java创建缩略图

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();

}