把图片转成base64之后，上传到Java后台，如何判断原来图片的格式？

Question

我后台收到了字符串，解析成图片的时候，如何判断图片的原来的格式？

Answer 1

Convert the image to base64 encoding. The type of the file will be indicated at the beginning, such as the data:image/image type mentioned above.

Answer 2

data:image/png;base64,

Don’t they all have heads similar to this?