Reputation: 11
Context
I believe I have searched enough about this topic but haven't found an answer yet. If any of you have any answer please help out.
I am trying to send an image as an output to a service call from an android app
.
I have used BufferedImage
, ImageIO
and a ByteArrayOutputStream
to convert the image to a Base64 encoded string
(from many of the examples I could find on stackoverflow).
This Base64 encoded string
is received by the android app. Now, this needs to be converted back to an image and shown on an activity.
FYI. The image I am trying to send over is a QR code generated using zxing libraries.
Problem
This is where I am struggling. I am not sure how to do it. I haven't posted any sample code, since the server side code is pretty self explanatory and I don't yet have any code on the server side.
Sample code on the Android side
private Bitmap getBitmap() {
String base64String="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";
ByteArrayInputStream imageArr=new ByteArrayInputStream(Base64.decode(base64String, Base64.DEFAULT));
Bitmap bitmap = BitmapFactory.decodeStream(imageArr);
return bitmap;
}
Upvotes: 0
Views: 1944
Reputation: 11
@haraldK, thanks for giving me the right pointer. I was also wondering why I didn't see any padding, but didn't put enough focus on it to understand the issue. But, based on your hint, I finally figured out the issue. The issue was that I was not closing the OutputStream given by Base64 Encoder properly. In my code I had a the Base64 encoder stream as a wrapper of a ByteArrayOutputStream as below:
final ByteArrayOutputStream os = new ByteArrayOutputStream();
String qString = "";
try {
MatrixToImageWriter.writeToStream(matrix, formatName, Base64.getEncoder().wrap(os));
qString = os.toString("UTF-8");
os.close();
return qString;
} catch (final IOException ioe) {
throw new UncheckedIOException(ioe);
}
In the above code, I was closing the ByteArrayOutputStream using os.close() which was not required. But what was required was closing of the OutputStream given out by the Base64 encoder. I changed the code as below to make it work:
final ByteArrayOutputStream os = new ByteArrayOutputStream();
OutputStream base64Stream = Base64.getEncoder().wrap(os);
String qString = "";
try {
MatrixToImageWriter.writeToStream(matrix, formatName, base64Stream);
base64Stream.close();
qString = os.toString("UTF-8");
os.close();
return qString;
} catch (final IOException ioe) {
throw new UncheckedIOException(ioe);
}
After the above change, the base64 encoded strings are properly padded and are properly getting decoded on the Android side. On the android side this is code I have to display the image:
byte[] imageArr=Base64.decode(base64String.getBytes(), Base64.NO_WRAP);
Bitmap bitmap=BitmapFactory.decodeByteArray(imageArr, 0, imageArr.length);
return bitmap;
I didn't know how to upvote your answer, so I have created this as a separate answer. Thanks for your help.
Upvotes: 1
Reputation: 663
Can you please add your image Response string
As you are doing it in ByteArrayOutputStream you may missed the below item before decoding
String imageDataBytes = responseImageData.substring(responseImageData.indexOf(",")+1);
InputStream stream = new ByteArrayInputStream(Base64.decode(imageDataBytes.getBytes(), Base64.DEFAULT));
Bitmap bitmap = BitmapFactory.decodeStream(stream);
A good answer available for the same question here
Upvotes: 0