Java 生成二維碼以Base64串存DB，讀取網頁顯示

QrcodeUtils.java 源碼：

package com.pay.utils;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.MultiFormatWriter;
import com.google.zxing.common.BitMatrix;
import sun.misc.BASE64Encoder;

import javax.imageio.ImageIO;
import javax.swing.filechooser.FileSystemView;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Map;

public class QrCodeUtil {

    public static void main(String[] args) {
        String url = "http://www.baidu.com";
        String path = FileSystemView.getFileSystemView().getHomeDirectory() +             File.separator + "testQrcode";
        String fileName = "temp.jpg";
        createQrCode(url, path, fileName);
    }

    public static String createQrCode(String url) {
        try {
            Map<EncodeHintType, String> hints = new HashMap<>();
            hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
            BitMatrix bitMatrix = new MultiFormatWriter().encode(url, BarcodeFormat.QR_CODE, 400, 400, hints);

// 二維碼圖片下載至本地
//            File file = new File(path, fileName);
//            if (file.exists() || ((file.getParentFile().exists() || file.getParentFile().mkdirs()) && file.createNewFile())) {
//                writeToFile(bitMatrix, "jpg", file);
//                System.out.println("搞定：" + file);
//            }

            // 1、讀取文件轉換爲字節數組
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            BufferedImage image = toBufferedImage(bitMatrix);
            //轉換成png格式的IO流
            ImageIO.write(image, "png", out);
            byte[] bytes = out.toByteArray();

            // 2、將字節數組轉爲二進制
            BASE64Encoder encoder = new BASE64Encoder();
            String binary = encoder.encodeBuffer(bytes).trim();
            System.out.println(binary);
            return binary;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    static void writeToFile(BitMatrix matrix, String format, File file) throws IOException {
        BufferedImage image = toBufferedImage(matrix);
        if (!ImageIO.write(image, format, file)) {
            throw new IOException("Could not write an image of format " + format + " to " + file);
        }
    }

    static void writeToStream(BitMatrix matrix, String format, OutputStream stream) throws IOException {
        BufferedImage image = toBufferedImage(matrix);
        if (!ImageIO.write(image, format, stream)) {
            throw new IOException("Could not write an image of format " + format);
        }
    }

    private static final int BLACK = 0xFF000000;
    private static final int WHITE = 0xFFFFFFFF;

    private static BufferedImage toBufferedImage(BitMatrix matrix) {
        int width = matrix.getWidth();
        int height = matrix.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, matrix.get(x, y) ? BLACK : WHITE);
            }
        }
        return image;
    }
}

pom引入：

        <!-- https://mvnrepository.com/artifact/com.google.zxing/core -->
        <dependency>
            <groupId>com.google.zxing</groupId>
            <artifactId>core</artifactId>
            <version>3.3.0</version>
        </dependency>

前端頁面顯示：

<img src="data:image/png;base64,' + value + '" width="70px" height="70px"></img>