内容目录
EXIF代表“可交换图像文件格式”。这种类型的信息是根据TIFF规范格式化的，可以在JPG，TIFF，PNG，JP2，PGF，MIFF，HDP，PSP和XCF图像以及许多基于TIFF的RAW图像，甚至某些AVI中找到和MOV视频。
比如随便打开一张图片，可以看到这张图片的很多信息：
读取EXIF信息
metadata-extractor 是一个开源的，经过广泛验证并且被很多大企业（如Apache，IBM等）使用的一个库，有 Java 和 .Net 两种语言。这里我们演示 Java 语言。代码都很简单，这里是 GitHub地址，添加依赖什么的我就不再说了。
package com.smile.test;
import com.drew.imaging.ImageMetadataReader;
import com.drew.imaging.ImageProcessingException;
import com.drew.metadata.Directory;
import com.drew.metadata.Metadata;
import com.drew.metadata.Tag;
import com.drew.metadata.exif.ExifSubIFDDirectory;
import org.juniTestExift.jupiter.api.Test;
import java.io.File;
import java.io.IOException;
import java.util.Date;
public class TestExif {
@Test
public void viewExif() throws ImageProcessingException, IOException {
final String jpegPath = "/Users/smile/Desktop/demo.jpg";
File jpegFile = new File(jpegPath);
Metadata metadata = ImageMetadataReader.readMetadata(jpegFile);
// 打印所有Tag
for (Directory directory : metadata.getDirectories()) {
for (Tag tag : directory.getTags()) {
System.out.println(tag);
}
}
// obtain the Exif directory
ExifSubIFDDirectory directory = metadata.getFirstDirectoryOfType(ExifSubIFDDirectory.class);
// 查询特定Tag：拍摄日期（OS X上叫内容创建时间）
Date date = directory.getDate(ExifSubIFDDirectory.TAG_DATETIME_ORIGINAL);
}
}他的输出可能是这样的（不完整）：
[JPEG] Compression Type - Baseline
[JPEG] Data Precision - 8 bits
[JPEG] Image Height - 3619 pixels
[JPEG] Image Width - 2714 pixels
[JPEG] Number of Components - 3
[JPEG] Component 1 - Y component: Quantization table 0, Sampling factors 1 horiz/1 vert
[JPEG] Component 2 - Cb component: Quantization table 1, Sampling factors 1 horiz/1 vert
[JPEG] Component 3 - Cr component: Quantization table 1, Sampling factors 1 horiz/1 vert
[Exif IFD0] Image Width - 3024 pixels
[Exif IFD0] Image Height - 4032 pixels
[Exif IFD0] Bits Per Sample - 8 8 8 bits/component/pixel
[Exif IFD0] Photometric Interpretation - RGB
[Exif IFD0] Make - Apple
[Exif IFD0] Model - iPhone XS Max
[Exif IFD0] Orientation - Top, left side (Horizontal / normal)
[Exif IFD0] Samples Per Pixel - 3 samples/pixel
[Exif IFD0] X Resolution - 72 dots per inch
[Exif IFD0] Y Resolution - 72 dots per inch
[Exif IFD0] Resolution Unit - Inch
[Exif IFD0] Software - Adobe Photoshop CS6 (Windows)
[Exif IFD0] Date/Time - 2019:11:26 10:42:47上面这些信息可能都没啥用，下面我们就演示输出上面第一张图中的信息：
EXIF信息查询
EXIF的信息是用tag来标记的：GitHub上列出了常用的标签，完整的标签列表在这里。
package com.smile.test;
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;
import com.drew.metadata.exif.ExifIFD0Directory;
import com.drew.metadata.exif.ExifSubIFDDirectory;
import com.drew.metadata.exif.ExifThumbnailDirectory;
import com.drew.metadata.file.FileSystemDirectory;
import com.drew.metadata.jpeg.*;
import org.junit.jupiter.api.Test;
import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimeZone;
public class TestExif {
@Test
public void queryExif() throws ImageProcessingException, IOException, MetadataException {
final String jpegPath = "/Users/smile/Desktop/demo.jpg";
File jpegFile = new File(jpegPath);
Metadata metadata = ImageMetadataReader.readMetadata(jpegFile);
// obtain the Exif directory
ExifSubIFDDirectory exifSubIFDDirectory = metadata.getFirstDirectoryOfType(ExifSubIFDDirectory.class);
ExifIFD0Directory exifIFD0Directory = metadata.getFirstDirectoryOfType(ExifIFD0Directory.class);
FileSystemDirectory fileSystemDirectory = metadata.getFirstDirectoryOfType(FileSystemDirectory.class);
ExifThumbnailDirectory exifThumbnailDirectory = metadata.getFirstDirectoryOfType(ExifThumbnailDirectory.class);
JpegDirectory jpegDirectory = metadata.getFirstDirectoryOfType(JpegDirectory.class);
print("创建时间", exifIFD0Directory.getDate(ExifIFD0Directory.TAG_DATETIME, TimeZone.getDefault()));
print("修改时间", fileSystemDirectory.getDate(FileSystemDirectory.TAG_FILE_MODIFIED_DATE, TimeZone.getDefault()));
print("内容创建时间", exifSubIFDDirectory.getDate(ExifSubIFDDirectory.TAG_DATETIME_ORIGINAL, TimeZone.getDefault()));
print("尺寸", jpegDirectory.getInt(JpegDirectory.TAG_IMAGE_WIDTH) + "x" + jpegDirectory.getInt(JpegDirectory.TAG_IMAGE_HEIGHT));
print("分辨率", exifThumbnailDirectory.getInt(ExifThumbnailDirectory.TAG_X_RESOLUTION) + "x" + exifThumbnailDirectory.getString(ExifThumbnailDirectory.TAG_Y_RESOLUTION));
print("色彩空间", exifSubIFDDirectory.getString(ExifSubIFDDirectory.TAG_COLOR_SPACE));
print("设备制造商", exifIFD0Directory.getString(ExifIFD0Directory.TAG_MAKE));
print("设备型号", exifIFD0Directory.getString(ExifIFD0Directory.TAG_MODEL));
print("镜头型号", exifSubIFDDirectory.getString(ExifSubIFDDirectory.TAG_LENS_MODEL));
print("光圈值", exifSubIFDDirectory.getDouble(ExifSubIFDDirectory.TAG_APERTURE));
print("曝光时间", exifSubIFDDirectory.getString(ExifSubIFDDirectory.TAG_EXPOSURE_TIME));
print("焦距", exifSubIFDDirectory.getString(ExifSubIFDDirectory.TAG_FOCAL_LENGTH) + "毫米");
print("ISO感光度", exifSubIFDDirectory.getString(ExifSubIFDDirectory.TAG_ISO_EQUIVALENT));
print("闪光灯", exifSubIFDDirectory.getString(ExifSubIFDDirectory.TAG_FLASH));
print("光圈数", "f/" + exifSubIFDDirectory.getString(ExifSubIFDDirectory.TAG_FNUMBER));
print("测光模式", exifSubIFDDirectory.getString(ExifSubIFDDirectory.TAG_METERING_MODE));
print("白平衡", exifSubIFDDirectory.getString(ExifSubIFDDirectory.TAG_WHITE_BALANCE_MODE));
print("内容创作者", exifIFD0Directory.getString(ExifIFD0Directory.TAG_SOFTWARE));
}
public void print(String tag, Object value) {
final SimpleDateFormat formatter = new SimpleDateFormat("yyyy年MM月dd日 a h:mm");
String v = "";
if (value != null) {
if (value instanceof Date) {
v = formatter.format(value);
} else {
v = value.toString();
}
}
System.out.println(String.format("%15s\t\t\t%s", tag, v));
}
}你的输出可能是这样的：
创建时间 2019年11月26日 上午 10:42
修改时间 2019年11月26日 上午 10:42
内容创建时间 2019年04月16日 下午 8:00
尺寸 2714x3619
分辨率 72x72
色彩空间 65535
设备制造商 Apple
设备型号 iPhone XS Max
镜头型号 iPhone XS Max back dual camera 4.25mm f/1.8
光圈值 1.6959938128383605
曝光时间 0.04
焦距 4.25毫米
ISO感光度 500
闪光灯 16
光圈数 f/1.8
测光模式 5
白平衡 0
内容创作者 Adobe Photoshop CS6 (Windows)
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