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The private implementation classes of the Apache MyFaces Core JSF-2.3-next Implementation
There is a newer version: 4.1.0-RC2
/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.myfaces.spi.impl;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.ServiceLoader;
import java.util.Set;
import javax.faces.context.ExternalContext;

import org.apache.myfaces.util.lang.ClassUtils;
import org.apache.myfaces.spi.ServiceProviderFinder;

/**
 * 
 * @author Leonardo Uribe
 * @since 2.0.3
 *
 */
public class DefaultServiceProviderFinder extends ServiceProviderFinder
{
    private static final String META_INF_SERVICES = "META-INF/services/";
    
    private Map> knownServicesMap = null;

    protected Set getURLs(String spiClass)
    {
        // Use LinkedHashSet to preserve iteration order
        Enumeration profiles = null;
        try
        {
            profiles = ClassUtils.getContextClassLoader().getResources(META_INF_SERVICES + spiClass);
        }
        catch (IOException e)
        {
            return null;
        }
        if (null != profiles && profiles.hasMoreElements())
        {
            Set urls = new LinkedHashSet();
            while (profiles.hasMoreElements())
            {
                URL url = profiles.nextElement();
                urls.add(url);
            }
            return urls;
        }
        return Collections.emptySet();
    }

    @Override
    public List getServiceProviderList(String spiClass)
    {
        if (knownServicesMap != null)
        {
            List result = knownServicesMap.get(spiClass);
            if (result != null)
            {
                return result;
            }
        }
        
        Set urls = getURLs(spiClass);
        if (!urls.isEmpty())
        {
            List results = new LinkedList<>();
            for (URL url : urls)
            {
                try
                {
                    try (InputStream is = openStreamWithoutCache(url))
                    {
                        // This code is needed by EBCDIC and other
                        // strange systems.  It's a fix for bugs
                        // reported in xerces
                        BufferedReader rd;
                        try
                        {
                            rd = new BufferedReader(new InputStreamReader(is, "UTF-8"));
                        }
                        catch (java.io.UnsupportedEncodingException e)
                        {
                            rd = new BufferedReader(new InputStreamReader(is));
                        }

                        try
                        {
                            String serviceImplName;
                            while ((serviceImplName = rd.readLine()) != null)
                            {
                                int idx = serviceImplName.indexOf('#');
                                if (idx >= 0)
                                {
                                    serviceImplName = serviceImplName.substring(0, idx);
                                }
                                serviceImplName = serviceImplName.trim();

                                if (serviceImplName.length() != 0)
                                {
                                    results.add(serviceImplName);
                                }
                            }
                        }
                        finally
                        {
                            if (rd != null)
                            {
                                rd.close();
                            }
                        }
                    }
                }
                catch (IOException e)
                {
                    // ignore
                }
            }
            return results;
        }
        return Collections.emptyList();
    }

    private InputStream openStreamWithoutCache(URL url) throws IOException
    {
        URLConnection connection = url.openConnection();
        connection.setUseCaches(false);
        return connection.getInputStream();
    }
    
    @Override
    public  ServiceLoader load(Class spiClass)
    {
        return ServiceLoader.load(spiClass);
    }

    @Override
    public void initKnownServiceProviderMapInfo(ExternalContext ectx, Map> map)
    {
        knownServicesMap = map;
    }
}