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=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();
- }
- }
-
- /*
- * 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();
- }
来自： http://segmentfault.com/a/1190000004253565 | 
