BufferedImage缓存图片（data:image/jpg;base64,）转换base64输出与解析

1、比如说二维码图片数据data，不想落地生成jpg文件，通过java缓存文件转换base64输出到页面展示，那么java后端处理写法参考如下：

　　　　　　　　　 InputStream is = new ByteArrayInputStream(data);
                BufferedImage img = ImageIO.read(is);
                BufferedImage bi = new BufferedImage(IMG_WIDTH, IMG_WIDTH, BufferedImage.TYPE_INT_RGB);
                Graphics g = bi.getGraphics();
                g.drawImage(img, 0, 0, IMG_WIDTH, IMG_WIDTH, Color.LIGHT_GRAY, null);
                g.dispose();
                is.close();
                // bufferImage->base64
                ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
                ImageIO.write(img, "jpg", outputStream);
                String base64Img = Base64Util.encode2Str(outputStream.toByteArray());
                res = "data:image/jpg;base64," + base64Img.toString();
                outputStream.close();

2、反过来，把页面上base64展示的图片，传递到java端解析出来的写法如下：

　　　　　　　request.setCharacterEncoding("utf-8");  //设置编码
           　　
            String s[] = src.split(",");
            byte[] src1 = Base64.decodeBase64(s[1]);
            ByteArrayInputStream inputStream = new ByteArrayInputStream(src1);
            BufferedImage bi = ImageIO.read(inputStream);
            String str = MatrixUtils.decode(bi);