Question

I want to convert an InputStream object representing an image file to a BufferedImage object and after performing some operations on the BufferedImage convert it back to an InputStream so that it can be written to disk.I dont want to create a file object on disk first in order to prevent additional IO overhead.

I think i can do the following to convert a BufferedImage to InputStream

ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
ImageIO.write(image,fileExtension, outputStream);
InputStream inputStream = new ByteArrayInputStream(outputStream.toByteArray());

Is that correct ?. Also, i have the following two questions

1. How to get BufferedImage object from an InputStream object
2. Can i get the filesize directly from the InputStream object ?

Some example would really help

Thank You

Answer 1

1. Take a look at the read(InputStream stream) method of ImageIO
2. No, you can have a peek using available() but this does not guarantee the size of the stream (it works for FileInputStream)
3. You can’t write to an input stream (as its name states it, it is an input, not an output). To write, you need an OutputStream and you can use the write(RenderedImage im, String formatName, OutputStream output) of ImageIO