public String handleRequest()

in sample-apps/s3-java/src/main/java/example/Handler.java [44:128]
65 lines of code
8 McCabe index (conditional complexity)

  public String handleRequest(S3Event s3event, Context context) {
    try {
      logger.info("EVENT: " + gson.toJson(s3event));
      S3EventNotificationRecord record = s3event.getRecords().get(0);
      
      String srcBucket = record.getS3().getBucket().getName();

      // Object key may have spaces or unicode non-ASCII characters.
      String srcKey = record.getS3().getObject().getUrlDecodedKey();

      String dstBucket = srcBucket;
      String dstKey = "resized-" + srcKey;

      // Infer the image type.
      Matcher matcher = Pattern.compile(".*\\.([^\\.]*)").matcher(srcKey);
      if (!matcher.matches()) {
          logger.info("Unable to infer image type for key " + srcKey);
          return "";
      }
      String imageType = matcher.group(1);
      if (!(JPG_TYPE.equals(imageType)) && !(PNG_TYPE.equals(imageType))) {
          logger.info("Skipping non-image " + srcKey);
          return "";
      }

      // Download the image from S3 into a stream
      AmazonS3 s3Client = AmazonS3ClientBuilder.defaultClient();
      S3Object s3Object = s3Client.getObject(new GetObjectRequest(
              srcBucket, srcKey));
      InputStream objectData = s3Object.getObjectContent();

      // Read the source image
      BufferedImage srcImage = ImageIO.read(objectData);
      int srcHeight = srcImage.getHeight();
      int srcWidth = srcImage.getWidth();
      // Infer the scaling factor to avoid stretching the image
      // unnaturally
      float scalingFactor = Math.min(MAX_WIDTH / srcWidth, MAX_HEIGHT
              / srcHeight);
      int width = (int) (scalingFactor * srcWidth);
      int height = (int) (scalingFactor * srcHeight);

      BufferedImage resizedImage = new BufferedImage(width, height,
              BufferedImage.TYPE_INT_RGB);
      Graphics2D g = resizedImage.createGraphics();
      // Fill with white before applying semi-transparent (alpha) images
      g.setPaint(Color.white);
      g.fillRect(0, 0, width, height);
      // Simple bilinear resize
      g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
              RenderingHints.VALUE_INTERPOLATION_BILINEAR);
      g.drawImage(srcImage, 0, 0, width, height, null);
      g.dispose();

      // Re-encode image to target format
      ByteArrayOutputStream os = new ByteArrayOutputStream();
      ImageIO.write(resizedImage, imageType, os);
      InputStream is = new ByteArrayInputStream(os.toByteArray());
      // Set Content-Length and Content-Type
      ObjectMetadata meta = new ObjectMetadata();
      meta.setContentLength(os.size());
      if (JPG_TYPE.equals(imageType)) {
          meta.setContentType(JPG_MIME);
      }
      if (PNG_TYPE.equals(imageType)) {
          meta.setContentType(PNG_MIME);
      }

      // Uploading to S3 destination bucket
      logger.info("Writing to: " + dstBucket + "/" + dstKey);
      try {
        s3Client.putObject(dstBucket, dstKey, is, meta);
      }
      catch(AmazonServiceException e)
      {
        logger.error(e.getErrorMessage());
        System.exit(1);
      }
      logger.info("Successfully resized " + srcBucket + "/"
              + srcKey + " and uploaded to " + dstBucket + "/" + dstKey);
      return "Ok";
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
  }