JAVA功能代码《8》----Java创建图片的缩略图

8.Java创建图片的缩略图

public 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();
	}