1 /**
2 * Copyright 2011, Aiki IT, FotoRenamer
3 * <p/>
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 * <p/>
8 * http://www.apache.org/licenses/LICENSE-2.0
9 * <p/>
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package de.aikiit.fotorenamer.image;
17
18 import com.google.common.base.Strings;
19 import org.apache.commons.imaging.Imaging;
20 import org.apache.commons.imaging.common.ImageMetadata;
21 import org.apache.commons.imaging.formats.jpeg.JpegImageMetadata;
22 import org.apache.commons.imaging.formats.tiff.TiffField;
23 import org.apache.commons.imaging.formats.tiff.constants.ExifTagConstants;
24 import org.apache.commons.imaging.formats.tiff.taginfos.TagInfo;
25 import org.apache.log4j.Logger;
26
27 import java.io.File;
28 import java.io.IOException;
29
30 /**
31 * Helper class to extract metadata from given images. This class uses Apache
32 * Sanslean to perform the metadata extraction itself.
33 */
34 final class MetaDataExtractor {
35 /**
36 * This class' logger.
37 */
38 private static final Logger LOG = Logger.getLogger(MetaDataExtractor.class);
39
40 /**
41 * Constant for an empty string.
42 */
43 private static final String EMPTY_STRING = "";
44
45 /**
46 * Constant for a blank character.
47 */
48 private static final String SPACE = " ";
49
50 /**
51 * Constant for an underscore character.
52 */
53 private static final String UNDERSCORE = "_";
54
55 /**
56 * Constant for a colon.
57 */
58 private static final String COLON = ":";
59
60 /**
61 * Constant for an apostrophe.
62 */
63 private static final String APOSTROPHE = "'";
64
65 /**
66 * Constant to describe a valid length of an EXIF date (currently 21).
67 */
68 private static final int VALID_EXIF_DATE_LENGTH = 21;
69
70 /**
71 * Constructor is not visible to avoid instantiation.
72 */
73 private MetaDataExtractor() {
74 // prevent instantiation of this utility class
75 }
76
77 /**
78 * Returns the requested tag as String from the image file.
79 *
80 * @param image Image file to extract Metadata from.
81 * @param tag Tag to extract from the given file, @see TiffConstants
82 * @return Returns exif tag value, in case of any errors the value is an
83 * empty String.
84 * @throws IOException if file cannot be accessed.
85 */
86 public static String getExifMetadata(final File image,
87 final TagInfo tag)
88 throws IOException {
89 assert image != null : "Parameter image must not be null";
90 assert tag != null : "Parameter tag must not be null";
91
92 String result = EMPTY_STRING;
93 ImageMetadata metadata = Imaging.getMetadata(image);
94
95 if (metadata instanceof JpegImageMetadata) {
96 JpegImageMetadata jpegMetadata = (JpegImageMetadata) metadata;
97 TiffField field = jpegMetadata.findExifValueWithExactMatch(tag);
98 if (field != null) {
99 result = field.getValueDescription();
100 LOG.info("extraction of " + tag.getDescription()
101 + " yields " + result);
102 }
103 }
104 return result == null ? EMPTY_STRING : result;
105 }
106
107 /**
108 * Helper to extract the date this image was created to be used during the
109 * renaming process.
110 * <br>
111 * In the EXIF standard itself the following convention for dates as is
112 * defined: <i> D. Other Tags DateTime The date and time of image creation.
113 * In this standard it is the date and time the file was changed. The format
114 * is "YYYY:MM:DD HH:MM:SS" with time shown in 24-hour format, and the date
115 * and time separated by one blank character [20.H]. When the date and time
116 * are unknown, all the character spaces except colons (":") may be filled
117 * with blank characters, or else the Interoperability field may be filled
118 * with blank characters. The character string length is 20 bytes including
119 * NULL for termination. When the field is left blank, it is treated as
120 * unknown. Tag = 306 (132.H) Type = ASCII Count = 20 Default = none </i>
121 * <p>
122 * If the extracted date value is empty - no new file name is generated.
123 *
124 * @param image Image to extract metadata from.
125 * @return the date this image was created if found, format is
126 * @throws IOException If an error occurs when accessing the image's
127 * metadata.
128 * @see <a href="http://www.exif.org/samples/canon-ixus.html">Canon EXIF
129 * example page</a>
130 * @see <a href="http://www.exif.org/specifications.html">EXIF
131 * specifications</a>
132 * @see <a href="http://www.exif.org/Exif2-2.PDF">EXIF2-2.pdf
133 * specification</a>
134 */
135 public static String generateCreationDateInCorrectFormat(final File image)
136 throws IOException {
137
138 String dateValue =
139 getExifMetadata(image, ExifTagConstants.EXIF_TAG_DATE_TIME_ORIGINAL);
140
141 LOG.info("EXIF date value is: " + dateValue);
142
143 // Invalid length of EXIF metadata, not complying to the standard.
144 if (Strings.isNullOrEmpty(dateValue) || dateValue.length() != VALID_EXIF_DATE_LENGTH) {
145 LOG.info("No valid creation date extracted from file " + image);
146 return EMPTY_STRING;
147 }
148
149 // Date parsing with apache.DateUtils or JDK-DateFormats
150 // does not work due to '-signs in the date string
151 // (unparseable pattern is "'yyyy:MM:dd HH:mm:ss'")
152 // replace special characters to extract digits only
153 dateValue = dateValue.replaceAll(APOSTROPHE, EMPTY_STRING);
154 dateValue = dateValue.replaceAll(COLON, EMPTY_STRING);
155 dateValue = dateValue.replaceAll(SPACE, UNDERSCORE);
156 dateValue += UNDERSCORE;
157 //convert '2011:01:30 13:11:02' to "yyyyMMdd_HHmm_"+fileName
158 dateValue += image.getName();
159
160 LOG.info("Target filename is: " + dateValue);
161 return dateValue;
162 }
163 }