What is the best way to transfer a file using Java?

Question

I am writing code for uploading a file from a client to my server and the performance isn't as fast as I think it should be.

I have the current code snippet that is doing the file transfer and I was wondering how I could speed up the transfer.

Sorry about all of the code:

InputStream fileItemInputStream ;
OutputStream saveFileStream;
int[] buffer;
while (fileItemInputStream.available() > 0) {
    buffer = Util.getBytesFromStream(fileItemInputStream);
    Util.writeIntArrToStream(saveFileStream, buffer);
}
saveFileStream.close();
fileItemInputStream.close();

The Util methods are as follows:

public static int[] getBytesFromStream(InputStream in, int size) throws IOException {
    int[] b = new int[size];
    int count = 0;
    while (count < size) {
        b[count++] = in.read();
    }
    return b;
}

and:

public static void writeIntArrToStream(OutputStream out, int[] arrToWrite) throws IOException {
    for (int i = 0; i < arrToWrite.length; i++) {
        out.write(arrToWrite[i]);
    }
}

Answer 1

Reading a single byte at a time will be horribly inefficient. You're also relying on available, which is rarely a good idea. (It will return 0 if there are no bytes currently available, but there may be more to come.)

This is the right sort of code to copy a stream:

public void copyStream(InputStream input, OutputStream output) throws IOException
{
    byte[] buffer = new byte[32*1024];
    int bytesRead;
    while ((bytesRead = input.read(buffer, 0, buffer.length)) > 0)
    {
        output.write(buffer, 0, bytesRead);
    }
}

(The caller should close both streams.)