NioDemo.java

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// Demo of using the java.nio package.
// This application copies a file, efficiently.
// (Note the buffer size chosen;  If you know your operating
// system's block (or "cluster") size, using that will be the
// most efficient.
//
// Written 1/2009 by Wayne Pollock, Tampa Florida USA

import java.io.*;
import java.nio.*;
import java.nio.channels.*;

public class NioDemo
{
   private static final int BUF_SIZE = 4096;
   public static void main ( String [] args ) throws Exception
   {
      if ( args.length != 2 )
      {  System.err.println( "Usage: NioDemo inputFile outputFile" );
         return;
      }

      FileInputStream fin = new FileInputStream( args[0] );
      FileChannel cin = fin.getChannel();
      FileOutputStream fout = new FileOutputStream( args[1] );
      FileChannel cout = fout.getChannel();

      ByteBuffer buf = ByteBuffer.allocate( BUF_SIZE );

      System.out.print( "Copying \"" + args[0] + "\" to \""
         + args[1] + "\":." );

      buf.clear();
      while ( cin.read(buf) != -1 ) {
         System.out.print( "." );
         buf.flip();
         cout.write(buf);
         buf.clear();
      }

      System.out.println( "Done!" );

      fin.close(); fout.close();
   }
}