<!-- https://mvnrepository.com/artifact/com.google.zxing/core  生成二维码 -->
<dependency>
    <groupId>com.google.zxing</groupId>
    <artifactId>core</artifactId>
    <version>3.3.0</version>
</dependency>
<dependency>
    <groupId>com.google.zxing</groupId>
    <artifactId>javase</artifactId>
    <version>3.3.0</version>
</dependency>

JSONObject jsonObject = new JSONObject();

  jsonObject.put("userName","alex");

  String s = jsonObject.toJSONString();

  System.out.println(s);


  // 定义图片宽度

  int width = 200;

  // 定义图片高度

  int height= 200;


  Map<EncodeHintType,Object> hints = new HashMap<EncodeHintType, Object>();

  hints.put(EncodeHintType.CHARACTER_SET,"UTF-8");

  BitMatrix bitMatrix = new MultiFormatWriter().encode(s, BarcodeFormat.QR_CODE,width,height,hints);


  String filePath = "D://";

  String fileName = "qrCode.jpg";


  // 定义路径对象

  Path path = FileSystems.getDefault().getPath(filePath,fileName);

  MatrixToImageWriter.writeToPath(bitMatrix,"jpg",path);


  System.out.println(path);