How do use use Picasso library while downloading images from Amazon S3?

问题

I am storing my images on Amazon S3. I use the following code to download image from Amazon S3

 S3ObjectInputStream content = s3Client.getObject("bucketname", url).getObjectContent();
                byte[] bytes ;
                bytes = IOUtils.toByteArray(content);
                bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
                bitmap = Bitmap.createScaledBitmap(bitmap, width, height, true);
                bitmap = CommonUtilities.getRoundedCornerBitmap(bitmap, 30);
                cache.put(url, new SoftReference<Bitmap>(bitmap));
                return bitmap;

While going through Picasso documentation, I read that to load images we simply need to do

Picasso.with(context).load("http://i.imgur.com/DvpvklR.png").into(imageView);

So how to download Amazon S3 images through Picasso.

回答1:

You can use AmazonS3.generatePresignedUrl(String, String, Date) to generate a presigned url and pass it to Picasso. Here is an example "Generate a Pre-signed Object URL using AWS SDK for Java". Though the example is for the Java SDK, it's applicable for the AWS Android SDK.

回答2:

You are getting the InputStream of the S3Object, which will give bytes representation of that object. Instead, you need to build URI from to the S3Object. As far as I know the url is build in following manner:

S3_END_POINT + bucket + key.

Check the use of S3Object redirect location (S3 gives different endpoint url, depending on your location)

Therefore:

String S3_END_POINT = "https://s3.amazonaws.com/"; // public files
S3Object s3Object = s3Client.getObject("bucketname", url);
String url = S3_END_POINT + s3Object.getBucketName() + SLASH + s3Object.getKey();
Picasso.with(context).load(url).into(imageView);

来源：https://stackoverflow.com/questions/30963995/how-do-use-use-picasso-library-while-downloading-images-from-amazon-s3

标签

android

amazon-web-services

amazon-s3

picasso