Question

I have a piece of code like so…

FileInputStream fi = new FileInputStream(filein);
GZIPInputStream gzis = new GZIPInputStream(fi);
ByteBuffer bbuffer = ByteBuffer.allocate(115200);

The fi.available() is 84300, but the gzis.available() is only 1. The file(filein) is already compressed.

I want to read the file, uncompress it, and finally put it into my ByteBuffer bbufer.

How could I realize this operation?

Answer 1

gzis.available() = 1; doesn’t mean that there is a problem, it simply means that you can only read 1 byte of information from the Stream before you can continue. you can’t expect that the entire uncompressed file will be available in a single command.

To read the entire file, you will need to have a loop that continues to read over the InputStream until you have all the data. For example…

int bytesRead = 0;
int bytesAvailable = gzis.available();
while (bytesAvailable > 0){
    gzis.read(bbuffer,bytesRead,bytesAvailable);
    bytesRead += bytesAvailable;
    bytesAvailable = gzis.available();
}

Of course, if you aren’t sure of the final size of the uncompressed file, you’ll need to add in extra code to allow your bbuffer to be resized if you need more room.