Cacher is the code snippet organizer for pro developers

<dependency>
    <groupId>com.google.zxing</groupId>
    <artifactId>core</artifactId>
    <version>3.0.0</version>
</dependency>
<dependency>
    <groupId>com.google.zxing</groupId>
    <artifactId>javase</artifactId>
    <version>3.0.0</version>
</dependency>

private static void createQrCode(OutputStream outputStream, String content, int qrCodeSize, String imageFormat) throws WriterException, IOException {
    QRCodeWriter writer = new QRCodeWriter();
    Hashtable<EncodeHintType, Object> hints = new Hashtable<>();
    hints.put(EncodeHintType.MARGIN, 0);
    BitMatrix m = writer.encode(content, BarcodeFormat.QR_CODE, qrCodeSize, qrCodeSize, hints);
    MatrixToImageWriter.writeToStream(m, imageFormat, outputStream);
}

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
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.EncodeHintType;
import com.google.zxing.LuminanceSource;
import com.google.zxing.ReaderException;
import com.google.zxing.Result;
import com.google.zxing.WriterException;
import com.google.zxing.client.j2se.BufferedImageLuminanceSource;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.common.HybridBinarizer;
import com.google.zxing.qrcode.QRCodeReader;
import com.google.zxing.qrcode.QRCodeWriter;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;

/**
 * 二维码生成和读的工具类
 */
public class QrCodeCreateUtil {

    /**
     * 生成包含字符串信息的二维码图片
     *
     * @param outputStream 文件输出流路径
     * @param content      二维码携带信息
     * @param qrCodeSize   二维码图片大小
     * @param imageFormat  二维码的格式
     * @throws WriterException
     * @throws IOException
     */
    public static boolean createQrCode(OutputStream outputStream, String content, int qrCodeSize, String imageFormat) throws WriterException, IOException {
        //设置二维码纠错级别ＭＡＰ
        Hashtable<EncodeHintType, ErrorCorrectionLevel> hintMap = new Hashtable<EncodeHintType, ErrorCorrectionLevel>();
        hintMap.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.L);  // 矫错级别
        QRCodeWriter qrCodeWriter = new QRCodeWriter();
        //创建比特矩阵(位矩阵)的QR码编码的字符串
        BitMatrix byteMatrix = qrCodeWriter.encode(content, BarcodeFormat.QR_CODE, qrCodeSize, qrCodeSize, hintMap);
        // 使BufferedImage勾画QRCode  (matrixWidth 是行二维码像素点)
        int matrixWidth = byteMatrix.getWidth();
        BufferedImage image = new BufferedImage(matrixWidth - 200, matrixWidth - 200, BufferedImage.TYPE_INT_RGB);
        image.createGraphics();
        Graphics2D graphics = (Graphics2D) image.getGraphics();
        graphics.setColor(Color.WHITE);
        graphics.fillRect(0, 0, matrixWidth, matrixWidth);
        // 使用比特矩阵画并保存图像
        graphics.setColor(Color.BLACK);
        for (int i = 0; i < matrixWidth; i++) {
            for (int j = 0; j < matrixWidth; j++) {
                if (byteMatrix.get(i, j)) {
                    graphics.fillRect(i - 100, j - 100, 1, 1);
                }
            }
        }
        return ImageIO.write(image, imageFormat, outputStream);
    }

    /**
     * 读二维码并输出携带的信息
     */
    public static void readQrCode(InputStream inputStream) throws IOException {
        //从输入流中获取字符串信息
        BufferedImage image = ImageIO.read(inputStream);
        //将图像转换为二进制位图源
        LuminanceSource source = new BufferedImageLuminanceSource(image);
        BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
        QRCodeReader reader = new QRCodeReader();
        Result result = null;
        try {
            result = reader.decode(bitmap);
        } catch (ReaderException e) {
            e.printStackTrace();
        }
        System.out.println(result.getText());
    }

    /**
     * 测试代码
     *
     * @throws WriterException
     */
    public static void main(String[] args) throws IOException, WriterException {
        createQrCode(new FileOutputStream(new File("d:\\qrcode.jpg")), "http://dmrs.me", 900, "JPEG");
        readQrCode(new FileInputStream(new File("d:\\qrcode.jpg")));
    }

}