FileResourceLoader.java

/*
 * This program is free software; you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
 * Foundation.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
 * or from the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * Copyright (c) 2006 - 2009 Pentaho Corporation and Contributors.  All rights reserved.
 */

package org.pentaho.reporting.libraries.resourceloader.loader.file;

import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.pentaho.reporting.libraries.resourceloader.ResourceData;
import org.pentaho.reporting.libraries.resourceloader.ResourceKey;
import org.pentaho.reporting.libraries.resourceloader.ResourceKeyCreationException;
import org.pentaho.reporting.libraries.resourceloader.ResourceKeyData;
import org.pentaho.reporting.libraries.resourceloader.ResourceKeyUtils;
import org.pentaho.reporting.libraries.resourceloader.ResourceLoader;
import org.pentaho.reporting.libraries.resourceloader.ResourceLoadingException;
import org.pentaho.reporting.libraries.resourceloader.ResourceException;

/**
 * Creation-Date: 05.04.2006, 14:17:56
 *
 * @author Thomas Morgner
 */
public class FileResourceLoader implements ResourceLoader
{
  public static final String SCHEMA_NAME = FileResourceLoader.class.getName();
  private static final Log logger = LogFactory.getLog(FileResourceLoader.class);

  public FileResourceLoader()
  {
  }

  /**
   * Checks, whether this resource loader implementation was responsible for
   * creating this key.
   *
   * @param key
   * @return
   */
  public boolean isSupportedKey(final ResourceKey key)
  {
    if (key == null)
    {
      throw new NullPointerException();
    }
    if (SCHEMA_NAME.equals(key.getSchema()))
    {
      return true;
    }
    return false;
  }

  /**
   * Creates a new resource key from the given object and the factory keys.
   *
   * @param value
   * @param factoryKeys
   * @return the created key.
   * @throws org.pentaho.reporting.libraries.resourceloader.ResourceKeyCreationException
   *          if creating the key failed.
   */
  public ResourceKey createKey(final Object value, final Map factoryKeys) throws ResourceKeyCreationException
  {
    if (value instanceof File)
    {
      final File f = (File) value;
      if (f.exists() && f.isFile())
      {
        return new ResourceKey(SCHEMA_NAME, f, factoryKeys);
      }
    }
    else if (value instanceof String)
    {
      final File f = new File(String.valueOf(value));
      if (f.exists() && f.isFile())
      {
        return new ResourceKey(SCHEMA_NAME, f, factoryKeys);
      }
    }

    return null;
  }

  /**
   * Derives a new resource key from the given key. If neither a path nor new
   * factory-keys are given, the parent key is returned.
   *
   * @param parent      the parent
   * @param path        the derived path (can be null).
   * @param factoryKeys the optional factory keys (can be null).
   * @return the derived key.
   * @throws org.pentaho.reporting.libraries.resourceloader.ResourceKeyCreationException
   *          if the key cannot be derived for any reason.
   */
  public ResourceKey deriveKey(final ResourceKey parent, final String path, final Map factoryKeys)
      throws ResourceKeyCreationException
  {
    if (isSupportedKey(parent) == false)
    {
      throw new ResourceKeyCreationException("Assertation: Unsupported parent key type");
    }

    try
    {
      final File target;
      if (path != null)
      {
        final File parentResource = (File) parent.getIdentifier();
        target = new File(parentResource.getCanonicalFile().getParentFile(), path);
        if (target.exists() == false || target.isFile() == false)
        {
          throw new ResourceKeyCreationException("Malformed value: " + path + " (" + target + ')');
        }

      }
      else
      {
        target = (File) parent.getIdentifier();
      }

      final Map map;
      if (factoryKeys != null)
      {
        map = new HashMap();
        map.putAll(parent.getFactoryParameters());
        map.putAll(factoryKeys);
      }
      else
      {
        map = parent.getFactoryParameters();
      }
      return new ResourceKey(parent.getSchema(), target, map);
    }
    catch (IOException ioe)
    {
      throw new ResourceKeyCreationException("Failed to create key", ioe);
    }
  }

  public URL toURL(final ResourceKey key)
  {
    if (key == null)
    {
      throw new NullPointerException();
    }
    if (isSupportedKey(key) == false)
    {
      throw new IllegalArgumentException("Key format is not recognized.");
    }

    final File file = (File) key.getIdentifier();
    try
    {
      return file.toURL();
    }
    catch (MalformedURLException e)
    {
      return null;
    }
  }

  public ResourceData load(final ResourceKey key) throws ResourceLoadingException
  {
    if (isSupportedKey(key) == false)
    {
      throw new ResourceLoadingException("Key format is not recognized.");
    }
    return new FileResourceData(key);
  }

  /**
   * Generates a String representation of the ResourceKey specified.
   * TODO: implement
   * @param bundleKey
   * @param key
   */
  public String serialize(final ResourceKey bundleKey, final ResourceKey key) throws ResourceException
  {
    // Validate the parameter
    if (key == null)
    {
      throw new NullPointerException("The ResourceKey can not be null");
    }
    if (isSupportedKey(key) == false)
    {
      throw new IllegalArgumentException("Key format is not recognized.");
    }
    if (!(key.getIdentifier() instanceof File))
    {
      throw new IllegalArgumentException("ResourceKey is invalid - identifier is not a File object");
    }

    // Log information
    logger.debug("Serializing a File Resource Key...");
    if (key.getParent() != null)
    {
      throw new ResourceException
          ("Unable to serialize a File-ResourceKey with a parent. This type is not expected to have a parent.");
    }

    // Create a string version of the identifier
    try
    {
      final File file = (File) key.getIdentifier();
      final String strIdentifier = file.getCanonicalPath();
      final String result = ResourceKeyUtils.createStringResourceKey
          (key.getSchema().toString(), strIdentifier, key.getFactoryParameters());
      logger.debug("Serialized File Resource Key: [" + result + "]");
      return result;
    }
    catch (IOException ioe)
    {
      throw new IllegalArgumentException("Could not determine cononical path to file specified in ResourceKey: "
          + ioe.getMessage());
    }
  }

  /**
   * Generates a String representation of the ResourceKey specified.
   * TODO: implement
   */
  public ResourceKey deserialize(final ResourceKey bundleKey, String stringKey) throws ResourceKeyCreationException
  {
    // Parse the data
    ResourceKeyData keyData = ResourceKeyUtils.parse(stringKey);

    // Validate the data
    if (SCHEMA_NAME.equals(keyData.getSchema()) == false)
    {
      throw new ResourceKeyCreationException("Serialized version of key does not contain correct schema");
    }

    // Create a new file based on the path provided
    final File file = new File(keyData.getIdentifier());

    // Return a newly created key based on the parameters we loaded
    return createKey(file, keyData.getFactoryParameters());
  }

  public boolean isSupportedDeserializer(String data)
  {
    return SCHEMA_NAME.equals(ResourceKeyUtils.readSchemaFromString(data));
  }
}