物理传输速度Java IO

Question

Is there a way to see the transfer speed (MB/s) while copying files? This is not for network sockets but for hdd to hdd for example. i copy the files content in bytes. Code for copying files: platform is windows

while ((length = in.read(buffer)) > 0) {
    out.write(buffer, 0, length);
    totalBytesCopied += length;
    int totalKilos = (int) totalBytesCopied / 1024;
    int totalMegas = totalKilos / 1024;
}

A example of how this can be done? Kind Regards

Answer 1

A kind of. First you can do it at application level. Your code that copies file should look like:

    byte[] buffer = new byte[BUFFER_SIZE];
    int n = 0;
    while (-1 != (n = input.read(buffer))) {
        output.write(buffer, 0, n);
    }

So, modify it as following:

    byte[] buffer = new byte[BUFFER_SIZE];
    int n = 0;
    long before = System.currentTimeMillis();
    while (-1 != (n = input.read(buffer))) {
        output.write(buffer, 0, n);
        long after = System.currentTimeMillis();
        double speed = n / (after - before) * 1000; // speed in byte per second 
        before = System.currentTimeMillis();
    }

You can do better. Implement SpeedMeasurementOutputStream that wraps any output stream and performs similar logic into its write() method. Then wrap FileOutputStream using this stream and get the speed while copying. This approach is better because this way you can measure speed of any stream.