将一串编码转成二维码给前端

关于后台转换base64给前端

import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.QRCodeWriter;
import java.io.ByteArrayOutputStream;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import java.util.Base64;

　　　　　　　　　　　　　　 QRCodeWriter qrCodeWriter = new QRCodeWriter();
			BitMatrix bitMatrix = qrCodeWriter.encode(userCoupon.getCoupon_no(), BarcodeFormat.QR_CODE, 375, 375);
			ByteArrayOutputStream pngOutputStream = new ByteArrayOutputStream();
			MatrixToImageWriter.writeToStream(bitMatrix, "PNG", pngOutputStream);
			byte[] pngData = pngOutputStream.toByteArray();
			Base64.Encoder encoder = Base64.getEncoder();
			String base64Img = encoder.encodeToString(pngData);
			base64Img = base64Img.replaceAll("\n", "").replaceAll("\r", "");
			return "data:image/jpg;base64,"+base64Img;