JAvaはフォルダの下のすべてのファイルのコピーを実現します

ソースフォルダのすべてのファイルを含むフォルダ、ファイルフォルダのコピーを実現する実用的なクラスを退屈に書きました.

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Reader;
import java.io.Writer;

public class Util {
	public static int buffer_size = 2048;

	private static void doCopy(File src, File dst) {
		if (src.isFile()) {
			try {
				copyFile(src, dst);

			} catch (IOException e) {
				e.printStackTrace();
			}
		} else {
			File dir = copyDirectory(src, dst);
			File[] files = src.listFiles();
			if (files.length == 0) {

			} else {
				for (File file : files) {
					doCopy(file, dir);
				}
			}
		}
	}

	public static void copy(File src, File dst) throws IOException {
		if (!src.exists() || !dst.exists())
			throw new FileNotFoundException();
		else if (src.isFile() && dst.isFile())
			copy(new FileReader(src), new FileWriter(dst));
		else if (src.isDirectory() && (!dst.isDirectory()))
			throw new IllegalArgumentException("Destination should be a directory!");
		else {
			doCopy(src, dst);
		}
		
	}

	private static void copyFile(File src, File dst) throws IOException {
		File file = new File(dst, src.getName());
		copy(new FileReader(src), new FileWriter(file));
	}

	private static File copyDirectory(File src, File dst) {
		File file = new File(dst, src.getName());
		file.mkdir();
		return file;
	}

	private static int copy(Reader in, Writer out) throws IOException {
		int byteCount = 0;
		try {
			int bytesReader = -1;
			char[] buffer = new char[buffer_size];

			while ((bytesReader = in.read(buffer)) != -1) {
				out.write(buffer, 0, bytesReader);
				byteCount += bytesReader;
			}
			out.flush();
		} finally {
			in.close();
			out.close();
		}
		return byteCount;
	}

}