java生成二维码原理难学吗？用Java实现在线二维码系统
java生成二维码原理难学吗？用Java实现在线二维码系统/** * @author bai <br/> * @date 2020/7/1 9:29<br/> */ 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
作者：红颜祸水nvn
来源：http://suo.im/5R6ewH
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# 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="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<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。
不废话，直接上代码
/**
* @author bai <br/>
* @date 2020/7/1 9:27<br/>
*/
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;
}
@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 == null || 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
public boolean isCropSupported() {
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
public boolean isRotateSupported() {
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 null);
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/>
*/
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);
// 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;
}
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));
}
}
# 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 = "http://www.baidu.com";
// 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 null 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);
}
}
# 效果截图
