ExifTextExtractor.java

/**
 *  OpenKM, Open Document Management System (http://www.openkm.com)
 *  Copyright (c) 2006-2011  Paco Avila & Josep Llort
 *
 *  No bytes were intentionally harmed during the development of this application.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *  
 *  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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

package com.openkm.extractor;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.io.StringReader;
import java.util.Iterator;

import org.apache.jackrabbit.extractor.AbstractTextExtractor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.drew.imaging.ImageMetadataReader;
import com.drew.imaging.ImageProcessingException;
import com.drew.metadata.Directory;
import com.drew.metadata.Metadata;
import com.drew.metadata.MetadataException;
import com.drew.metadata.Tag;

/**
 * Text extractor for JPEG image documents.
 * Use java metadata extraction library from 
 * http://www.drewnoakes.com/code/exif/index.html
 */
public class ExifTextExtractor extends AbstractTextExtractor {

    /**
     * Logger instance.
     */
    private static final Logger log = LoggerFactory.getLogger(ExifTextExtractor.class);

    /**
     * Creates a new <code>JpegTextExtractor</code> instance.
     */
    public ExifTextExtractor() {
        super(new String[]{"image/jpeg"});
    }
    
    //-------------------------------------------------------< TextExtractor >

    /**
     * {@inheritDoc}
     */ 
	@SuppressWarnings("unchecked")
	public Reader extractText(InputStream stream, String type, String encoding) throws IOException {
    	try {
    		Metadata metadata = ImageMetadataReader.readMetadata(new BufferedInputStream(stream));
    		Iterator<Directory> directories = metadata.getDirectoryIterator();
    		StringBuffer sb = new StringBuffer();
    		
    		while (directories.hasNext()) {
    			Directory directory = directories.next();
    			Iterator<Tag> tags = directory.getTagIterator();
    			
    			while (tags.hasNext()) {
    				Tag tag = tags.next();
    				sb.append("[");
    				sb.append(tag.getDirectoryName());
    				sb.append("] ");
    				sb.append(tag.getTagName());
    				sb.append(" = ");
    				sb.append(tag.getDescription());
    				sb.append("\n");
    			}
    		}
    		
    		log.debug("TEXT: "+sb.toString());
            return new StringReader(sb.toString());
		} catch (ImageProcessingException e) {
            log.warn("Failed to extract EXIF information", e);
            return new StringReader("");
		} catch (MetadataException e) {
            log.warn("Failed to extract EXIF information", e);
            return new StringReader("");
		} finally {
			stream.close();
        }
    }
}