Android:上传图片而不会丢失Exif数据 [英] Android: Uploading image without losing Exif data
问题描述
在我们的应用程序中，使用(大致)以下代码的用户多年来已经上传了数百万个图像:
In our app users have been uploading millions of images for years using (roughly) this code:
BitmapFactory.Options bmOptions = new BitmapFactory.Options();
bmOptions.inJustDecodeBounds = true;
BitmapFactory.decodeFile(postFilePath, bmOptions);
Bitmap roughBitmap = BitmapFactory.decodeFile(postFilePath, bmOptions);
ByteArrayOutputStream stream = new ByteArrayOutputStream();
roughBitmap.compress(Bitmap.CompressFormat.JPEG, 70, stream);
InputStream fis = new ByteArrayInputStream(stream.toByteArray());
int fileSize = stream.toByteArray().length;
conn.setRequestProperty("Content-Length", Integer.toString(fileSize));
conn.setFixedLengthStreamingMode(fileSize);
...
if (fis != null) {
byte[] buf = new byte[10240];
int read;
while ((read = fis.read(buf)) > 0) {
os.write(buf, 0, read);
totalBytesRead += read;
if (uploadProgressListener != null) {
try {
uploadProgressListener.onBytesUploaded(read);
} catch (Exception e) {
Log.e(e);
}
}
}
fis.close();
}
最近，我们看到需要保留上传图像的Exif数据.问题在于，压缩位图时会丢失图像Exif数据.我想到了使用ExifInterface从原始文件中提取此数据:
Recently we saw the need to preserve the Exif data of uploaded images. The problem is that the image Exif data is lost when compressing the bitmap. I thought of using ExifInterface for extracting this data from the original file:
ExifInterface oldExif = new ExifInterface(postFilePath);
String value = oldExif.getAttribute(ExifInterface.TAG_DATETIME);
..，然后将其添加到InputStream fis，然后继续上传文件.问题是ExifInterface 无法将Exif数据保存到InputStream .
..and then adding it to the InputStream fis and then continue uploading the file. The problem is that ExifInterface cannot save Exif data to an InputStream.
Exif数据上传到服务器后如何保留在图像中?
How can Exif data be retained in the images when they'er uploaded to the server?
这不是重复的内容:
为了进一步说明，我尝试通过以下方法使用建议的duplicate question:
It's not a duplicate:
Just to clarify deeper, I've tried using the suggested duplicate question by using this method:
public static void copyExif(String originalPath, InputStream newStream) throws IOException {
String[] attributes = new String[]
{
ExifInterface.TAG_DATETIME,
ExifInterface.TAG_DATETIME_DIGITIZED,
ExifInterface.TAG_EXPOSURE_TIME,
ExifInterface.TAG_FLASH,
ExifInterface.TAG_FOCAL_LENGTH,
ExifInterface.TAG_GPS_ALTITUDE,
ExifInterface.TAG_GPS_ALTITUDE_REF,
ExifInterface.TAG_GPS_DATESTAMP,
ExifInterface.TAG_GPS_LATITUDE,
ExifInterface.TAG_GPS_LATITUDE_REF,
ExifInterface.TAG_GPS_LONGITUDE,
ExifInterface.TAG_GPS_LONGITUDE_REF,
ExifInterface.TAG_GPS_PROCESSING_METHOD,
ExifInterface.TAG_GPS_TIMESTAMP,
ExifInterface.TAG_MAKE,
ExifInterface.TAG_MODEL,
ExifInterface.TAG_ORIENTATION,
ExifInterface.TAG_SUBSEC_TIME,
ExifInterface.TAG_WHITE_BALANCE
};
ExifInterface oldExif = new ExifInterface(originalPath);
ExifInterface newExif = new ExifInterface(newStream);
if (attributes.length > 0) {
for (int i = 0; i < attributes.length; i++) {
String value = oldExif.getAttribute(attributes[i]);
if (value != null)
newExif.setAttribute(attributes[i], value);
}
newExif.saveAttributes();
}
}
..但在newExif.saveAttributes();之后却出现了异常java.io.IOException: ExifInterface does not support saving attributes for the current input.，因为我正在尝试将属性保存到InputStream.我还能怎么做?
.. but got the exception java.io.IOException: ExifInterface does not support saving attributes for the current input. after newExif.saveAttributes(); because I'm trying to save the attributes to an InputStream. How else can I do it?
推荐答案
我的解决方案:
按照 @amuttsch 和 @CommonsWare 的建议，我:
- 将缩放/压缩的位图保存到临时文件
- 将exif从原始文件复制到临时文件
- 将临时文件转换为字节数组，并将其发送上载
..然后我发现服务器在生成图像变体:-P时再次剥离了Exif，但这是服务器人员正在努力纠正的另一个故事.
.. then I found out that the server strips the Exif again while generating image variants :-P but that's another story which server guys are now working to correct.
主要代码:
...
// Copy original Exif to scaledBitmap
String tempFilePath = getTempFilePath(postFilePath);
try {
FileOutputStream out = new FileOutputStream(tempFilePath);
scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 70, out);
copyExif(postFilePath, tempFilePath);
} catch (Exception e) {
e.printStackTrace();
}
// Get stream from temp (exif loaded) file
File tempFile = new File(tempFilePath);
byte[] byteFile = readFile(tempFile);
fis = new ByteArrayInputStream(byteFile);
// Remove the temp file
boolean deleted = tempFile.delete();
// Finalize
int fileSize = byteFile.length;
conn.setRequestProperty("Content-Length", Integer.toString(fileSize));
conn.setFixedLengthStreamingMode(fileSize);
...
getTempFilePath():
private String getTempFilePath(String filename) {
String temp = "_temp";
int dot = filename.lastIndexOf(".");
String ext = filename.substring(dot + 1);
if (dot == -1 || !ext.matches("\\w+")) {
filename += temp;
} else {
filename = filename.substring(0, dot) + temp + "." + ext;
}
return filename;
}
copyExif():
public static void copyExif(String originalPath, String newPath) throws IOException {
String[] attributes = new String[]
{
ExifInterface.TAG_DATETIME,
ExifInterface.TAG_DATETIME_DIGITIZED,
ExifInterface.TAG_EXPOSURE_TIME,
ExifInterface.TAG_FLASH,
ExifInterface.TAG_FOCAL_LENGTH,
ExifInterface.TAG_GPS_ALTITUDE,
ExifInterface.TAG_GPS_ALTITUDE_REF,
ExifInterface.TAG_GPS_DATESTAMP,
ExifInterface.TAG_GPS_LATITUDE,
ExifInterface.TAG_GPS_LATITUDE_REF,
ExifInterface.TAG_GPS_LONGITUDE,
ExifInterface.TAG_GPS_LONGITUDE_REF,
ExifInterface.TAG_GPS_PROCESSING_METHOD,
ExifInterface.TAG_GPS_TIMESTAMP,
ExifInterface.TAG_MAKE,
ExifInterface.TAG_MODEL,
ExifInterface.TAG_ORIENTATION,
ExifInterface.TAG_SUBSEC_TIME,
ExifInterface.TAG_WHITE_BALANCE
};
ExifInterface oldExif = new ExifInterface(originalPath);
ExifInterface newExif = new ExifInterface(newPath);
if (attributes.length > 0) {
for (int i = 0; i < attributes.length; i++) {
String value = oldExif.getAttribute(attributes[i]);
if (value != null)
newExif.setAttribute(attributes[i], value);
}
newExif.saveAttributes();
}
}
readFile():
public static byte[] readFile(File file) throws IOException {
// Open file
RandomAccessFile f = new RandomAccessFile(file, "r");
try {
// Get and check length
long longlength = f.length();
int length = (int) longlength;
if (length != longlength)
throw new IOException("File size >= 2 GB");
// Read file and return data
byte[] data = new byte[length];
f.readFully(data);
return data;
} finally {
f.close();
}
}
这篇关于Android:上传图片而不会丢失Exif数据的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
