Question

When downloading a rar file from the internet with the code below, the downloaded file is larger than it actually is.
Not sure what causes this?

        bis = new BufferedInputStream(urlConn.getInputStream());
        bos = new BufferedOutputStream(new FileOutputStream(outputFile));

        eventBus.fireEvent(this, new DownloadStartedEvent(item));

        int read;
        byte[] buffer = new byte[2048];
        while ((read = bis.read(buffer)) != -1) {
            bos.write(buffer);
        }

        eventBus.fireEvent(this, new DownloadCompletedEvent(item));

Answer 1

You are writing a full buffer to the output with every write, even if the read(byte[]) operation didn’t completely fill it.

Also, since you are reading into a byte[] already, the buffered streams are just counter-productive overhead. Use buffered streams with the single-byte read() and write() methods.

Here is a better pattern to follow.

InputStream is = urlConn.getInputStream();
try {
  FileOutputStream os = new FileOutputStream(outputFile);
  try {
    byte[] buffer = new byte[2048];
    while (true) {
      int n = is.read(buffer);
      if (n < 0)
        break;
      os.write(buffer, 0, n);
    }
    os.flush();
  } finally {
    os.close();
  }
} finally {
  is.close();
}