com.acmeair.web.ServiceLocator.java Source code

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Here is the source code for com.acmeair.web.ServiceLocator.java

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/*******************************************************************************
* Copyright (c) 2013 IBM Corp.
*
* 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 com.acmeair.web;

import java.util.concurrent.atomic.AtomicReference;

import javax.naming.NamingException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import com.acmeair.web.config.WXSDirectAppConfig;

public class ServiceLocator {

    public static String REPOSITORY_LOOKUP_KEY = "com.acmeair.repository.type";
    final ApplicationContext ctx;
    private static Logger logger = LoggerFactory.getLogger(ServiceLocator.class);

    private static AtomicReference<ServiceLocator> singletonServiceLocator = new AtomicReference<ServiceLocator>();

    static ServiceLocator instance() {
        if (singletonServiceLocator.get() == null) {
            synchronized (singletonServiceLocator) {
                if (singletonServiceLocator.get() == null) {
                    singletonServiceLocator.set(new ServiceLocator());
                }
            }
        }
        return singletonServiceLocator.get();
    }

    private ServiceLocator() {
        String type = null;
        String lookup = REPOSITORY_LOOKUP_KEY.replace('.', '/');
        javax.naming.Context context = null;
        javax.naming.Context envContext;
        try {
            context = new javax.naming.InitialContext();
            envContext = (javax.naming.Context) context.lookup("java:comp/env");
            if (envContext != null)
                type = (String) envContext.lookup(lookup);
        } catch (NamingException e) {
            // e.printStackTrace();
        }

        if (type != null) {
            logger.info("Found repository in web.xml:" + type);
        } else if (context != null) {
            try {
                type = (String) context.lookup(lookup);
                if (type != null)
                    logger.info("Found repository in server.xml:" + type);
            } catch (NamingException e) {
                // e.printStackTrace();
            }
        }

        if (type == null) {
            type = System.getProperty(REPOSITORY_LOOKUP_KEY);
            if (type != null)
                logger.info("Found repository in jvm property:" + type);
            else {
                type = System.getenv(REPOSITORY_LOOKUP_KEY);
                if (type != null)
                    logger.info("Found repository in environment property:" + type);
            }
        }

        // TODO:  Later add back in other implementations
        type = "wxsdirect";
        logger.info("Using default repository :" + type);
        ctx = new AnnotationConfigApplicationContext(WXSDirectAppConfig.class);
    }

    public static <T> T getService(Class<T> clazz) {
        return instance().ctx.getBean(clazz);
    }
}