java不是很熟悉，特别是IO，求有经验的同学帮帮忙
解决方案
1.byte[] -> BufferedImage
BufferedImage bi1 = ImageIO.read(new ByteArrayInputStream(byte[]));
2.BufferedImage -> byte[]
ByteArrayOutputStream out = new ByteArrayOutputStream();
ImageIO.write(img, "PNG", out);
out.toByteArray()