FileUtils.java

/**
 *  Copyright 2011 Oliver Buchtala
 *
 *	This file is part of ndogen.
 *
 *  ndogen is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  ndogen is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with ndogen.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.ndogen.watch;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class FileUtils {
	
	public static String readFile(String file) throws IOException {
		int len = (int) (new File(file)).length();
		FileInputStream fis = new FileInputStream(file);
		byte buf[] = new byte[len];
		fis.read(buf);
		fis.close();

		return new String(buf);
	}

	public static String getFileHash(File file) throws IOException {
		MessageDigest md;
		try {
			md = MessageDigest.getInstance("MD5");
		} catch (NoSuchAlgorithmException e) {
			throw new RuntimeException(e);
		}
		InputStream is = new FileInputStream(file);
		byte[] buf = new byte[1024];
		try {
		  is = new DigestInputStream(is, md);
		  // read stream to EOF as normal...
		  while(is.read(buf) > 0);
		}
		finally {
		  is.close();
		}
		byte[] digest = md.digest();
		return new String(digest);
	}

	public static String getMD5(String s) throws NoSuchAlgorithmException {
		byte[] bytes = s.getBytes();
		MessageDigest algorithm = MessageDigest.getInstance("MD5");
		algorithm.reset();
		algorithm.update(bytes);
		byte messageDigest[] = algorithm.digest();
	            
		StringBuffer hexString = new StringBuffer();
		for (int i=0;i<messageDigest.length;i++) {
			hexString.append(Integer.toHexString(0xFF & messageDigest[i]));
		}
		return hexString.toString();
	}
	
	public static boolean exists(String file) {
		return new File(file).exists();
	}
}