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 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * 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
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 */
package org.jboss.shrinkwrap.api.classloader;

import java.io.Closeable;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLClassLoader;
import java.net.URLConnection;
import java.net.URLStreamHandler;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;

import org.jboss.shrinkwrap.api.Archive;
import org.jboss.shrinkwrap.api.ArchivePath;
import org.jboss.shrinkwrap.api.ArchivePaths;
import org.jboss.shrinkwrap.api.Node;
import org.jboss.shrinkwrap.api.asset.Asset;

Extension that will create a ClassLoader based on a Array of Archives. When done, call close() to free resources. 
Author:
Aslak Knutsen, ALR/**
 * Extension that will create a ClassLoader based on a Array of Archives. When done, call
 * {@link ShrinkWrapClassLoader#close()} to free resources.
 *
 * @author <a href="mailto:aslak@redhat.com">Aslak Knutsen</a>
 * @author <a href="mailto:andrew.rubinger@jboss.org">ALR</a>
 */
public class ShrinkWrapClassLoader extends URLClassLoader implements Closeable {
    // -------------------------------------------------------------------------------------||
    // Class Members ----------------------------------------------------------------------||
    // -------------------------------------------------------------------------------------||

    
Logger
/**
     * Logger
     */
    private static final Logger log = Logger.getLogger(ShrinkWrapClassLoader.class.getName());

    
Empty String
/**
     * Empty String
     */
    private static final String EMPTY = "";

    // -------------------------------------------------------------------------------------||
    // Instance Members -------------------------------------------------------------------||
    // -------------------------------------------------------------------------------------||

    
List of all streams opened, such that they may be closed in close(). Guarded by "this". /**
     * List of all streams opened, such that they may be closed in {@link ShrinkWrapClassLoader#close()}. Guarded by
     * "this".
     */
    private final List<InputStream> openedStreams = new ArrayList<InputStream>();

    // -------------------------------------------------------------------------------------||
    // Constructors -----------------------------------------------------------------------||
    // -------------------------------------------------------------------------------------||

    
Constructs a new ShrinkWrapClassLoader for the specified Archives using the default delegation parent ClassLoader. The Archives will be searched in the order specified for classes and resources after first searching in the parent class loader. 
Params:
archives –  the Archives from which to load classes and resources/**
     * Constructs a new ShrinkWrapClassLoader for the specified {@link Archive}s using the default delegation parent
     * <code>ClassLoader</code>. The {@link Archive}s will be searched in the order specified for classes and resources
     * after first searching in the parent class loader.
     *
     * @param archives
     *            the {@link Archive}s from which to load classes and resources
     */
    public ShrinkWrapClassLoader(final Archive<?>... archives) {
        super(new URL[] {});

        if (archives == null) {
            throw new IllegalArgumentException("Archives must be specified");
        }
        addArchives(archives);
    }

    
Constructs a new ShrinkWrapClassLoader for the given Archives. The Archives will be searched in the order specified for classes and resources after first searching in the specified parent class loader. 
Params:
parent – 
           the parent class loader for delegation
archives –  the Archives from which to load classes and resources/**
     * Constructs a new ShrinkWrapClassLoader for the given {@link Archive}s. The {@link Archive}s will be searched in
     * the order specified for classes and resources after first searching in the specified parent class loader.
     *
     * @param parent
     *            the parent class loader for delegation
     * @param archives
     *            the {@link Archive}s from which to load classes and resources
     */
    public ShrinkWrapClassLoader(final ClassLoader parent, final Archive<?>... archives) {
        super(new URL[] {}, parent);

        if (archives == null) {
            throw new IllegalArgumentException("Archives must be specified");
        }
        addArchives(archives);
    }

    private void addArchives(final Archive<?>[] archives) {
        for (final Archive<?> archive : archives) {
            addArchive(archive);
        }
    }

    private void addArchive(final Archive<?> archive) {
        try {
            addURL(new URL(null, "archive:" + archive.getName() + "/", new URLStreamHandler() {
                @Override
                protected URLConnection openConnection(final URL u) throws IOException {
                    return new URLConnection(u) {
                        @Override
                        public void connect() throws IOException {
                        }

                        @Override
                        public InputStream getInputStream() throws IOException {
                            final ArchivePath path = convertToArchivePath(u);
                            final Node node = archive.get(path);

                            // SHRINKWRAP-308
                            if (node == null) {
                                // We've asked for a path that doesn't exist
                                throw new FileNotFoundException("Requested path: " + path + " does not exist in "
                                    + archive.toString());
                            }

                            final Asset asset = node.getAsset();

                            // SHRINKWRAP-306
                            if (asset == null) {
                                // This is a directory, so return null InputStream to denote as such
                                return null;
                            }

                            final InputStream input = asset.openStream();
                            synchronized (this) {
                                openedStreams.add(input);
                            }
                            return input;

                        }

                        private ArchivePath convertToArchivePath(URL url) {
                            String path = url.getPath();
                            path = path.replace(archive.getName(), EMPTY);

                            return ArchivePaths.create(path);
                        }
                    };
                }
            }));
        } catch (Exception e) {
            throw new RuntimeException("Could not create URL for archive: " + archive.getName(), e);
        }
    }

    public void close() throws IOException {
        synchronized (this) {
            for (InputStream stream : openedStreams) {
                try {
                    stream.close();
                } catch (Exception e) {
                    log.warning("Could not close opened inputstream: " + e);
                }
            }
            openedStreams.clear();
        }
    }
}