java中的图片按比例缩放功能
jopen
8年前
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(); } } 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(); }