Java QR code generation and parsing sample code

QR code is a barcode image that uses black and white flat geometric figures to record text, pictures, URLs and other information through corresponding encoding algorithms. As shown below

Characteristics of QR code:

1. High-density coding, large information capacity

It can accommodate up to 1850 uppercase letters or 2710 numbers or 1108 bytes, or more than 500 Chinese characters, which is about dozens of times higher than the information capacity of ordinary barcodes.

2. Wide encoding range

This barcode can encode pictures, sounds, text, signatures, fingerprints and other digitized information and express it with barcodes; it can Represents text in multiple languages; can represent image data.

3. Strong fault tolerance and error correction function

This allows the 2D barcode to be read correctly even if it is partially damaged due to perforations, stains, etc. , information can still be recovered if 50% of the damaged area is damaged.

4. High decoding reliability

It is much lower than ordinary barcode decoding error rate of 2 parts per million, and the bit error rate does not exceed 10 million one part.

5. Encryption measures can be introduced

Good confidentiality and anti-counterfeiting properties.

6. Low cost, easy to make, durable

Because of the above characteristics, QR codes are becoming more and more popular and their applications are becoming more and more widespread ( For detailed information, please see Baidu Encyclopedia (the introduction is not the focus of this article), so knowing how to develop QR codes is a very good knowledge reserve, so this article will explain how to generate and parse QR codes.

1. Java

Required jar package: QRCode.jar

http://sourceforge.jp/projects/qrcode/

TwoDimensionCode class: QR code operation core class

package qrcode;
 
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
 
import javax.imageio.ImageIO;
 
import jp.sourceforge.qrcode.QRCodeDecoder;
import jp.sourceforge.qrcode.exception.DecodingFailedException;
 
import com.swetake.util.Qrcode;
 
public class TwoDimensionCode {
  
 /**
 * 生成二维码(QRCode)图片
 * @param content 存储内容
 * @param imgPath 图片路径
 */
 public void encoderQRCode(String content, String imgPath) {
 this.encoderQRCode(content, imgPath, "png", 7);
 }
  
 /**
 * 生成二维码(QRCode)图片
 * @param content 存储内容
 * @param output 输出流
 */
 public void encoderQRCode(String content, OutputStream output) {
 this.encoderQRCode(content, output, "png", 7);
 }
  
 /**
 * 生成二维码(QRCode)图片
 * @param content 存储内容
 * @param imgPath 图片路径
 * @param imgType 图片类型
 */
 public void encoderQRCode(String content, String imgPath, String imgType) {
 this.encoderQRCode(content, imgPath, imgType, 7);
 }
  
 /**
 * 生成二维码(QRCode)图片
 * @param content 存储内容
 * @param output 输出流
 * @param imgType 图片类型
 */
 public void encoderQRCode(String content, OutputStream output, String imgType) {
 this.encoderQRCode(content, output, imgType, 7);
 }
 
 /**
 * 生成二维码(QRCode)图片
 * @param content 存储内容
 * @param imgPath 图片路径
 * @param imgType 图片类型
 * @param size 二维码尺寸
 */
 public void encoderQRCode(String content, String imgPath, String imgType, int size) {
 try {
 BufferedImage bufImg = this.qRCodeCommon(content, imgType, size);
  
 File imgFile = new File(imgPath);
 // 生成二维码QRCode图片
 ImageIO.write(bufImg, imgType, imgFile);
 } catch (Exception e) {
 e.printStackTrace();
 }
 }
 
 /**
 * 生成二维码(QRCode)图片
 * @param content 存储内容
 * @param output 输出流
 * @param imgType 图片类型
 * @param size 二维码尺寸
 */
 public void encoderQRCode(String content, OutputStream output, String imgType, int size) {
 try {
 BufferedImage bufImg = this.qRCodeCommon(content, imgType, size);
 // 生成二维码QRCode图片
 ImageIO.write(bufImg, imgType, output);
 } catch (Exception e) {
 e.printStackTrace();
 }
 }
  
 /**
 * 生成二维码(QRCode)图片的公共方法
 * @param content 存储内容
 * @param imgType 图片类型
 * @param size 二维码尺寸
 * @return
 */
 private BufferedImage qRCodeCommon(String content, String imgType, int size) {
 BufferedImage bufImg = null;
 try {
 Qrcode qrcodeHandler = new Qrcode();
 // 设置二维码排错率，可选L(7%)、M(15%)、Q(25%)、H(30%)，排错率越高可存储的信息越少，但对二维码清晰度的要求越小
 qrcodeHandler.setQrcodeErrorCorrect('M');
 qrcodeHandler.setQrcodeEncodeMode('B');
 // 设置设置二维码尺寸，取值范围1-40，值越大尺寸越大，可存储的信息越大
 qrcodeHandler.setQrcodeVersion(size);
 // 获得内容的字节数组，设置编码格式
 byte[] contentBytes = content.getBytes("utf-8");
 // 图片尺寸
 int imgSize = 67 + 12 * (size - 1);
 bufImg = new BufferedImage(imgSize, imgSize, BufferedImage.TYPE_INT_RGB);
 Graphics2D gs = bufImg.createGraphics();
 // 设置背景颜色
 gs.setBackground(Color.WHITE);
 gs.clearRect(0, 0, imgSize, imgSize);
 
 // 设定图像颜色> BLACK
 gs.setColor(Color.BLACK);
 // 设置偏移量，不设置可能导致解析出错
 int pixoff = 2;
 // 输出内容> 二维码
 if (contentBytes.length > 0 && contentBytes.length < 800) {
 boolean[][] codeOut = qrcodeHandler.calQrcode(contentBytes);
 for (int i = 0; i < codeOut.length; i++) {
 for (int j = 0; j < codeOut.length; j++) {
 if (codeOut[j][i]) {
 gs.fillRect(j * 3 + pixoff, i * 3 + pixoff, 3, 3);
 }
 }
 }
 } else {
 throw new Exception("QRCode content bytes length = " + contentBytes.length + " not in [0, 800].");
 }
 gs.dispose();
 bufImg.flush();
 } catch (Exception e) {
 e.printStackTrace();
 }
 return bufImg;
 }
  
 /**
 * 解析二维码（QRCode）
 * @param imgPath 图片路径
 * @return
 */
 public String decoderQRCode(String imgPath) {
 // QRCode 二维码图片的文件
 File imageFile = new File(imgPath);
 BufferedImage bufImg = null;
 String content = null;
 try {
 bufImg = ImageIO.read(imageFile);
 QRCodeDecoder decoder = new QRCodeDecoder();
 content = new String(decoder.decode(new TwoDimensionCodeImage(bufImg)), "utf-8"); 
 } catch (IOException e) {
 System.out.println("Error: " + e.getMessage());
 e.printStackTrace();
 } catch (DecodingFailedException dfe) {
 System.out.println("Error: " + dfe.getMessage());
 dfe.printStackTrace();
 }
 return content;
 }
  
 /**
 * 解析二维码（QRCode）
 * @param input 输入流
 * @return
 */
 public String decoderQRCode(InputStream input) {
 BufferedImage bufImg = null;
 String content = null;
 try {
 bufImg = ImageIO.read(input);
 QRCodeDecoder decoder = new QRCodeDecoder();
 content = new String(decoder.decode(new TwoDimensionCodeImage(bufImg)), "utf-8"); 
 } catch (IOException e) {
 System.out.println("Error: " + e.getMessage());
 e.printStackTrace();
 } catch (DecodingFailedException dfe) {
 System.out.println("Error: " + dfe.getMessage());
 dfe.printStackTrace();
 }
 return content;
 }
 
 public static void main(String[] args) {
 String imgPath = "G:/TDDOWNLOAD/Michael_QRCode.png";
 String encoderContent = "Hello 大大、小小,welcome to QRCode!" + "\nMyblog [ http://sjsky.iteye.com ]" + "\nEMail [ sjsky007@gmail.com ]";
 TwoDimensionCode handler = new TwoDimensionCode();
 handler.encoderQRCode(encoderContent, imgPath, "png");
// try {
// OutputStream output = new FileOutputStream(imgPath);
// handler.encoderQRCode(content, output);
// } catch (Exception e) {
// e.printStackTrace();
// }
 System.out.println("========encoder success");
  
  
 String decoderContent = handler.decoderQRCode(imgPath);
 System.out.println("解析结果如下：");
 System.out.println(decoderContent);
 System.out.println("========decoder success!!!");
 }
}

TwoDimensionCodeImage class: QR code image object

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