Java 如何实现二维码？

程序猿久一 07-20 129

前言：

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作者：红颜祸水nvn

来源：

步骤1

第一步首先创建一个普通的 Maven 项目，然后要实现二维码功能，我们肯定要使用别人提供好的 Jar 包，这里我用的是 google 提供的 jar，pom.xml 文件配置如下：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns=""
xmlns:xsi=""
xsi:schemaLocation=" ">
<modelVersion>4.0.0</modelVersion>
<groupId>org.javaboy</groupId>
<artifactId>QRCode</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<!-- 添加 google 提供的二维码依赖 -->
<dependency>
<groupId>com.google.zxing</groupId>
<artifactId>core</artifactId>
<version>3.3.0</version>
</dependency>
</dependencies>
</project>

步骤2

然后使用 google 提供的工具类，在项目根目录下创建一个 util 包，将所需要的工具类放进去。

工具类1 (BufferedImageLuminanceSource)

不废话，直接上代码

/**
* @author bai <br/>
* @date 2020/7/1 9:27<br/>
*/
publicclassBufferedImageLuminanceSourceextendsLuminanceSource{
private final BufferedImage image;
private final int left;
private final int top;
publicBufferedImageLuminanceSource(BufferedImage image) {
this(image, 0, 0, image.getWidth, image.getHeight);
}
publicBufferedImageLuminanceSource(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, );
this.left = left;
this.top = top;
}
@Override
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 == || row.length < width) {
row = new byte[width];
}
image.getRaster.getDataElements(left, top + y, width, 1, row);
return row;
}
@Override
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;
}
@Override
publicbooleanisCropSupported {
return true;
}
@Override
public LuminanceSource crop(int left, int top, int width, int height) {
return new BufferedImageLuminanceSource(image, this.left + left, this.top + top, width, height);
}
@Override
publicbooleanisRotateSupported {
return true;
}
@Override
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, );
g.dispose;
int width = getWidth;
return new BufferedImageLuminanceSource(rotatedImage, top, sourceWidth - (left + width), getHeight, width);
}
}

工具类2 (QRCodeUtil)

这里面可以修改一些参数，例如二维码的尺寸，宽高等等。

/**
* @author bai <br/>
* @date 2020/7/1 9:29<br/>
*/
publicclassQRCodeUtil{
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 == || "".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;
int height = src.getHeight;
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, ); // 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, );
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);
// String file = new Random.nextInt(99999999)+".jpg";
// ImageIO.write(image, FORMAT_NAME, new File(destPath+"/"+file));
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;
}
publicstaticvoidmkdirs(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, , destPath,
* needCompress); }
*/
public static void encode(String content, String destPath) throws Exception {
QRCodeUtil.encode(content, , 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, , output, false);
}
public static String decode(File file) throws Exception {
BufferedImage image;
image = ImageIO.read(file);
if (image == ) {
return ;
}
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));
}
}

启动类

这一步就是调用方法，一般大家使用这种功能都是为了实现业务，例如常见的扫描二维码跳转链接（页面），扫描二维码出现文字等等。有些二维码中间还带有 Logo 这种图片，将需要嵌入二维码的图片路径准备好就没有问题。

/**
* @author bai <br/>
* @date 2020/7/1 9:31<br/>
*/
public class QRCodeApplication {
public static void main(String[] args) throws Exception {
// 存放在二维码中的内容
// 二维码中的内容可以是文字，可以是链接等
String text = "";
// 嵌入二维码的图片路径
//String imgPath = "C:\\Users\\Administrator\\Pictures\\img\\dog.jpg";
// 生成的二维码的路径及名称
String destPath = "C:\\Users\\bai\\Pictures\\img\\code" + System.currentTimeMillis + ".jpg";
//生成二维码
QRCodeUtil.encode(text, , 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);
}
}