjbCreate(), which is called when the BeanFactory is available.
     * <p>Unfortunately we can't load the BeanFactory in setSessionContext(),
     * as resource manager access isn't permitted and the BeanFactory may require it.
     */
    public void ejbCreate() {
        loadBeanFactory();
        onEjbCreate();
    }

    /**
     * Subclasses must implement this method to do any initialization
     * they would otherwise have done in an ejbCreate() method. In contrast
     * to ejbCreate, the BeanFactory will have been loaded here.
     * <p>The same restrictions apply to the work of this method as
     * to an ejbCreate() method.
     */
    protected abstract void onEjbCreate();

}