ServiceFactory.java

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package com.sun.faces.spi;

import com.sun.faces.util.Util;
import com.sun.faces.util.FacesLogger;

import javax.faces.FacesException;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.List;
import java.util.Enumeration;
import java.util.ArrayList;
import java.util.Arrays;
import java.net.URL;
import java.net.URLConnection;
import java.io.IOException;
import java.io.InputStream;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

/**
 * <p>
 * Base class for service discovery.
 * </p>
 */
final class ServiceFactoryUtils {

    private static final Logger LOGGER = FacesLogger.APPLICATION.getLogger();
    private static final String[] EMPTY_ARRAY = new String[0];


    // ---------------------------------------------------------- Public Methods


    static Object getProviderFromEntry(String entry, Class<?>[] argumentTypes, Object[] arguments) {

        if (entry == null) {
            return null;
        }

        try {
            Class<?> clazz = Util.loadClass(entry, null);
            Constructor c = clazz.getDeclaredConstructor(argumentTypes);
            if (c == null) {
                throw new FacesException("Unable to find constructor accepting arguments: " + Arrays.toString(arguments));
            }
            return c.newInstance(arguments);
        } catch (ClassNotFoundException | NoSuchMethodException | SecurityException | FacesException | InstantiationException | IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
            if (LOGGER.isLoggable(Level.FINE)) {
                LOGGER.log(Level.FINE, e.toString(), e);
            }
            return null;
        }

    }


    static String[] getServiceEntries(String key) {

        List<String> results = null;
        ClassLoader loader = Thread.currentThread().getContextClassLoader();
        if (loader == null) {
            return EMPTY_ARRAY;
        }

        Enumeration<URL> urls = null;
        String serviceName = "META-INF/services/" + key;
        try {
            urls = loader.getResources(serviceName);
        } catch (IOException ioe) {
            if (LOGGER.isLoggable(Level.SEVERE)) {
                LOGGER.log(Level.SEVERE,
                           ioe.toString(),
                           ioe);
            }
        }

        if (urls != null) {
            InputStream input = null;
            BufferedReader reader = null;
            while (urls.hasMoreElements()) {
                try {
                    if (results == null) {
                        results = new ArrayList<>();
                    }
                    URL url = urls.nextElement();
                    URLConnection conn = url.openConnection();
                    conn.setUseCaches(false);
                    input = conn.getInputStream();
                    if (input != null) {
                        try {
                            reader =
                                  new BufferedReader(new InputStreamReader(input,
                                                                           "UTF-8"));
                        } catch (Exception e) {
                            // The DM_DEFAULT_ENCODING warning is acceptable here
                            // because we explicitly *want* to use the Java runtime's
                            // default encoding.
                            reader =
                                  new BufferedReader(new InputStreamReader(input));
                        }
                        for (String line = reader.readLine();
                             line != null;
                             line = reader.readLine()) {
                            results.add(line.trim());
                        }
                    }
                } catch (Exception e) {
                    if (LOGGER.isLoggable(Level.SEVERE)) {
                        LOGGER.log(Level.SEVERE,
                                   "jsf.spi.provider.cannot_read_service",
                                   new Object[]{serviceName});
                        LOGGER.log(Level.SEVERE,
                                   e.toString(),
                                   e);
                    }
                } finally {
                    if (input != null) {
                        try {
                            input.close();
                        } catch (Exception e) {
                            if (LOGGER.isLoggable(Level.FINEST)) {
                                LOGGER.log(Level.FINEST, "Closing stream", e);
                            }
                        }
                    }
                    if (reader != null) {
                        try {
                            reader.close();
                        } catch (Exception e) {
                            if (LOGGER.isLoggable(Level.FINEST)) {
                                LOGGER.log(Level.FINEST, "Closing stream", e);
                            }
                        }
                    }
                }
            }
        }

        return ((results != null && !results.isEmpty())
                ? results.toArray(new String[results.size()])
                : EMPTY_ARRAY);

    }

}