public String generalQRCode(String url){
          Hashtable hints= new Hashtable(); 
          hints.put(EncodeHintType.CHARACTER_SET, "utf-8"); 
          String binary = null;
          try {
　　　　　　　　//400,400是二维码图片宽高
              BitMatrix bitMatrix = new MultiFormatWriter().encode(
              url, BarcodeFormat.QR_CODE, 400, 400, hints);

              // 实现一： 输出图片到指定目录
              // File outputFile = new File("d://1.jpg");
//                      MatrixToImageWriter.writeToFile(bitMatrix, "png", outputFile);

              // 实现二：生成二维码图片并将图片转为二进制传递给前台
              // 1、读取文件转换为字节数组
              ByteArrayOutputStream out = new ByteArrayOutputStream();
              BufferedImage image = toBufferedImage(bitMatrix);
              //// 
              ImageIO.write(image, "png", out);
              byte[] bytes = out.toByteArray();

              // 2、将字节数组转为二进制
              BASE64Encoder encoder = new BASE64Encoder(); 
              binary = encoder.encodeBuffer(bytes).trim(); 

              } catch (Exception e) {
              e.printStackTrace();
              } 
          return "data:image/png;base64,"+binary;
     }
     public static BufferedImage toBufferedImage(BitMatrix matrix) {
        int width = matrix.getWidth();
        int height = matrix.getHeight();
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        for (int x = 0; x < width; x++) {
          for (int y = 0; y < height; y++) {
            image.setRGB(x, y, matrix.get(x, y) ? 0xFF000000 : 0xFFFFFFFF);
          }
        }
        
        return image;
      }