com.tc.util.factory.AbstractFactory.java Source code

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Here is the source code for com.tc.util.factory.AbstractFactory.java

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/*
 *
 *  The contents of this file are subject to the Terracotta Public 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://terracotta.org/legal/terracotta-public-license.
 *
 *  Software distributed under the License is distributed on an "AS IS" basis,
 *  WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for
 *  the specific language governing rights and limitations under the License.
 *
 *  The Covered Software is Terracotta Core.
 *
 *  The Initial Developer of the Covered Software is
 *  Terracotta, Inc., a Software AG company
 *
 */
package com.tc.util.factory;

import org.apache.commons.io.IOUtils;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;

public abstract class AbstractFactory {
    public static AbstractFactory getFactory(String id, Class<?> defaultImpl) {
        String factoryClassName = findFactoryClassName(id);
        AbstractFactory factory = null;

        if (factoryClassName != null) {
            try {
                factory = (AbstractFactory) Class.forName(factoryClassName).newInstance();
            } catch (Exception e) {
                throw new RuntimeException("Could not instantiate '" + factoryClassName + "'", e);
            }
        }

        if (factory == null) {
            try {
                factory = (AbstractFactory) defaultImpl.newInstance();
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }

        return factory;
    }

    private static String findFactoryClassName(String id) {
        String serviceId = "META-INF/services/" + id;
        InputStream is = null;

        try {
            ClassLoader cl = AbstractFactory.class.getClassLoader();
            if (cl != null) {
                is = cl.getResourceAsStream(serviceId);
            }

            if (is == null) {
                return System.getProperty(id);
            }

            BufferedReader rd;
            try {
                rd = new BufferedReader(new InputStreamReader(is, "UTF-8"));
            } catch (UnsupportedEncodingException e) {
                throw new RuntimeException(e);
            }

            String factoryClassName = null;
            try {
                factoryClassName = rd.readLine();
                rd.close();
            } catch (IOException x) {
                return System.getProperty(id);
            }

            if (factoryClassName != null && !"".equals(factoryClassName)) {
                return factoryClassName;
            }

            return System.getProperty(id);
        } finally {
            IOUtils.closeQuietly(is);
        }
    }
}