创建图片的缩略图

2022-06-05 00:20 204阅读 0赞

private void createThumbnail(String filename, int thumbWidth, int thumbHeight, int quality, String outFilename)
                throws InterruptedException, FileNotFoundException, IOException
        {
    // load image from filename
            Image image = Toolkit.getDefaultToolkit().getImage(filename);
            MediaTracker mediaTracker = new MediaTracker(new Container());
            mediaTracker.addImage(image, 0);
            mediaTracker.waitForID(0);
    // use this to test for errors at this point: System.out.println(mediaTracker.isErrorAny());
    // determine thumbnail size from WIDTH and HEIGHT
            double thumbRatio = (double)thumbWidth / (double)thumbHeight;
            int imageWidth = image.getWidth(null);
            int imageHeight = image.getHeight(null);
            double imageRatio = (double)imageWidth / (double)imageHeight;
            if (thumbRatio < imageRatio) {
                thumbHeight = (int)(thumbWidth / imageRatio);
            } else {
                thumbWidth = (int)(thumbHeight * imageRatio);
            }
    // draw original image to thumbnail image object and
    // scale it to the new size on-the-fly
            BufferedImage thumbImage = new BufferedImage(thumbWidth, thumbHeight, BufferedImage.TYPE_INT_RGB);
            Graphics2D graphics2D = thumbImage.createGraphics();
            graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
            graphics2D.drawImage(image, 0, 0, thumbWidth, thumbHeight, null);
    // save thumbnail image to outFilename
            BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(outFilename));
            JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
            JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(thumbImage);
            quality = Math.max(0, Math.min(quality, 100));
            param.setQuality((float)quality / 100.0f, false);
            encoder.setJPEGEncodeParam(param);
            encoder.encode(thumbImage);
            out.close();
        }