图片缩放
/** * 通过传进来的二进制图片流，将图片缩放后返回，用于文件上传取得缩放图，然后存数据库 ** @param bt * 原图二进制 * @param targetW * 目标宽度 * @param targetH * 目标长度 * @return 缩放后图片的二进制 * @throws IOException * 流读写异常 */public static byte[] resize(byte[] bt, Integer targetW, Integer targetH)throws IOException {ByteArrayInputStream bai = new java.io.ByteArrayInputStream(bt);BufferedImage bimg = javax.imageio.ImageIO.read(bai);BufferedImage target = resize(bimg, targetW, targetH);ByteArrayOutputStream os = new ByteArrayOutputStream();JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(os);encoder.encode(target);byte[] arr = os.toByteArray();os.flush();os.close();bai.close();return arr;} 昨天做的一个图片缩放，能够将上传的文件进行缩放后返回字节数组，然后存放数据库或其它操作。public static BufferedImage resize(BufferedImage source, int targetW,int targetH) throws IOException {// targetW，targetH分别表示目标长和宽int type = source.getType();BufferedImage target = null;double sx = (double) targetW / source.getWidth();double sy = (double) targetH / source.getHeight();// 这里想实现在targetW，targetH范围内实现等比缩放。如果不需要等比缩放// 则将下面的if else语句注释即可if (sx > sy) {sx = sy;targetW = (int) (sx * source.getWidth());} else {sy = sx;targetH = (int) (sy * source.getHeight());}if (type == BufferedImage.TYPE_CUSTOM) {ColorModel cm = source.getColorModel();WritableRaster raster = cm.createCompatibleWritableRaster(targetW,targetH);boolean alphaPremultiplied = cm.isAlphaPremultiplied();target = new BufferedImage(cm, raster, alphaPremultiplied, null);} elsetarget = new BufferedImage(targetW, targetH, type);Graphics2D g = target.createGraphics();g.setRenderingHint(RenderingHints.KEY_RENDERING,RenderingHints.VALUE_RENDER_QUALITY);g.drawRenderedImage(source, AffineTransform.getScaleInstance(sx, sy));g.dispose();return target;}
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