java图片压缩，,/** * 改变图

java图片压缩，,/** * 改变图

/**    * 改变图片的大小到宽为size，然后高随着宽等比例变化    * @param is 上传的图片的输入流    * @param os 改变了图片的大小后，把图片的流输出到目标OutputStream    * @param size 新图片的宽    * @param format 新图片的格式    * @throws IOException    */   public static void resizeImage1(InputStream is, OutputStream os, int size, String format) {        try {    BufferedImage prevImage = ImageIO.read(is);       double width = prevImage.getWidth();       double height = prevImage.getHeight();       double percent = size/width;       int newWidth = (int)(width * percent);       int newHeight = (int)(height * percent);       BufferedImage image = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_BGR);       //以下代码在压缩图片透明背景会变成变黑色    /* Graphics graphics = image.createGraphics();       graphics.drawImage(prevImage, 0, 0, newWidth, newHeight, null);       ImageIO.write(image, format, os);*/       /////////////////////////////////////////     //以下代码解决在压缩png格式的图片透明背景会变成变黑色的问题     Graphics2D g2d = image.createGraphics();      image = g2d.getDeviceConfiguration().createCompatibleImage(newWidth,newHeight,Transparency.TRANSLUCENT);         g2d.dispose();         g2d = image.createGraphics();         Image from = prevImage.getScaledInstance(newWidth, newHeight, prevImage.SCALE_AREA_AVERAGING);         g2d.drawImage(from, 0, 0, null);        g2d.dispose();         ImageIO.write(image, format,os);      os.flush();       is.close();       os.close();     } catch (Exception e) {    // TODO Auto-generated catch block    e.printStackTrace();   }    }