创建图片的缩略图 createThumbnail

  1. private void createThumbnail(String filename, int thumbWidth, int thumbHeight, int quality, String outFilename)
  2.         throws InterruptedException, FileNotFoundException, IOException
  3.     {
  4.         // load image from filename  
  5.         Image image = Toolkit.getDefaultToolkit().getImage(filename);
  6.         MediaTracker mediaTracker = new MediaTracker(new Container());
  7.         mediaTracker.addImage(image, 0);
  8.         mediaTracker.waitForID(0);
  9.         // use this to test for errors at this point: System.out.println(mediaTracker.isErrorAny());  
  10.         // determine thumbnail size from WIDTH and HEIGHT  
  11.         double thumbRatio = (double)thumbWidth / (double)thumbHeight;
  12.         int imageWidth = image.getWidth(null);
  13.         int imageHeight = image.getHeight(null);
  14.         double imageRatio = (double)imageWidth / (double)imageHeight;
  15.         if (thumbRatio < imageRatio) {
  16.             thumbHeight = (int)(thumbWidth / imageRatio);
  17.         } else {
  18.             thumbWidth = (int)(thumbHeight * imageRatio);
  19.         }
  20.         // draw original image to thumbnail image object and  
  21.         // scale it to the new size on-the-fly  
  22.         BufferedImage thumbImage = new BufferedImage(thumbWidth, thumbHeight, BufferedImage.TYPE_INT_RGB);
  23.         Graphics2D graphics2D = thumbImage.createGraphics();
  24.         graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
  25.         graphics2D.drawImage(image, 00, thumbWidth, thumbHeight, null);
  26.         // save thumbnail image to outFilename  
  27.         BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(outFilename));
  28.         JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
  29.         JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(thumbImage);
  30.         quality = Math.max(0, Math.min(quality, 100));
  31.         param.setQuality((float)quality / 100.0f, false);
  32.         encoder.setJPEGEncodeParam(param);
  33.         encoder.encode(thumbImage);
  34.         out.close();
  35.     }

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