java中的图片按比例缩放功能

1. 按固定长宽进行缩放

     /*      * 图片缩放,w，h为缩放的目标宽度和高度      * src为源文件目录，dest为缩放后保存目录      */     public static void zoomImage(String src,String dest,int w,int h) throws Exception {                  double wr=@H_304_37@0,hr=0;         File srCFile = new File(src);         File destFile = new File(dest);          BufferedImage bufimg = ImageiO.read(srcFile); //读取图片         Image ITemp = bufImg.getScaledInstance(w, h, bufImg.SCALE_SMOOTH);//设置缩放目标图片模板                  wr=w*1.0/bufImg.getWidth();     //获取缩放比例         hr=h*1.0 / bufImg.getHeight();          AffinetransformOp ato = new AffineTransformOp(AffineTransform.getScaleInstance(wr, hr), null);         Itemp = ato.filter(bufImg, null);         try {             ImageIO.write((BufferedImage) Itemp,dest.substring(dest.lastIndexOf(".")+1), destFile); //写入缩减后的图片         } catch (Exception ex) {             ex.PRintStackTrace();         }     } 

2. 按固定文件大小进行缩放

     /*    * 图片按比率缩放    * size为文件大小    */   public static void zoomImage(String src,String dest,Integer size) throws Exception {       File srcFile = new File(src);       File destFile = new File(dest);              long fileSize = srcFile.length();       if(fileSize < size * 1024)   //文件大于size k时，才进行缩放           return;              Double rate = (size * 1024 * 0.5) / fileSize; // 获取长宽缩放比例              BufferedImage bufImg = ImageIO.read(srcFile);       Image Itemp = bufImg.getScaledInstance(bufImg.getWidth(), bufImg.getHeight(), bufImg.SCALE_SMOOTH);                  AffineTransformOp ato = new AffineTransformOp(AffineTransform.getScaleInstance(rate, rate), null);       Itemp = ato.filter(bufImg, null);       try {           ImageIO.write((BufferedImage) Itemp,dest.substring(dest.lastIndexOf(".")+1), destFile);       } catch (Exception ex) {           ex.printStackTrace();       }