Java二维码图片处理

写这个篇文章是为了记录一下使用Java操作二维码的一些套路。因为在做这件事的时候，是遇到了一些问题的，这里记录一下，以备不时之需。

需求

根据文字内容生成二维码，在二维码中间加入logo图片，最后将二维码嵌入外部背景图中，写入到指定路径

效果

测试代码：

String content = "这是二维码内容";
String logoPath = "F:/test/qrcode/logo.png";
String backImagePath = "F:/test/qrcode/backImage.jpg";
String outputPath = "F:/test/qrcode/result.jpg";
boolean result = QrCodeUtil.createAndSaveQrCodeImg(content, logoPath, backImagePath, outputPath);

效果：

maven依赖

<dependency><groupId>com.google.zxing</groupId><artifactId>core</artifactId><version>3.3.0</version>
</dependency>

源码

文字生成二维码

此处生成二维码图片，使用了自定义的encode方法和resizeAndCreateBufferedImage方法，相关源码和原因见下方的问题1

 /*** 生成二维码image** @param content 二维码内容* @return BufferedImage*/private static BufferedImage createQrCodeImage(String content) {return createQrCodeImage(content, 200, 200);}/*** 生成二维码image** @param content 二维码内容* @param width   宽度* @param height  长度* @return bufferImage*/private static BufferedImage createQrCodeImage(String content, int width, int height) {long start = System.currentTimeMillis();BufferedImage image = null;try {Hashtable<EncodeHintType, Object> hints = new Hashtable<>();hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H);hints.put(EncodeHintType.CHARACTER_SET, "utf-8");hints.put(EncodeHintType.MARGIN, 1);// 使用自定义的方法，解决白边问题BitMatrix bitMatrix = encode(content, BarcodeFormat.QR_CODE, width, height, hints);// 重新调整大小，满足输入宽高image = resizeAndCreateBufferedImage(bitMatrix, width, height);} catch (WriterException e) {logger.error("QRCodeUtil-createQrCodeImage 生成二维码异常:", e);}logger.info("QRCodeUtil-createQrCodeImage end. cost:{} ", (System.currentTimeMillis() - start));return image;}

读取图片信息

 /*** 从图片路径读取生成image** @param imagePath 图片文件地址* @return bufferedImage*/private static BufferedImage createBufferedImage(String imagePath) {long start = System.currentTimeMillis();BufferedImage bi = null;try {BufferedImage tmpImage = ImageIO.read(new File(imagePath));// 防止写入jpg时出现失真异常，这里new一个新的image包一下bi = new BufferedImage(tmpImage.getWidth(), tmpImage.getHeight(), BufferedImage.TYPE_INT_RGB);bi.getGraphics().drawImage(tmpImage, 0, 0, null);} catch (IOException e) {logger.error("读取文件{} 生成bufferedImage失败:", imagePath, e);}logger.info("QRCodeUtil-createBufferedImage end. cost:{}", System.currentTimeMillis() - start);return bi;}

二维码中间填充logo图片

 /*** 二维码中间插入logo** @param codeImage 二维码image* @param logoImage logo image* @return 插入结果*/private static boolean combineCodeAndInnerLogo(BufferedImage codeImage, BufferedImage logoImage) {return combineCodeAndInnerLogo(codeImage, logoImage, true);}/*** 二维码中间插入logo** @param codeImage    二维码image* @param logoImage    logo image* @param needCompress 是否需要压缩* @return 插入结果*/private static boolean combineCodeAndInnerLogo(BufferedImage codeImage, Image logoImage, boolean needCompress) {boolean result;try {int logoWidth = logoImage.getWidth(null);int logoHeight = logoImage.getHeight(null);// 如果设置了需要压缩，则进行压缩if (needCompress) {logoWidth = logoWidth > LOGO_MAX_HEIGHT ? LOGO_MAX_WIDTH : logoWidth;logoHeight = logoHeight > LOGO_MAX_HEIGHT ? LOGO_MAX_HEIGHT : logoHeight;Image image = logoImage.getScaledInstance(logoWidth, logoHeight, Image.SCALE_SMOOTH);BufferedImage tag = new BufferedImage(logoWidth, logoHeight, BufferedImage.TYPE_INT_RGB);Graphics gMaker = tag.getGraphics();// 绘制缩小后的图gMaker.drawImage(image, 0, 0, null);gMaker.dispose();logoImage = image;}// 在中心位置插入logoGraphics2D codeImageGraphics = codeImage.createGraphics();int codeWidth = codeImage.getWidth();int codeHeight = codeImage.getHeight();int x = (codeWidth - logoWidth) / 2;int y = (codeHeight - logoHeight) / 2;codeImageGraphics.drawImage(logoImage, x, y, logoWidth, logoHeight, null);Shape shape = new RoundRectangle2D.Float(x, y, logoWidth, logoHeight, 6, 6);codeImageGraphics.setStroke(new BasicStroke(3f));codeImageGraphics.draw(shape);codeImageGraphics.dispose();result = true;} catch (Exception e) {logger.error("QRCodeUtil-combineCodeAndInnerLogo 二维码中间插入logo失败:", e);result = false;}return result;}

将背景图填充上生成的二维码

 /*** 合成二维码image和背景图image** @param codeImage 二维码image* @param backImage 背景图image*/private static BufferedImage combineCodeAndBackImage(BufferedImage codeImage, BufferedImage backImage) {return combineCodeAndBackImage(codeImage, backImage, -1, 100);}/*** 合成二维码image和背景图image，指定二维码底部距离背景图底部的距离** @param codeImage    二维码image* @param backImage    背景图image* @param marginLeft   二维码距离背景图左边距离，如果为-1，则左右居中* @param marginBottom 二维码距离背景图底部距离* @return bufferedImage*/private static BufferedImage combineCodeAndBackImage(BufferedImage codeImage, BufferedImage backImage, int marginLeft, int marginBottom) {long start = System.currentTimeMillis();Graphics2D backImageGraphics = backImage.createGraphics();// 确定二维码在背景图的左上角坐标int x = marginLeft;if (marginLeft == -1) {x = (backImage.getWidth() - codeImage.getWidth()) / 2;}int y = backImage.getHeight() - codeImage.getHeight() - marginBottom;// 组合绘图backImageGraphics.drawImage(codeImage, x, y, codeImage.getWidth(), codeImage.getHeight(), null);backImageGraphics.dispose();logger.info("QRCodeUtil-combineCodeAndBackImage end. cost:{}", System.currentTimeMillis() - start);return backImage;}

保存图片文件到指定路径

 /*** 保存图片文件到指定路径** @param image      图片image* @param outputPath 指定路径* @return 操作结果*/private static boolean imageSaveToFile(BufferedImage image, String outputPath) {boolean result;try {//  为了保证大图背景不变色，formatName必须为"png"ImageIO.write(image, "png", new File(outputPath));result = true;} catch (IOException e) {logger.error("QRCodeUtil-imageSaveToFile 保存图片到{} 失败:,", outputPath, e);result = false;}return result;}

问题

下面列举一下当时遇到的一些问题

生成的二维码白边很大
默认使用zxing生成的二维码可以指定二维码长宽，但是整个图片规格是固定的，只能是固定的几个规格。这就导致如果我们需要指定生成二维码长宽的话，外边框会有留白。具体原因可以网上搜索，这里不赘述。
解决方法是重写zxing相应的方法（com.google.zxing.qrcode.QRCodeWriter#encode(java.lang.String,com.google.zxing.BarcodeFormat, int, int, java.util.Map)），重新缩放调整二维码大小

 /*** 修改encode生成逻辑，删除白边* 源码见com.google.zxing.qrcode.QRCodeWriter#encode(java.lang.String,* com.google.zxing.BarcodeFormat, int, int, java.util.Map)** @param contents 二维码内容* @param format   格式* @param width    宽度* @param height   长度* @param hints    hints* @return BitMatrix* @throws WriterException exception*/private static BitMatrix encode(String contents, BarcodeFormat format, int width, int height,Hashtable<EncodeHintType, ?> hints) throws WriterException {if (contents.isEmpty()) {throw new IllegalArgumentException("Found empty contents");}if (format != BarcodeFormat.QR_CODE) {throw new IllegalArgumentException("Can only encode QR_CODE, but got " + format);}if (width < 0 || height < 0) {throw new IllegalArgumentException("Requested dimensions are too small: " + width + 'x' +height);}ErrorCorrectionLevel errorCorrectionLevel = ErrorCorrectionLevel.L;int quietZone = QUIET_ZONE_SIZE;if (hints != null) {if (hints.containsKey(EncodeHintType.ERROR_CORRECTION)) {errorCorrectionLevel = ErrorCorrectionLevel.valueOf(hints.get(EncodeHintType.ERROR_CORRECTION).toString());}if (hints.containsKey(EncodeHintType.MARGIN)) {quietZone = Integer.parseInt(hints.get(EncodeHintType.MARGIN).toString());}}QRCode code = Encoder.encode(contents, errorCorrectionLevel, hints);return renderResult(code, width, height, quietZone);}/*** 对 zxing 的 QRCodeWriter 进行扩展, 解决白边过多的问题。去除白边的主要逻辑** @param code      qrcode* @param width     期望宽度* @param height    期望高度* @param quietZone quietZone* @return BitMatrix*/private static BitMatrix renderResult(QRCode code, int width, int height, int quietZone) {ByteMatrix input = code.getMatrix();if (input == null) {throw new IllegalStateException();}// xxx 二维码宽高相等, 即 qrWidth == qrHeightint inputWidth = input.getWidth();int inputHeight = input.getHeight();int qrWidth = inputWidth + (quietZone * 2);int qrHeight = inputHeight + (quietZone * 2);// 白边过多时, 缩放int minSize = Math.min(width, height);int scale = calculateScale(qrWidth, minSize);if (scale > 0) {int padding, tmpValue;// 计算边框留白padding = (minSize - qrWidth * scale) / QUIET_ZONE_SIZE * quietZone;tmpValue = qrWidth * scale + padding;if (width == height) {width = tmpValue;height = tmpValue;} else if (width > height) {width = width * tmpValue / height;height = tmpValue;} else {height = height * tmpValue / width;width = tmpValue;}}int outputWidth = Math.max(width, qrWidth);int outputHeight = Math.max(height, qrHeight);int multiple = Math.min(outputWidth / qrWidth, outputHeight / qrHeight);int leftPadding = (outputWidth - (inputWidth * multiple)) / 2;int topPadding = (outputHeight - (inputHeight * multiple)) / 2;BitMatrix output = new BitMatrix(outputWidth, outputHeight);for (int inputY = 0, outputY = topPadding; inputY < inputHeight; inputY++, outputY += multiple) {// Write the contents of this row of the barcodefor (int inputX = 0, outputX = leftPadding; inputX < inputWidth; inputX++, outputX += multiple) {if (input.get(inputX, inputY) == 1) {output.setRegion(outputX, outputY, multiple, multiple);}}}return output;}/*** 如果留白超过15% , 则需要缩放* (15% 可以根据实际需要进行修改)** @param qrCodeSize 二维码大小* @param expectSize 期望输出大小* @return 返回缩放比例, <= 0 则表示不缩放, 否则指定缩放参数*/private static int calculateScale(int qrCodeSize, int expectSize) {if (qrCodeSize >= expectSize) {return 0;}int scale = expectSize / qrCodeSize;int abs = expectSize - scale * qrCodeSize;if (abs < expectSize * 0.15) {return 0;}return scale;}/*** 缩放调整二维码大小，使之符合期望大小** @param matrix matrix* @param width  期望宽度* @param height 期望高度* @return bufferedImage*/private static BufferedImage resizeAndCreateBufferedImage(BitMatrix matrix, int width, int height) {int qrCodeWidth = matrix.getWidth();int qrCodeHeight = matrix.getHeight();BufferedImage qrCode = new BufferedImage(qrCodeWidth, qrCodeHeight, BufferedImage.TYPE_INT_RGB);for (int x = 0; x < qrCodeWidth; x++) {for (int y = 0; y < qrCodeHeight; y++) {qrCode.setRGB(x, y, matrix.get(x, y) ? BLACK : WHITE);}}// 若二维码的实际宽高和预期的宽高不一致, 则缩放if (qrCodeWidth != width || qrCodeHeight != height) {BufferedImage tmp = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);tmp.getGraphics().drawImage(qrCode.getScaledInstance(width, height,java.awt.Image.SCALE_SMOOTH), 0, 0, null);qrCode = tmp;}return qrCode;}

然后在调用生成二维码时，使用自定义的方法

生成的图片有颜色失真现象
我在使用的时候，如果生成的图片存储为jpg格式时，可能会出现图片颜色异常的情况。这是因为jpg格式采用了有损压缩，会导致图片失真。

解决方法是在保存到本地时（imageSaveToFile），存储为png格式

//  为了保证大图背景不变色，formatName必须为"png"
ImageIO.write(image, "png", new File(outputPath));

这种方法有一个不足，就是如果原图是png格式的话，图片一般都比较大，比较占用本地内存，网络传输时，也会比较慢，影响体验。

如果我们将原图转为jpg格式，可以有效减少图片的大小，生成的图片大小也会相应的减少。但是测试发现也可能出现图片失真的情况。后来发现，在读取图片文件时(createBufferedImage)，转存一下就可以解决这个问题。（具体为啥会这样，如果有人知道，欢迎指教）

// 防止写入jpg时出现失真异常，这里new一个新的image包一下
bi = new BufferedImage(tmpImage.getWidth(), tmpImage.getHeight(), BufferedImage.TYPE_INT_RGB);
bi.getGraphics().drawImage(tmpImage, 0, 0, null);

源码地址

https://download.csdn.net/download/somehow1002/12262631