我想从图像（jpg）中读取信息，该图像包含数码相机中的一些额外信息，例如创建日期，焦点，闪光灯关闭，...我如何获得这些信息。
我的第一个想法是。
BufferedImage image = ImageIO.read(filePicture);
if (image().getPropertyNames() != null) {
for (int j = 0; j < image().getPropertyNames().length; j++) {
String key = image().getPropertyNames()[j];
String value = (String) image().getProperty(key);
System.out.println(key + ": " + value);
}
}
但是 getPropertyNames（） 返回 null！
另一个简单的选择是使用元数据提取器：
Metadata metadata = ImageMetadataReader.readMetadata(imagePath);
迭代文件中的所有值：
for (Directory directory : metadata.getDirectories()) {
for (Tag tag : directory.getTags()) {
System.out.println(tag);
}
}
您还可以从特定目录中读取特定值：
// obtain the Exif SubIFD directory
ExifSubIFDDirectory directory
= metadata.getFirstDirectoryOfType(ExifSubIFDDirectory.class);
// query the datetime tag's value
Date date = directory.getDate(ExifSubIFDDirectory.TAG_DATETIME_ORIGINAL);
该库也可供Maven用户使用。
（完全披露：我是这个库的作者）
我建议使用可以读取EXIF数据和其他格式（IPTC，XMP ...）http://commons.apache.org/proper/commons-imaging/
也有一些例子：http://commons.apache.org/proper/commons-imaging/sampleusage.html
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package org.apache.commons.imaging.examples;
import java.io.File;
import java.io.IOException;
import java.util.List;
import org.apache.commons.imaging.ImageReadException;
import org.apache.commons.imaging.Imaging;
import org.apache.commons.imaging.common.ImageMetadata;
import org.apache.commons.imaging.common.ImageMetadata.ImageMetadataItem;
import org.apache.commons.imaging.common.RationalNumber;
import org.apache.commons.imaging.formats.jpeg.JpegImageMetadata;
import org.apache.commons.imaging.formats.tiff.TiffField;
import org.apache.commons.imaging.formats.tiff.TiffImageMetadata;
import org.apache.commons.imaging.formats.tiff.constants.ExifTagConstants;
import org.apache.commons.imaging.formats.tiff.constants.GpsTagConstants;
import org.apache.commons.imaging.formats.tiff.constants.TiffTagConstants;
import org.apache.commons.imaging.formats.tiff.taginfos.TagInfo;
public class MetadataExample {
public static void metadataExample(final File file) throws ImageReadException,
IOException {
// get all metadata stored in EXIF format (ie. from JPEG or TIFF).
final ImageMetadata metadata = Imaging.getMetadata(file);
// System.out.println(metadata);
if (metadata instanceof JpegImageMetadata) {
final JpegImageMetadata jpegMetadata = (JpegImageMetadata) metadata;
// Jpeg EXIF metadata is stored in a TIFF-based directory structure
// and is identified with TIFF tags.
// Here we look for the "x resolution" tag, but
// we could just as easily search for any other tag.
//
// see the TiffConstants file for a list of TIFF tags.
System.out.println("file: " + file.getPath());
// print out various interesting EXIF tags.
printTagValue(jpegMetadata, TiffTagConstants.TIFF_TAG_XRESOLUTION);
printTagValue(jpegMetadata, TiffTagConstants.TIFF_TAG_DATE_TIME);
printTagValue(jpegMetadata,
ExifTagConstants.EXIF_TAG_DATE_TIME_ORIGINAL);
printTagValue(jpegMetadata, ExifTagConstants.EXIF_TAG_DATE_TIME_DIGITIZED);
printTagValue(jpegMetadata, ExifTagConstants.EXIF_TAG_ISO);
printTagValue(jpegMetadata,
ExifTagConstants.EXIF_TAG_SHUTTER_SPEED_VALUE);
printTagValue(jpegMetadata,
ExifTagConstants.EXIF_TAG_APERTURE_VALUE);
printTagValue(jpegMetadata,
ExifTagConstants.EXIF_TAG_BRIGHTNESS_VALUE);
printTagValue(jpegMetadata,
GpsTagConstants.GPS_TAG_GPS_LATITUDE_REF);
printTagValue(jpegMetadata, GpsTagConstants.GPS_TAG_GPS_LATITUDE);
printTagValue(jpegMetadata,
GpsTagConstants.GPS_TAG_GPS_LONGITUDE_REF);
printTagValue(jpegMetadata, GpsTagConstants.GPS_TAG_GPS_LONGITUDE);
System.out.println();
// simple interface to GPS data
final TiffImageMetadata exifMetadata = jpegMetadata.getExif();
if (null != exifMetadata) {
final TiffImageMetadata.GPSInfo gpsInfo = exifMetadata.getGPS();
if (null != gpsInfo) {
final String gpsDescription = gpsInfo.toString();
final double longitude = gpsInfo.getLongitudeAsDegreesEast();
final double latitude = gpsInfo.getLatitudeAsDegreesNorth();
System.out.println(" " + "GPS Description: "
+ gpsDescription);
System.out.println(" "
+ "GPS Longitude (Degrees East): " + longitude);
System.out.println(" "
+ "GPS Latitude (Degrees North): " + latitude);
}
}
// more specific example of how to manually access GPS values
final TiffField gpsLatitudeRefField = jpegMetadata
.findEXIFValueWithExactMatch(GpsTagConstants.GPS_TAG_GPS_LATITUDE_REF);
final TiffField gpsLatitudeField = jpegMetadata
.findEXIFValueWithExactMatch(GpsTagConstants.GPS_TAG_GPS_LATITUDE);
final TiffField gpsLongitudeRefField = jpegMetadata
.findEXIFValueWithExactMatch(GpsTagConstants.GPS_TAG_GPS_LONGITUDE_REF);
final TiffField gpsLongitudeField = jpegMetadata
.findEXIFValueWithExactMatch(GpsTagConstants.GPS_TAG_GPS_LONGITUDE);
if (gpsLatitudeRefField != null && gpsLatitudeField != null
&& gpsLongitudeRefField != null
&& gpsLongitudeField != null) {
// all of these values are strings.
final String gpsLatitudeRef = (String) gpsLatitudeRefField.getValue();
final RationalNumber gpsLatitude[] = (RationalNumber[]) (gpsLatitudeField
.getValue());
final String gpsLongitudeRef = (String) gpsLongitudeRefField
.getValue();
final RationalNumber gpsLongitude[] = (RationalNumber[]) gpsLongitudeField
.getValue();
final RationalNumber gpsLatitudeDegrees = gpsLatitude[0];
final RationalNumber gpsLatitudeMinutes = gpsLatitude[1];
final RationalNumber gpsLatitudeSeconds = gpsLatitude[2];
final RationalNumber gpsLongitudeDegrees = gpsLongitude[0];
final RationalNumber gpsLongitudeMinutes = gpsLongitude[1];
final RationalNumber gpsLongitudeSeconds = gpsLongitude[2];
// This will format the gps info like so:
//
// gpsLatitude: 8 degrees, 40 minutes, 42.2 seconds S
// gpsLongitude: 115 degrees, 26 minutes, 21.8 seconds E
System.out.println(" " + "GPS Latitude: "
+ gpsLatitudeDegrees.toDisplayString() + " degrees, "
+ gpsLatitudeMinutes.toDisplayString() + " minutes, "
+ gpsLatitudeSeconds.toDisplayString() + " seconds "
+ gpsLatitudeRef);
System.out.println(" " + "GPS Longitude: "
+ gpsLongitudeDegrees.toDisplayString() + " degrees, "
+ gpsLongitudeMinutes.toDisplayString() + " minutes, "
+ gpsLongitudeSeconds.toDisplayString() + " seconds "
+ gpsLongitudeRef);
}
System.out.println();
final List<ImageMetadataItem> items = jpegMetadata.getItems();
for (int i = 0; i < items.size(); i++) {
final ImageMetadataItem item = items.get(i);
System.out.println(" " + "item: " + item);
}
System.out.println();
}
}
private static void printTagValue(final JpegImageMetadata jpegMetadata,
final TagInfo tagInfo) {
final TiffField field = jpegMetadata.findEXIFValueWithExactMatch(tagInfo);
if (field == null) {
System.out.println(tagInfo.name + ": " + "Not Found.");
} else {
System.out.println(tagInfo.name + ": "
+ field.getValueDescription());
}
}
}
