一、简介

　　二维码又称二维条码，常见的二维码为QR Code，QR全称Quick Response，是一个近几年来移动设备上超流行的一种编码方式，它比传统的Bar Code条形码能存更多的信息，也能表示更多的数据类型。
　　二维条码/二维码（2-dimensional bar code）是用某种特定的几何图形按一定规律在平面（二维方向上）分布的黑白相间的图形记录数据符号信息的；在代码编制上巧妙地利用构成计算机内部逻辑基础的“0”、“1”比特流的概念，使用若干个与二进制相对应的几何形体来表示文字数值信息，通过图象输入设备或光电扫描设备自动识读以实现信息自动处理：它具有条码技术的一些共性：每种码制有其特定的字符集；每个字符占有一定的宽度；具有一定的校验功能等。同时还具有对不同行的信息自动识别功能、及处理图形旋转变化点。

二、基于Zxing框架的简单实现

1、引入框架

        <!-- https://mvnrepository.com/artifact/com.google.zxing/core -->
        <dependency>
            <groupId>com.google.zxing</groupId>
            <artifactId>core</artifactId>
            <version>3.3.3</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.google.zxing/javase -->
        <dependency>
            <groupId>com.google.zxing</groupId>
            <artifactId>javase</artifactId>
            <version>3.3.3</version>
        </dependency>

2、编写工具类

package com.back.web;

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.Hashtable;

import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;

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.client.j2se.BufferedImageLuminanceSource;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.common.HybridBinarizer;
import com.google.zxing.qrcode.QRCodeWriter;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;

@SuppressWarnings({ "rawtypes", "unchecked" })
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, String orderNumber, boolean needCompress)
            throws Exception {
        BufferedImage image = QRCodeUtil.createImage(content, imgPath, needCompress);
        mkdirs(destPath);
        String file = orderNumber + ".jpg";
        ImageIO.write(image, FORMAT_NAME, new File(destPath + "/" + file));
    }

    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 orderNumber, String destPath) throws Exception {
        QRCodeUtil.encode(content, imgPath, destPath, orderNumber, false);
    }

    public static void encode(String content, String destPath, String orderNumber, boolean needCompress)
            throws Exception {
        QRCodeUtil.encode(content, null, destPath, orderNumber, 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));
    }

    /**
     * 
     * @param content
     * @param response
     *            二维码图片流
     * @throws IOException
     */
    public static void encode(String content, HttpServletResponse response) throws Exception {
        ServletOutputStream stream = null;
        try {
            int size = 301;
            stream = response.getOutputStream();
            QRCodeWriter writer = new QRCodeWriter();
            BitMatrix m = writer.encode(content, BarcodeFormat.QR_CODE, size, size);
            MatrixToImageWriter.writeToStream(m, "jpg", stream);
        } catch (Exception e) {
            // e.printStackTrace();
        } finally {
            if (stream != null) {
                stream.flush();
                stream.close();

            }
        }
    }

    public static void main(String[] args) throws Exception {
        // String text = "weixin://wxpay/bizpayurl?pr=Q4ef5N0";
        String text = "https://qr.alipay.com/bax01040znvilzajvmb600cd";
        QRCodeUtil.encode(text, "F:", "666", true);
    }
}

三、示例

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Java - 二维码

一、简介

二、基于Zxing框架的简单实现

1、引入框架

2、编写工具类

三、示例