publicstaticvoid zoom() {//目标图片
	File input = new File("D:/cnjbb_banner.jpg");
	//输出的位置
	String output = "D:/work_test/photo/jpeg/";
	try{
		InputStream imageStream = new FileInputStream(input);
		//根据目标图片建立一个缓存图片
		JPEGImageDecoder decoderFile = JPEGCodec.createJPEGDecoder(imageStream);
		BufferedImage imageFile = decoderFile.decodeAsBufferedImage();
		float zoom = 0.5F;//你要方缩的比例
		//获得目标图片的宽高，同时乘以放缩比例得到新图片大小
		int w = (int) (imageFile.getWidth() * zoom);
		int h = (int) (imageFile.getHeight() * zoom);
		//建立一个新图片的缓存图片
		BufferedImage bufImage = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
		FileOutputStream out = new FileOutputStream(output + input.getName());
		//从目标图片上获得Graphics以便画在新图片上，最后一个参数是内部无名类，可以用null代替
		Graphics g = bufImage.getGraphics();
		g.drawImage(imageFile, 0, 0, w, h, new ImageObserver() {
		 public boolean imageUpdate(
		 	Image img, int infoflags, int x, int y, int width, int height) {
		  return true;
    		}
		});
		//编码输出
		JPEGImageEncoder jpeg = JPEGCodec.createJPEGEncoder(out);
		jpeg.encode(bufImage);
		out.flush();
			out.close();
		imageStream.close();
	} catch (Exception e) {
		e.printStackTrace();
	}
}