MetaInfoExtractor.java

/*
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package com.celements.photo.metadata;

import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.List;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.xwiki.model.reference.DocumentReference;

import com.drew.imaging.jpeg.JpegMetadataReader;
import com.drew.imaging.jpeg.JpegProcessingException;
import com.drew.metadata.Directory;
import com.drew.metadata.Metadata;
import com.drew.metadata.MetadataException;
import com.drew.metadata.Tag;

/**
 * This class provides the metadata saved in a specified image. There are 
 * several methods to get certain parts of the data.
 */
public class MetaInfoExtractor {
  private static Log LOGGER = LogFactory.getFactory().getInstance(MetaInfoExtractor.class
      );
  
  /**
   * Returns an array of Tag elements representing the metainformation,
   * contained in the specified directory of the given file.
   * 
   * @param imageFile The file to extract the data from.
   * @param directory The desired directory's Class.
   * @return An arry of Tags.
   * @throws MetadataException
   */
  public List<Tag> getDirectoryTagsAsTagList(InputStream imageFile, Class directory
      ) throws MetadataException{    
    Metadata metadata = getMetadata(imageFile);
    Directory dir = metadata.getDirectory(directory);
    List<Tag> data = new ArrayList<Tag>();
    for(Tag tag : dir.getTags()) {
      data.add(tag);
    }
    return data;
  }
    
  /**
   * To get all meta tags possibly contained in an image.
   * 
   * @param imageFile File to extract the Metadata from.
   * @return Hashtable containing the directorys data.
   * @throws MetadataException
   */
  public Map<String, String> getAllTags(InputStream imageFile
      ) throws MetadataException{  
    Metadata data = getMetadata(imageFile);
    Map<String, String> tags = new HashMap<String, String>();
    for(Directory dir : data.getDirectories()) {
      tags.putAll(getDirsTags(dir));
    }
    return tags;
  }
  
  /*
   * Extracts the metadata from the image file represented by an InputStream
   * 
   * @param imageFile InputStream of an image file.
   * @return Metadata containied in the specified image.
   */
  Metadata getMetadata(InputStream imageFile){
    Metadata metadata = null;
    try {
      metadata = JpegMetadataReader.readMetadata(imageFile);
    } catch (JpegProcessingException e) {
      LOGGER.error("Not able to load the meta data of " + imageFile, e);
    }
    return metadata;
  }
  
  /*
   * Saves all tags contained in the specified directory to a Hashtable and 
   * returnes them.
   * 
   * @param dir Directory to extract the tags from.
   * @return Hashtable containing th metatags from the Directory.
   * @throws MetadataException
   */
  Hashtable<String, String> getDirsTags(Directory dir) throws MetadataException{
    Hashtable<String, String> metadata = new Hashtable<String, String>();
    for (Tag tag : dir.getTags()) {
      metadata.put(tag.getTagName(), tag.toString());
    }
    return metadata;
  }
}