Question

I have been given a task of copying data from a server. I am using BufferedInputStream and output stream to copy the data and I am doing it byte by byte. Even though it is running but It is taking ages to copy the data as some of them are in 100’s MBs, so definitely it is not gonna work. Can anyone suggest me any alternate of Byte by Byte copy so that my code can copy file that are in few Hundred MBs.
Buffer is 2048.

Here is how my code look like:

static void copyFiles(SmbFile[] files, String parent) throws IOException {

  SmbFileInputStream input = null;
  FileOutputStream output = null;
  BufferedInputStream buf_input = null;
  try {
    for (SmbFile f : files) {
      System.out.println("Working on files :" + f.getName());
      if (f.isDirectory()) {

        File folderToBeCreated = new File(parent+f.getName());
        if (!folderToBeCreated.exists()) {
          folderToBeCreated.mkdir();
          System.out.println("Folder name " + parent
                + f.getName() + "has been created");
        } else {
          System.out.println("exists");

        }

        copyFiles(f.listFiles(), parent +  f.getName());
      } else {

        input = (SmbFileInputStream) f.getInputStream();

        buf_input = new BufferedInputStream(input, BUFFER);

        File t = new File(parent + f.getName());
        if (!t.exists()) {
          t.createNewFile();
        }
        output = new FileOutputStream(t);

        int c;

        int count;
        byte data[] = new byte[BUFFER];

        while ((count = buf_input.read(data, 0, BUFFER)) != -1) {
          output.write(data, 0, count);
        }
      }
    }
  } catch (IOException e) {
    e.printStackTrace();

  } finally {
    if (input != null) {
      input.close();
    }
    if (output != null) {
      output.close();
    }
  }
}

Answer 1

Here is a link to an excellent post explaining how to use nio channels to make copies of streams. It introduces a helper method ChannelTools.fastChannelCopy that lets you copy streams like this:

final InputStream input = new FileInputStream(inputFile);
final OutputStream output = new FileOutputStream(outputFile);
final ReadableByteChannel inputChannel = Channels.newChannel(input);
final WriteableByteChannel outputChannel = Channels.newChannel(output);
ChannelTools.fastChannelCopy(inputChannel, outputChannel);
inputChannel.close();
outputChannel.close()