track progress of copying files

Question

I am trying to track the progress of a compression progress. ATM I am doing it like this:

public static void compressGzipTest(final OutputStream os, final File source) throws CompressorException,
            IOException
    {
        final CountingInputStream cis = new CountingInputStream(new FileInputStream(source));
        final GzipCompressorOutputStream gzipOut = (GzipCompressorOutputStream) new CompressorStreamFactory()
                .createCompressorOutputStream(CompressorStreamFactory.GZIP,os);

        new Thread() {
            public void run()
            {
                try
                {
                    long fileSize = source.length();

                    while (fileSize > cis.getBytesRead())
                    {
                        Thread.sleep(1000);
                        System.out.println(cis.getBytesRead() / (fileSize / 100.0));
                    }
                }
                catch (Exception ex)
                {
                    ex.printStackTrace();
                }
            }
        }.start();

        IOUtils.copy(cis,gzipOut);
    }

This works fine, but I need the thread, which is giving feedback about the progress not to be implemented in this method, but when calling it (in order to create something like a progressbar on an android device). So this is more like an architectural issue. Any ideas, on how to solve that?

Answer 1

I meanwhile solved it via overwriting the IOUtils.copy() by adding an interface as parameter:

public static long copy(final InputStream input, final OutputStream output, int buffersize,
        ProgressListener listener) throws IOException
{
    final byte[] buffer = new byte[buffersize];
    int n = 0;
    long count = 0;
    while (-1 != (n = input.read(buffer)))
    {
        output.write(buffer,0,n);
        count += n;
        listener.onProgress(n);
    }
    return count;
}

which is then called by something like this

copy(input, output, 4096, new ProgressListener() {

                long totalCounter = 0;

                DecimalFormat f = new DecimalFormat("#0.00");

                @Override
                public void onProgress(long bytesRead)
                {
                    totalCounter += bytesRead;
                    System.out.println(f.format(totalCounter / (fileSize / 100.0)));
                }
            });

The only thing, i am challenged by now, is to limit the output on the console not for each byte[4096] but for let's say each two megabyte. I tried something like this:

while (-1 != (n = input.read(buffer)))
    {
        output.write(buffer,0,n);
        count += n;
        while(n % 2097152 == 0)
        {
          listener.onProgress(n);
        }
    }
    return count;

But that does not give me any output at all