org.frontcache.hystrix.fr.FallbackResolverFactory.java Source code

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Here is the source code for org.frontcache.hystrix.fr.FallbackResolverFactory.java

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/**
 *        Copyright 2017 Eternita LLC
 *
 *  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.frontcache.hystrix.fr;

import org.apache.http.client.HttpClient;
import org.frontcache.FCConfig;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class FallbackResolverFactory {

    private static Logger logger = LoggerFactory.getLogger(FallbackResolverFactory.class);

    private FallbackResolverFactory() {
    }

    private static FallbackResolver instance;

    public static FallbackResolver getInstance() {
        if (null == instance) {
            throw new RuntimeException("FallbackResolver is not initialized.");
        }
        return instance;
    }

    public static FallbackResolver init(HttpClient client) {
        if (null == instance) {
            instance = getFallbackResolver();
            instance.init(client);
        }
        return instance;
    }

    /**
     * 
     * @return
     */
    private static FallbackResolver getFallbackResolver() {
        String implStr = FCConfig.getProperty("front-cache.fallback-resolver.impl");
        if (null == implStr) {
            logger.info("Default implementation is loaded: " + FileBasedFallbackResolver.class.getCanonicalName());
            return new FileBasedFallbackResolver();
        }

        try {

            @SuppressWarnings("rawtypes")
            Class clazz = Class.forName(implStr);
            Object obj = clazz.newInstance();
            if (null != obj && obj instanceof FallbackResolver) {
                logger.info("FallbackResolver implementation loaded: " + implStr);
                FallbackResolver fallbackResolver = (FallbackResolver) obj;

                return fallbackResolver;
            }
        } catch (Exception ex) {
            logger.error("Cant instantiate " + implStr + ". Default implementation is loaded: "
                    + FileBasedFallbackResolver.class.getCanonicalName());
            return new FileBasedFallbackResolver();
        }

        return new FileBasedFallbackResolver();
    }

    public static void destroy() {
        instance = null;
        return;
    }
}