Question

我使用Camera 2 API，我需要获取图像元数据（完全是ISO）才能将图像保存在设备上。

此时我正在使用ExifInterface，但此类的构造函数仅获取File或从api24 InputStream开始。

如何在保存之前从图像中获取ISO？

修改

private final ImageReader.OnImageAvailableListener mOnImageAvailableListener
        = new ImageReader.OnImageAvailableListener() {

    @Override
    public void onImageAvailable(final ImageReader reader) {

        new AsyncTask<Void, Void, Void>() {

            @Override
            protected Void doInBackground(Void... voids) {
                new ImageSaver(context, reader.acquireNextImage()).writeImageToStorage();
                return null;
            }
        }
    }
};

public final class ImageSaver {
private Context context;
private static File imageFile;
private final Image image;

public ImageSaver(Context context, Image image) {
    this.context = context;
    this.image = image;
    imageFile = getImageFile(UtilClass.getAvatarPhotosDirFile(context));
}

private File getImageFile(File path) {
    return new File(path.getPath() + File.separator + getStamp() + ".jpeg");
}

public void writeImageToStorage() {
    final ByteBuffer buffer = getByteBuffer();
    final byte[] bytes = getBytes(buffer);
    writeFile(imageFile, bytes);
}

@Nullable
private ByteBuffer getByteBuffer() {
    ByteBuffer buffer = null;
    if (image != null) {
        buffer = image.getPlanes()[0].getBuffer();
    }
    return buffer;
}

private byte[] getBytes(ByteBuffer buffer) {
    byte[] bytes = new byte[0];
    if (buffer != null) {
        bytes = new byte[buffer.remaining()];
    }
    if (buffer != null) {
        buffer.get(bytes);
    }
    return bytes;
}

private void writeFile(File file, byte[] bytes) {
    BufferedOutputStream bos = null;

    try {
        bos = new BufferedOutputStream(new FileOutputStream(file));
        bos.write(bytes);
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (image != null) {
            image.close();
        }
        if (null != bos) {
            try {
                bos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

@NonNull
private String getStamp() {

    final int pictureAmount = PreferencesHelper.getIntShared(context, States.PICTURE_AMOUNT) + 1;
    String stamp;

    switch (pictureAmount){
        case 1:
            stamp = "pose1";
            break;
        case 2:
            stamp = "pose3";
            break;
        case 3:
            stamp = "pose5";
            break;
        case 4:
            stamp = "pose7";
            break;
        default:
            stamp = "BG";
            break;
    }
    return stamp;
}

public static String getImageFilePath() {
    return imageFile.getPath();
}

}

Answer 1

ByteArrayinputStream bais = new ByteArrayInputStream(bytes);

bytes包含jpeg。

将bais用作InputStream用于Android 7.0的新ExifInterface。

否则使用不同的Exifinterface类。不止一个。

如何在保存图像之前获取元数据？

1 个答案: