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Java如何实现二维码

jiezi

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：

xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance”

xsi:schemaLocation=”http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/m…d”>

4.0.0

org.javaboy

QRCode

1.0-SNAPSHOT

com.google.zxing

core

3.3.0

工具类 1 (BufferedImageLuminanceSource)

不废话，直接上代码

package org.javaboy.util;

import java.awt.Graphics2D;

import java.awt.geom.AffineTransform;

import java.awt.image.BufferedImage;

import com.google.zxing.LuminanceSource;

/**

* @author bai

* @date 2020/7/1 9:27

*/

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。
XM 返佣 https://www.kaifx.cn/broker/x…

package org.javaboy.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.OutputStream;

import java.util.Hashtable;

import javax.imageio.ImageIO;

import com.google.zxing.BarcodeFormat;

import com.google.zxing.BinaryBitmap;

import com.google.zxing.DecodeHintType;

import com.google.zxing.EncodeHintType;

import com.google.zxing.MultiFormatReader;

import com.google.zxing.MultiFormatWriter;

import com.google.zxing.Result;

import com.google.zxing.common.BitMatrix;

import com.google.zxing.common.HybridBinarizer;

import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;

/**

* @author bai

* @date 2020/7/1 9:29

*/

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。

package org.javaboy;

import org.javaboy.util.QRCodeUtil;

/**

* @author bai

* @date 2020/7/1 9:31

*/

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);

}

}

退出移动版