代码生成（Java生成二维码）

Java中可以使用第三方库，比如ZXing，来生成二维码。以下是一个简单的Java程序示例，使用ZXing库生成二维码：

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.WriterException;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.QRCodeWriter;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;

public class QRCodeGenerator {

    private static final String QR_CODE_IMAGE_PATH = "./MyQRCode.png";

    private static void generateQRCodeImage(String text, int width, int height, String filePath)
            throws WriterException, IOException {
        QRCodeWriter qrCodeWriter = new QRCodeWriter();
        BitMatrix bitMatrix = qrCodeWriter.encode(text, BarcodeFormat.QR_CODE, width, height);

        BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        for (int x = 0; x < width; x++) {
            for (int y = 0; y < height; y++) {
                int grayValue = (bitMatrix.get(x, y) ? 0 : 1) & 0xff;
                bufferedImage.setRGB(x, y, (grayValue == 0 ? 0 : 0xFFFFFF));
            }
        }

        File qrCodeImage = new File(filePath);
        ImageIO.write(bufferedImage, "png", qrCodeImage);
    }

    public static void main(String[] args) {
        String text = "https://www.example.com";
        int width = 350;
        int height = 350;

        try {
            generateQRCodeImage(text, width, height, QR_CODE_IMAGE_PATH);
        } catch (WriterException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

在这个示例中，我们使用了QRCodeWriter类来生成二维码，并将结果保存到PNG文件中。你可以根据需要调整代码中的参数，比如二维码的尺寸、纠错级别等。