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org/apache/commons/configuration/DefaultFileSystem.java
/*
 * 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.commons.configuration;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.io.InputStream;
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.io.FileOutputStream;
import java.io.FileNotFoundException;
import java.net.URL;
import java.net.URLConnection;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;

/**
 * FileSystem that uses java.io.File or HttpClient
 @since 1.7
 @author <a
 * href="http://commons.apache.org/configuration/team-list.html">Commons Configuration team</a>
 */
public class DefaultFileSystem extends FileSystem
{
    /**
     * The Log for diagnostic messages.
     */
    private Log log = LogFactory.getLog(DefaultFileSystem.class);

    public InputStream getInputStream(String basePath, String fileName)
        throws ConfigurationException
    {
        try
        {
            URL url = ConfigurationUtils.locate(this, basePath, fileName);

            if (url == null)
            {
                throw new ConfigurationException("Cannot locate configuration source " + fileName);
            }
            return getInputStream(url);
        }
        catch (ConfigurationException e)
        {
            throw e;
        }
        catch (Exception e)
        {
            throw new ConfigurationException("Unable to load the configuration file " + fileName, e);
        }
    }

    public InputStream getInputStream(URL urlthrows ConfigurationException
    {
        // throw an exception if the target URL is a directory
        File file = ConfigurationUtils.fileFromURL(url);
        if (file != null && file.isDirectory())
        {
            throw new ConfigurationException("Cannot load a configuration from a directory");
        }

        try
        {
            return url.openStream();
        }
        catch (Exception e)
        {
            throw new ConfigurationException("Unable to load the configuration from the URL " + url, e);
        }
    }

    public OutputStream getOutputStream(URL urlthrows ConfigurationException
    {
        // file URLs have to be converted to Files since FileURLConnection is
        // read only (http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4191800)
        File file = ConfigurationUtils.fileFromURL(url);
        if (file != null)
        {
            return getOutputStream(file);
        }
        else
        {
            // for non file URLs save through an URLConnection
            OutputStream out;
            try
            {
                URLConnection connection = url.openConnection();
                connection.setDoOutput(true);

                // use the PUT method for http URLs
                if (connection instanceof HttpURLConnection)
                {
                    HttpURLConnection conn = (HttpURLConnectionconnection;
                    conn.setRequestMethod("PUT");
                }

                out = connection.getOutputStream();

                // check the response code for http URLs and throw an exception if an error occured
                if (connection instanceof HttpURLConnection)
                {
                    out = new HttpOutputStream(out, (HttpURLConnectionconnection);
                }
                return out;
            }
            catch (IOException e)
            {
                throw new ConfigurationException("Could not save to URL " + url, e);
            }
        }
    }

    public OutputStream getOutputStream(File filethrows ConfigurationException
    {
        try
        {
            // create the file if necessary
            createPath(file);
            return new FileOutputStream(file);
        }
        catch (FileNotFoundException e)
        {
            throw new ConfigurationException("Unable to save to file " + file, e);
        }
    }

    public String getPath(File file, URL url, String basePath, String fileName)
    {
        String path = null;
        // if resource was loaded from jar file may be null
        if (file != null)
        {
            path = file.getAbsolutePath();
        }

        // try to see if file was loaded from a jar
        if (path == null)
        {
            if (url != null)
            {
                path = url.getPath();
            }
            else
            {
                try
                {
                    path = getURL(basePath, fileName).getPath();
                }
                catch (Exception e)
                {
                    // simply ignore it and return null
                    ;
                }
            }
        }

        return path;
    }

    public String getBasePath(String path)
    {
        URL url;
        try
        {
            url = getURL(null, path);
            return ConfigurationUtils.getBasePath(url);
        }
        catch (Exception e)
        {
            return null;
        }
    }

    public String getFileName(String path)
    {
        URL url;
        try
        {
            url = getURL(null, path);
            return ConfigurationUtils.getFileName(url);
        }
        catch (Exception e)
        {
            return null;
        }
    }


    public URL getURL(String basePath, String filethrows MalformedURLException
    {
        File f = new File(file);
        if (f.isAbsolute()) // already absolute?
        {
            return ConfigurationUtils.toURL(f);
        }

        try
        {
            if (basePath == null)
            {
                return new URL(file);
            }
            else
            {
                URL base = new URL(basePath);
                return new URL(base, file);
            }
        }
        catch (MalformedURLException uex)
        {
            return ConfigurationUtils.toURL(ConfigurationUtils.constructFile(basePath, file));
        }
    }


    public URL locateFromURL(String basePath, String fileName)
    {
        try
        {
            URL url;
            if (basePath == null)
            {
                return new URL(fileName);
                //url = new URL(name);
            }
            else
            {
                URL baseURL = new URL(basePath);
                url = new URL(baseURL, fileName);

                // check if the file exists
                InputStream in = null;
                try
                {
                    in = url.openStream();
                }
                finally
                {
                    if (in != null)
                    {
                        in.close();
                    }
                }
                return url;
            }
        }
        catch (IOException e)
        {
            if (log.isDebugEnabled())
            {
                log.debug("Could not locate file " + fileName + " at " + basePath + ": " + e.getMessage());
            }
            return null;
        }
    }

    /**
     * Create the path to the specified file.
     *
     @param file the target file
     */
    private void createPath(File file)
    {
        if (file != null)
        {
            // create the path to the file if the file doesn't exist
            if (!file.exists())
            {
                File parent = file.getParentFile();
                if (parent != null && !parent.exists())
                {
                    parent.mkdirs();
                }
            }
        }
    }
    /**
     * Wraps the output stream so errors can be detected in the HTTP response.
     @since 1.7
     @author <a
     * href="http://commons.apache.org/configuration/team-list.html">Commons Configuration team</a>
     */
    private static class HttpOutputStream extends VerifiableOutputStream
    {
        /** The wrapped OutputStream */
        private final OutputStream stream;

        /** The HttpURLConnection */
        private final HttpURLConnection connection;

        public HttpOutputStream(OutputStream stream, HttpURLConnection connection)
        {
            this.stream = stream;
            this.connection = connection;
        }

        public void write(byte[] bytesthrows IOException
        {
            stream.write(bytes);
        }

        public void write(byte[] bytes, int i, int i1throws IOException
        {
            stream.write(bytes, i, i1);
        }

        public void flush() throws IOException
        {
            stream.flush();
        }

        public void close() throws IOException
        {
            stream.close();
        }

        public void write(int ithrows IOException
        {
            stream.write(i);
        }

        public String toString()
        {
            return stream.toString();
        }

        public void verify() throws IOException
        {
            if (connection.getResponseCode() >= HttpURLConnection.HTTP_BAD_REQUEST)
            {
                throw new IOException("HTTP Error " + connection.getResponseCode()
                        " " + connection.getResponseMessage());
            }
        }
    }
}