BeanManagerLocator.java

/*
 * Copyright 2013 Martin Kouba
 *
 * 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.trimou.cdi;

import javax.enterprise.inject.spi.BeanManager;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 *
 * @author Martin Kouba
 */
public class BeanManagerLocator {

    private static final Logger LOGGER = LoggerFactory
            .getLogger(BeanManagerLocator.class);

    private static final String CDI_CLASS_NAME = "javax.enterprise.inject.spi.CDI";

    private static final String[] JNDI_NAMES = { "java:comp/BeanManager",
            "java:comp/env/BeanManager" };

    private static BeanManager extensionProvidedBeanManager = null;

    /**
     * Try to lookup the {@link BeanManager} reference.
     *
     * First try CDI 1.1 preferred way - javax.enterprise.inject.spi.CDI. Then
     * CDI 1.0 compatible way - JNDI lookup. And finally extension provided
     * manager (workaround to support CDI 1.0 and SE).
     *
     * @return {@link BeanManager} instance or <code>null</code>
     */
    public static BeanManager locate() {
        BeanManager beanManager = locateCDI11();
        if (beanManager == null) {
            beanManager = locateJNDI();
        }
        if (beanManager != null) {
            return beanManager;
        } else if (extensionProvidedBeanManager != null) {
            LOGGER.info(
                    "Finally using extension provided BeanManager instance");
            return extensionProvidedBeanManager;
        }
        return null;
    }

    private static BeanManager locateCDI11() {

        BeanManager beanManager = null;
        ClassLoader classLoader = SecurityActions.getContextClassLoader();
        Class<?> cdiClass = null;

        try {
            cdiClass = classLoader.loadClass(CDI_CLASS_NAME);
            LOGGER.info(
                    "CDI 1.1 - using javax.enterprise.inject.spi.CDI to obtain BeanManager instance");
        } catch (ClassNotFoundException | NoClassDefFoundError ignored) {
            // CDI 1.0
        }
        if (cdiClass != null) {
            try {
                Object cdi = SecurityActions.getMethod(cdiClass, "current")
                        .invoke(null);
                beanManager = (BeanManager) SecurityActions
                        .getMethod(cdiClass, "getBeanManager").invoke(cdi);
            } catch (Exception e) {
                // Reflection invocation failed
                LOGGER.warn("Unable to invoke CDI.current().getBeanManager()",
                        e);
            }
        }
        return beanManager;
    }

    private static BeanManager locateJNDI() {
        LOGGER.info("CDI 1.0 - using JNDI to obtain BeanManager instance");
        BeanManager beanManager = null;
        try {
            Context ctx = new InitialContext();
            for (String name : JNDI_NAMES) {
                try {
                    beanManager = (BeanManager) ctx.lookup(name);
                } catch (NamingException e) {
                    // Not found
                    LOGGER.info("Unable to find BeanManager at: {}", name);
                }
                if (beanManager != null) {
                    LOGGER.info("BeanManager found at: {}", name);
                    break;
                }
            }
        } catch (NamingException e) {
            LOGGER.warn(
                    "JNDI lookup failed - unable to create initial context");
        }
        return beanManager;
    }

    static void setExtensionProvidedBeanManager(BeanManager beanManager) {
        extensionProvidedBeanManager = beanManager;
    }

}