今天遇到了二维码生成的图片需要切掉白边的情况，查看之前的二维码生成代码，发现有这么一行

hints.put(EncodeHintType.MARGIN, 1);

感觉应该是设置边距的意思，果断改成

hints.put(EncodeHintType.MARGIN, 0);

发现其实并不能去掉白边。

于是百度找到方案：

private static BufferedImage getNormalQRCode(String content) throws WriterException {Hashtable<EncodeHintType, Object> hints = new Hashtable<EncodeHintType, Object>();hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H);hints.put(EncodeHintType.CHARACTER_SET, CHARSET);hints.put(EncodeHintType.MARGIN, 1);BitMatrix bitMatrix = new MultiFormatWriter().encode(content,BarcodeFormat.QR_CODE, QRCODE_SIZE, QRCODE_SIZE, hints);//调用去除白边方法bitMatrix = deleteWhite(bitMatrix);int width = bitMatrix.getWidth();int height = bitMatrix.getHeight();BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);for (int x = 0; x < width; x++) {for (int y = 0; y < height; y++) {image.setRGB(x, y, bitMatrix.get(x, y) ? BLACK //int 0: WHITE //int 255);}}return image;}
ImageIO.write(image, "jpg", response.getOutputStream());  private static BitMatrix deleteWhite(BitMatrix matrix) {int[] rec = matrix.getEnclosingRectangle();int resWidth = rec[2] + 1;int resHeight = rec[3] + 1;BitMatrix resMatrix = new BitMatrix(resWidth, resHeight);resMatrix.clear();for (int i = 0; i < resWidth; i++) {for (int j = 0; j < resHeight; j++) {if (matrix.get(i + rec[0], j + rec[1]))resMatrix.set(i, j);}}return resMatrix;}

搞定

最近项目里需要生成一些二维码，使用之后发现一些问题，生成之后的图片，白色边框区域太大了，导致二维码内容区域太小。 
百度了一下，有人说设置EncodeHintType.MARGIN属性即可，这个属性值为1-4，实际测试发现并没有什么卵用。（顺便说一下，一些比较老的版本中，这个EncodeHintType只有CHARACTER_SET和ERROR_CORRECTION两种属性设置，比较新的库才新增了其他属性，我这里使用的是3.0版本） 
后来找到另外一个解决办法：自己手动去除黑边，代码如下：public static Bitmap Create2DCode(String str, int width, int height) {try {Hashtable<EncodeHintType, Object> hints = new Hashtable<EncodeHintType, Object>();hints.put(EncodeHintType.CHARACTER_SET, "utf-8");hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H);hints.put(EncodeHintType.MARGIN, 1);BitMatrix matrix = new QRCodeWriter().encode(str, BarcodeFormat.QR_CODE, width, height);matrix = deleteWhite(matrix);//删除白边width = matrix.getWidth();height = matrix.getHeight();int[] pixels = new int[width * height];for (int y = 0; y < height; y++) {for (int x = 0; x < width; x++) {if (matrix.get(x, y)) {pixels[y * width + x] = Color.BLACK;} else {pixels[y * width + x] = Color.WHITE;}}}Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);bitmap.setPixels(pixels, 0, width, 0, 0, width, height);return bitmap;} catch (Exception e) {return null;}}private static BitMatrix deleteWhite(BitMatrix matrix) {int[] rec = matrix.getEnclosingRectangle();int resWidth = rec[2] + 1;int resHeight = rec[3] + 1;BitMatrix resMatrix = new BitMatrix(resWidth, resHeight);resMatrix.clear();for (int i = 0; i < resWidth; i++) {for (int j = 0; j < resHeight; j++) {if (matrix.get(i + rec[0], j + rec[1]))resMatrix.set(i, j);}}return resMatrix;}