java实现二维码的生成与解析
简单介绍下二维码：二维码其实就是一种编码技术，只是这种编码技术是用在图片上了，将给定的一些文字，数字转换为一张经过特定编码的图片，而解析二维码则相反，就是将一张经过编码的图片解析为数字或者文字。
当然了，这种编码的低层实现并不是那么的简单，都是那些顶级研发人员做的事，我们只需要简单了解并知道怎么使用就可以了。
那么肯定是要导入jar包依赖的吧，那不用说，是要导包的，我用的是谷歌提供的一个com.google.zxing.core版本是3.3.0的。
下面我们直接创建一个maven项目，用maven管理jar包很方便，而且我们需要的jar包基本都可以从官网下载进行依赖的添加。
创建好maven项目后，在项目的pom.xml中添加依赖：
<dependency>
<groupId>com.google.zxing</groupId>
<artifactId>core</artifactId>
<version>3.3.0</version>
</dependency>
上面这段依赖可以直接到maven的官网进行copy，在maven依赖查询官网直接搜索zxing，我用的是3.3.0的版本。
相信大家对maven也已经比较熟悉了，具体大家可参考我的文章里面的《maven入门笔记》
jar包依赖添加完后，我们直接上代码：
第一个类：
package com.yc.qrcode; import java.awt.Graphics2D; import java.awt.geom.AffineTransform; import java.awt.image.BufferedImage; import com.google.zxing.LuminanceSource; public class BufferedImageLuminanceSource extends LuminanceSource { private final BufferedImage image; private final int left; private final int top; public BufferedImageLuminanceSource(BufferedImage image) { this(image, 0, 0, image.getWidth(), image.getHeight()); } public BufferedImageLuminanceSource(BufferedImage image, int left, int top, int width, int height) { super(width, height); int sourceWidth = image.getWidth(); int sourceHeight = image.getHeight(); if (left + width > sourceWidth || top + height > sourceHeight) { throw new IllegalArgumentException("Crop rectangle does not fit within image data."); } for (int y = top; y < top + height; y++) { for (int x = left; x < left + width; x++) { if ((image.getRGB(x, y) & 0xFF000000) == 0) { image.setRGB(x, y, 0xFFFFFFFF); // = white } } } this.image = new BufferedImage(sourceWidth, sourceHeight, BufferedImage.TYPE_BYTE_GRAY); this.image.getGraphics().drawImage(image, 0, 0, null); this.left = left; this.top = top; } public byte[] getRow(int y, byte[] row) { if (y < 0 || y >= getHeight()) { throw new IllegalArgumentException("Requested row is outside the image: " + y); } int width = getWidth(); if (row == null || row.length < width) { row = new byte[width]; } image.getRaster().getDataElements(left, top + y, width, 1, row); return row; } public byte[] getMatrix() { int width = getWidth(); int height = getHeight(); int area = width * height; byte[] matrix = new byte[area]; image.getRaster().getDataElements(left, top, width, height, matrix); return matrix; } public boolean isCropSupported() { return true; } public LuminanceSource crop(int left, int top, int width, int height) { return new BufferedImageLuminanceSource(image, this.left + left, this.top + top, width, height); } public boolean isRotateSupported() { return true; } public LuminanceSource rotateCounterClockwise() { int sourceWidth = image.getWidth(); int sourceHeight = image.getHeight(); AffineTransform transform = new AffineTransform(0.0, -1.0, 1.0, 0.0, 0.0, sourceWidth); BufferedImage rotatedImage = new BufferedImage(sourceHeight, sourceWidth, BufferedImage.TYPE_BYTE_GRAY); Graphics2D g = rotatedImage.createGraphics(); g.drawImage(image, transform, null); g.dispose(); int width = getWidth(); return new BufferedImageLuminanceSource(rotatedImage, top, sourceWidth - (left + width), getHeight(), width); } }
上面这个类是谷歌提供的帮助类
第二个类：
package com.zh.quartz_demo.util; import java.awt.BasicStroke; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.awt.Shape; import java.awt.geom.RoundRectangle2D; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import java.io.OutputStream; import java.util.HashMap; import java.util.Hashtable; import java.util.Map; import java.util.Random; import javax.imageio.ImageIO; import com.google.zxing.*; import com.google.zxing.common.BitMatrix; import com.google.zxing.common.HybridBinarizer; import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel; import com.zh.quartz_demo.test.BufferedImageLuminanceSource; public class QRCodeUtil { private static final String CHARSET = "utf-8"; private static final String FORMAT_NAME = "JPG"; // 二维码尺寸 private static final int QRCODE_SIZE = 300; // LOGO宽度 private static final int WIDTH = 60; // LOGO高度 private static final int HEIGHT = 60; private static BufferedImage createImage(String content, String imgPath, boolean needCompress) throws Exception { Hashtable hints = new Hashtable(); 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); 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) ? 0xFF000000 : 0xFFFFFFFF); } } if (imgPath == null || "".equals(imgPath)) { return image; } // 插入图片 QRCodeUtil.insertImage(image, imgPath, needCompress); return image; } private static void insertImage(BufferedImage source, String imgPath, boolean needCompress) throws Exception { File file = new File(imgPath); if (!file.exists()) { System.err.println("" + imgPath + " 该文件不存在！"); return; } Image src = ImageIO.read(new File(imgPath)); int width = src.getWidth(null); int height = src.getHeight(null); if (needCompress) { // 压缩LOGO if (width > WIDTH) { width = WIDTH; } if (height > HEIGHT) { height = HEIGHT; } Image image = src.getScaledInstance(width, height, Image.SCALE_SMOOTH); BufferedImage tag = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics g = tag.getGraphics(); g.drawImage(image, 0, 0, null); // 绘制缩小后的图 g.dispose(); src = image; } // 插入LOGO Graphics2D graph = source.createGraphics(); int x = (QRCODE_SIZE - width) / 2; int y = (QRCODE_SIZE - height) / 2; graph.drawImage(src, x, y, width, height, null); Shape shape = new RoundRectangle2D.Float(x, y, width, width, 6, 6); graph.setStroke(new BasicStroke(3f)); graph.draw(shape); graph.dispose(); } public static void encode(String content, String imgPath, String destPath, boolean needCompress) throws Exception { BufferedImage image = QRCodeUtil.createImage(content, imgPath, needCompress); mkdirs(destPath); ImageIO.write(image, FORMAT_NAME, new File(destPath)); } public static BufferedImage encode(String content, String imgPath, boolean needCompress) throws Exception { BufferedImage image = QRCodeUtil.createImage(content, imgPath, needCompress); return image; } public static void mkdirs(String destPath) { File file = new File(destPath); // 当文件夹不存在时，mkdirs会自动创建多层目录，区别于mkdir．(mkdir如果父目录不存在则会抛出异常) if (!file.exists() && !file.isDirectory()) { file.mkdirs(); } } public static void encode(String content, String imgPath, String destPath) throws Exception { QRCodeUtil.encode(content, imgPath, destPath, false); } // 被注释的方法 /* * public static void encode(String content, String destPath, boolean * needCompress) throws Exception { QRCodeUtil.encode(content, null, destPath, * needCompress); } */ public static void encode(String content, String destPath) throws Exception { QRCodeUtil.encode(content, null, destPath, false); } public static void encode(String content, String imgPath, OutputStream output, boolean needCompress) throws Exception { BufferedImage image = QRCodeUtil.createImage(content, imgPath, needCompress); ImageIO.write(image, FORMAT_NAME, output); } public static void encode(String content, OutputStream output) throws Exception { QRCodeUtil.encode(content, null, output, false); } public static String decode(File file) throws Exception { BufferedImage image; image = ImageIO.read(file); if (image == null) { return null; } BufferedImageLuminanceSource source = new BufferedImageLuminanceSource(image); BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source)); Result result; Hashtable hints = new Hashtable(); hints.put(DecodeHintType.CHARACTER_SET, CHARSET); result = new MultiFormatReader().decode(bitmap, hints); String resultStr = result.getText(); return resultStr; } public static String decode(String path) throws Exception { return QRCodeUtil.decode(new File(path)); } /* * 生成二维码 * @param content 二维码的内容 * @return BitMatrix对象 */ public static BitMatrix createCode(String content) throws IOException { //二维码的宽高 int width = 200; int height = 200; //其他参数，如字符集编码 Map<EncodeHintType, Object> hints = new HashMap<EncodeHintType, Object>(); hints.put(EncodeHintType.CHARACTER_SET, "UTF-8"); //容错级别为H hints.put(EncodeHintType.ERROR_CORRECTION , ErrorCorrectionLevel.H); //白边的宽度，可取0~4 hints.put(EncodeHintType.MARGIN , 0); BitMatrix bitMatrix = null; try { //生成矩阵，因为我的业务场景传来的是编码之后的URL，所以先解码 bitMatrix = new MultiFormatWriter().encode(content, BarcodeFormat.QR_CODE, width, height, hints); //bitMatrix = deleteWhite(bitMatrix); } catch (WriterException e) { e.printStackTrace(); } return bitMatrix; } }
上面这个是工具类，里面的方法我都写了注释，编码和解码方法都有多个重载方法，根据参数列表的不同，选择不同的方法执行。其中生成的二维码的图片的名字可以随机命名，也可以自己给定。我把随机命名的方法注释了，用的是给定图片名称。
主类：
public static void main(String[] args) { try { // 存放在二维码中的内容 String text = "我是小铭"; // 嵌入二维码的图片路径 String imgPath = "C:\\Users\\zipzia02\\Desktop\\微信图片_20191204154102.jpg";//"D:/img/59fc0ffb3ecf2.jpg"; // 生成的二维码的路径及名称 String destPath = "D:/img/jam.jpg"; //生成二维码 QRCodeUtil.encode(text, imgPath, destPath, true); // 解析二维码 String str = QRCodeUtil.decode(destPath); // 打印出解析出的内容 System.out.println(str); } catch (Exception e) { e.printStackTrace(); } }
请求api：
@GetMapping("getCode")
public void getCode(HttpServletResponse response) {
try {
// 设置响应流信息
response.setContentType("image/jpg");
response.setHeader("Pragma", "no-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
OutputStream stream = response.getOutputStream();
//获取一个二维码图片
BitMatrix bitMatrix = new QRCodeService().GetQRCode();//调用层
//以流的形式输出到前端
MatrixToImageWriter.writeToStream(bitMatrix, "jpg", stream);
} catch (Exception e) {
e.printStackTrace();
}
}
QRCodeService类：
public class QRCodeService { public BitMatrix GetQRCode() { BitMatrix bitMatrix = null; try{ String content = "包含的信息"; //调用接口生成二维码 QRCodeUtils.createCode(content); //获取一个二维码图片 bitMatrix = QRCodeUtils.createCode(content);
} catch (IOException e) { log.error("获取二维码异常", e); } return bitMatrix; } }
这里面的代码注释我都写得很清楚了，相信大家都可以看明白，其中：
生成二维码方法：
QRCodeUtil.encode(text, imgPath, destPath, true);
text：编码到二维码中的内容，这里是“我是小铭”
imgPath：要嵌入二维码的图片路径，如果不写或者为null则生成一个没有嵌入图片的纯净的二维码
destPath：生成的二维码的存放路径
true：表示将嵌入二维码的图片进行压缩，如果为“false”则表示不压缩。
解析二维码方法：
QRCodeUtil.decode(destPath);
destPath：将要解析的二维码的存放路径
该方法返回值为String类型，即返回解析出的文字或者数字等。
转载：https://blog.csdn.net/jam_fanatic/article/details/82818857
