java怎么生成二维码

Java可以使用第三方库zxing来生成二维码，具体实现可以参考以下代码：

import java.awt.image.BufferedImage;
import java.io.File;
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.EncodeHintType;
import com.google.zxing.WriterException;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.QRCodeWriter;

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();
        Map<EncodeHintType, Object> hints = new HashMap<>();
        hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
        BitMatrix bitMatrix = qrCodeWriter.encode(text, BarcodeFormat.QR_CODE, width, height, hints);

        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) {
        try {
            generateQRCodeImage("https://www.baidu.com", 350, 350, QR_CODE_IMAGE_PATH);
            System.out.println("二维码生成成功！");
        } catch (WriterException e) {
            System.out.println("二维码生成失败，WriterException :: " + e.getMessage());
        } catch (IOException e) {
            System.out.println("二维码生成失败，IOException :: " + e.getMessage());
        }
    }
}