如何使用 ZXing 库用Java生成和读取二维码

QRCode缩写为Quic Response Code ，我们现在对 QRCodes 非常熟悉。它用于经过身份验证的快速在线支付。二维码使用四种标准化的编码模式（数字、字母数字、字节/二进制和汉字）来有效地存储数据；也可以使用扩展。
QRCode是黑白方块的排列，可以使用各种 QRCode 扫描仪读取，并且在今天很方便，因为每个智能手机都有 QRcode 扫描仪应用程序。

用于生成二维码的库（ZXing）

ZXing（“斑马线”）是Java中用于二维码处理的流行 API。它的库有多个组件，我们将在我们的Java示例中使用“核心”来创建 QR 码。

如何生成二维码？

以下代码是创建 QR 码图像的示例。

1. 从这里下载 ZXING 库。
2. 在maven 文件中添加 ZXING 依赖项。

XML

    
        com.google.zxing
        core
        3.3.0
    
    
        com.google.zxing
        javase
        3.3.0
    

1. 编写代码生成二维码，并将其保存为原生文件夹中的jpg 文件。
   

Java

// Java code to generate QR code
 
import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.MultiFormatWriter;
import com.google.zxing.NotFoundException;
import com.google.zxing.WriterException;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;
 
public class MyQr {
 
    // Function to create the QR code
    public static void createQR(String data, String path,
                                String charset, Map hashMap,
                                int height, int width)
        throws WriterException, IOException
    {
 
        BitMatrix matrix = new MultiFormatWriter().encode(
            new String(data.getBytes(charset), charset),
            BarcodeFormat.QR_CODE, width, height);
 
        MatrixToImageWriter.writeToFile(
            matrix,
            path.substring(path.lastIndexOf('.') + 1),
            new File(path));
    }
   
    // Driver code
    public static void main(String[] args)
        throws WriterException, IOException,
               NotFoundException
    {
 
        // The data that the QR code will contain
        String data = "www.geeksforgeeks.org";
 
        // The path where the image will get saved
        String path = "demo.png";
 
        // Encoding charset
        String charset = "UTF-8";
 
        Map hashMap
            = new HashMap();
 
        hashMap.put(EncodeHintType.ERROR_CORRECTION,
                    ErrorCorrectionLevel.L);
 
        // Create the QR code and save
        // in the specified folder
        // as a jpg file
        createQR(data, path, charset, hashMap, 200, 200);
        System.out.println("QR Code Generated!!! ");
    }
}

输出文件名为demo.jpg

扫描此二维码后，您将被重定向到geeksforgeeks主页。

如何生成二维码？

生成二维码后，我们还可以使用ZXing 库读取二维码图像文件。下面是执行此操作的代码。

Java

// Java code to read the QR code
 
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import javax.imageio.ImageIO;
import com.google.zxing.BarcodeFormat;
import com.google.zxing.BinaryBitmap;
import com.google.zxing.EncodeHintType;
import com.google.zxing.MultiFormatReader;
import com.google.zxing.MultiFormatWriter;
import com.google.zxing.NotFoundException;
import com.google.zxing.Result;
import com.google.zxing.WriterException;
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.decoder.ErrorCorrectionLevel;
 
public class QRCode {
 
     
    // Function to read the QR file
    public static String readQR(String path, String charset,
                                Map hashMap)
        throws FileNotFoundException, IOException,
               NotFoundException
    {
        BinaryBitmap binaryBitmap
            = new BinaryBitmap(new HybridBinarizer(
                new BufferedImageLuminanceSource(
                    ImageIO.read(
                        new FileInputStream(path)))));
 
        Result result
            = new MultiFormatReader().decode(binaryBitmap);
 
        return result.getText();
    }
   
    // Driver code
    public static void main(String[] args)
        throws WriterException, IOException,
               NotFoundException
    {
 
        // Path where the QR code is saved
        String path = "F:\user\QRCodes";
 
        // Encoding charset
        String charset = "UTF-8";
 
        Map hashMap
            = new HashMap();
 
        hintMap.put(EncodeHintType.ERROR_CORRECTION,
                    ErrorCorrectionLevel.L);
 
        System.out.println(
            "QRCode output: "
            + readQRCode(filePath, charset, hintMap));
    }
 
}

输出：

QRCode output: www.geeksforgeeks.org