How to write exif data to image in Android?

问题:

I'm trying to write a User_Comment and TAG_GPS to a captured image in an Android application using the exif interface, but for some reason the tags don't seem to be appended to the image when I view the image's details in the gallery.

It seems that maybe the tags are not being written to the captured image as the file path may be wrong. I think it could be because I've written the tags to an incorrect image path.

Does anyone know if their is a problem with the way I'm writing the tags to the image?

This is the code that saves the exif data following @Charlie's changes below:

private File getOutputPhotoFile() throws IOException {
          File directory = new File(Environment.getExternalStoragePublicDirectory(
                        Environment.DIRECTORY_PICTURES), getPackageName());
          if (!directory.exists()) {
            if (!directory.mkdirs()) {
              Log.e(TAG, "Failed to create storage directory.");
              return null;
            }
          }


          String timeStamp = new SimpleDateFormat("yyyMMdd_HHmmss", Locale.ENGLISH).format(new Date());

          File[] files = directory.listFiles();

          File exifVar =  new File(directory.getPath(), "IMG_" + timeStamp + ".jpg");
          if(files.length!=0) {
              File newestFile = files[files.length-1];
              exifVar =  new File(directory.getPath() + File.separator + newestFile.getName());
          }

          String mString = "Generic Text..";     
          ExifInterface exif = new ExifInterface(exifVar.getAbsolutePath());
          exif.setAttribute("UserComment", mString);
          exif.saveAttributes();


          exif.setAttribute(ExifInterface.TAG_GPS_LATITUDE,
            String.valueOf(latituteField.toString()));

          exif.setAttribute(ExifInterface.TAG_GPS_LONGITUDE, 
            String.valueOf(longitudeField.toString()));

          exif.saveAttributes();

          return exifVar; 




    }

回答1:

You need first to copy the exif files located here google exif to your project, then use the following code :

    ExifInterface exif = new ExifInterface();
    exif.readExif(exifVar.getAbsolutePath());
    exif.setTagValue(ExifInterface.TAG_USER_COMMENT, mString);
    exif.forceRewriteExif(exifVar.getAbsolutePath())); 

ExifInterface used here is the new one you've just added.

回答2:

You're using exifVar.toString(). This returns just the filename, not the path to the image. As your app is probably not in the folder with pictures, you should use exifVar.getAbsolutePath().

If you're not taking the picture at the same time you're running the program, the Path won't be right. Use this code instead:

File[] files = directory.listFiles();

if(files.length==0) {
    // No images available
    return;
}

File newestFile = files[files.length-1];

File exifVar =  new File(directory.getPath() + File.separator + newestFile.getName());

Off-Topic:

According to your huge import list:

import android.content.*;

imports

android.content.Context,
android.content.DialogInterface and
android.content.Intent

That makes your code quite a bit shorter. Just saying