gistfile1.java

package de.michaelwellner.edu.file;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.channels.FileChannel;

public class FileUtil {

  private FileUtil() { }
	
	public static void copyFile(final File src, final File dst) throws IOException {
		copyBufferedStream(new FileInputStream(src), new FileOutputStream(dst));
	}
	
	public static void copyStreams(final InputStream in, final OutputStream out) throws IOException {
		int data = -1;
		while ((data = in.read()) != -1) {
			out.write(data);
		}
		out.flush();
	}
	
	public static void copyBufferedStream(final InputStream in, final OutputStream out) throws IOException {
		
		final InputStream bin = new BufferedInputStream(in);
		final OutputStream bout = new BufferedOutputStream(out);
		
		copyStreams(bin, bout);
		
	}
	
	public static boolean directoryExists(final File directoryToCheck) {
		if (directoryToCheck == null) return false;
		
		return directoryToCheck.exists() && directoryToCheck.isDirectory();
	}
	
	public static String[] getContents(final File directoryToCheck) {
		if (directoryExists(directoryToCheck)) {
			final String[] contents = directoryToCheck.list();
			if (contents != null) return contents;
		}
		
		return new String[0];
	}
	
	public static void copyViaChannel(final File src, final File dst) throws IOException {
		FileChannel inChannel = new FileInputStream(src).getChannel();
		FileChannel outChannel = new FileInputStream(dst).getChannel();
		
		outChannel.transferFrom(inChannel, 0, inChannel.size());
		
		inChannel.close();
		outChannel.close();
	}
	
}