Using Java to realize the QR code generation and scanning function of form data

Use Java to realize the QR code generation and scanning function of form data

With the rapid development of the mobile Internet, QR codes have become a very common way of transmitting information. In many scenarios, we need to quickly transmit and scan the form data filled in by users in the form of QR codes. This article will use Java language to implement the QR code generation and scanning functions of form data, and provide code examples.

1. Generate QR code

We first need to use a third-party library in Java, such as ZXing, to generate QR code. ZXing is an open source QR code generation and parsing library, which provides a wealth of functions and APIs for us to use. We can use it by introducing ZXing's related dependencies into the project.

The following is a simple sample code that shows how to use the ZXing library to generate a QR code containing user form data.

import com.google.zxing.BarcodeFormat;
import com.google.zxing.MultiFormatWriter;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.QRCodeWriter;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.HashMap;

public class QRCodeGenerator {

    private static final int WIDTH = 300;
    private static final int HEIGHT = 300;

    public static void main(String[] args) {
        // 用户表单数据
        HashMap<String, String> formData = new HashMap<>();
        formData.put("name", "张三");
        formData.put("age", "25");

        // 生成二维码
        generateQRCode(formData);
    }

    public static void generateQRCode(HashMap<String, String> formData) {
        try {
            // 创建一个矩阵对象，用于表示生成的二维码图像
            BitMatrix bitMatrix = new MultiFormatWriter().encode(formData.toString(), BarcodeFormat.QR_CODE, WIDTH, HEIGHT, null);

            BufferedImage bufferedImage = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);

            // 迭代矩阵的每个像素点，设置颜色值
            for (int x = 0; x < WIDTH; x++) {
                for (int y = 0; y < HEIGHT; y++) {
                    bufferedImage.setRGB(x, y, bitMatrix.get(x, y) ? Color.BLACK.getRGB() : Color.WHITE.getRGB());
                }
            }

            // 将图像保存为文件
            File outputFile = new File("qrcode.png");
            ImageIO.write(bufferedImage, "png", outputFile);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

In the above example code, we use formData to represent the form data filled in by the user, and then use the encode method of the MultiFormatWriter class to generate Matrix representation of QR code image. After that, we iterate through each pixel of the matrix and set the corresponding color value according to its value, and finally save the image as a file.

2. Scan the QR code

After generating the QR code containing the form data, we also need to implement a scanning function to read the data in the QR code. The following is a simple sample code that demonstrates how to use the ZXing library to implement a simple QR code scanning function.

import com.google.zxing.BinaryBitmap;
import com.google.zxing.NotFoundException;
import com.google.zxing.RGBLuminanceSource;
import com.google.zxing.Reader;
import com.google.zxing.Result;
import com.google.zxing.common.HybridBinarizer;
import com.google.zxing.qrcode.QRCodeReader;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

public class QRCodeScanner {

    public static void main(String[] args) {
        // 扫描二维码
        scanQRCode("qrcode.png");
    }

    public static void scanQRCode(String imagePath) {
        try {
            // 读取二维码图像
            BufferedImage bufferedImage = ImageIO.read(new File(imagePath));
            RGBLuminanceSource source = new RGBLuminanceSource(bufferedImage.getWidth(), bufferedImage.getHeight(), getImagePixels(bufferedImage));
            BinaryBitmap binaryBitmap = new BinaryBitmap(new HybridBinarizer(source));

            // 创建一个二维码阅读器
            Reader reader = new QRCodeReader();

            // 解码二维码图像
            Result result = reader.decode(binaryBitmap);

            // 输出解码结果
            System.out.println(result.getText());
        } catch (IOException | NotFoundException e) {
            e.printStackTrace();
        }
    }

    private static int[] getImagePixels(BufferedImage bufferedImage) {
        int width = bufferedImage.getWidth();
        int height = bufferedImage.getHeight();
        int[] pixels = new int[width * height];
        bufferedImage.getRGB(0, 0, width, height, pixels, 0, width);
        return pixels;
    }
}

In the above example code, we read the QR code image through the read method of the ImageIO class and convert it to BinaryBitmap object. Then, we create a QRCodeReader object to decode the QR code image and obtain the decoding result through the decode method.

Summary:

This article uses Java language to implement the QR code generation and scanning functions of form data, and provides detailed code examples. Through these code examples, we can learn how to use the ZXing library to generate QR codes containing form data, and we can use the same library to implement the QR code scanning function. The QR code generation and scanning functions are very useful in many scenarios, such as event registration, electronic payment, etc. I hope this article can help you better understand and use Java to realize the QR code generation and scanning function of form data.

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