FavoritesManager.java

/*
 * Copyright 2012 jMethods, Inc. 
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.myjavaworld.jftp;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.List;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SealedObject;
import javax.crypto.spec.SecretKeySpec;

/**
 * A Class used to serialize/deserialize favourite FTP sites. This is the
 * central point that contains all the IO logic required to
 * retrieve/store/add/edit/delete favouritre FTP sites.
 * 
 * @author Sai Pullabhotla, psai [at] jMethods [dot] com
 * @version 2.0
 */
public class FavoritesManager {

	/**
	 * Serialized file that stores the favourite FTP sites.
	 */
	private static final File FAV_FILE = new File(JFTP.DATA_HOME,
			"favorites.ser");

	/**
	 * Returns the list of favourite FTP sites. The list is generated by reading
	 * the serialized file, <code>FAV_FILE</code>.
	 * 
	 * @return List of favourite FTP sites.
	 * @exception IOException
	 *                if an IO error occurs while reading the file
	 * @exception ClassNotFoundException
	 *                We should never get this exception. If we get this, it
	 *                means that the software is not installed correctly.
	 */
	public static List getFavorites() throws IOException,
			ClassNotFoundException, IllegalBlockSizeException,
			BadPaddingException {
		List favorites = new ArrayList();
		FileInputStream fin = null;
		ObjectInputStream in = null;
		try {
			checkFavFile();
			fin = new FileInputStream(FAV_FILE);
			if (fin.available() > 0) {
				in = new ObjectInputStream(fin);
				Object obj = in.readObject();
				if (obj instanceof List) {
					favorites = (List) obj;
					saveFavorites(favorites);
				} else {
					SealedObject so = (SealedObject) obj;
					favorites = (List) so
							.getObject(getCipher(Cipher.DECRYPT_MODE));
				}
			}
			return favorites;
		} finally {
			try {
				if (in != null) {
					in.close();
				}
			} catch (IOException exp) {
			}
			try {
				if (fin != null) {
					fin.close();
				}
			} catch (IOException exp) {
			}
			in = null;
			fin = null;
		}
	}

	/**
	 * Saves the given list of favourite FTP sites to the favorite file.
	 * 
	 * @param favorites
	 *            List of favorites to be searialized
	 * @exception IOException
	 *                if an IO error occurs
	 */
	public static void saveFavorites(List favorites) throws IOException,
			IllegalBlockSizeException {
		if (favorites == null) {
			favorites = new ArrayList();
		}
		checkDataHome();
		ObjectOutputStream out = null;
		try {
			out = new ObjectOutputStream(new FileOutputStream(FAV_FILE));
			Cipher cipher = getCipher(Cipher.ENCRYPT_MODE);
			if (cipher == null) {
				// We do not have AES provider. so just save the favorites
				// unencrypted.
				out.writeObject(favorites);
			} else {
				SealedObject so = new SealedObject((Serializable) favorites,
						cipher);
				out.writeObject(so);
			}
		} finally {
			if (out != null) {
				out.close();
			}
			out = null;
		}
	}

	/**
	 * Adds the given favourite to the list of previously stored favorites and
	 * saves them back to the favorites file.
	 * 
	 * @param host
	 *            Favorite FTP site
	 * @exception IOException
	 *                if an IO error occurs
	 * @exception ClassNotFoundException
	 */
	public static void addFavorite(RemoteHost host) throws IOException,
			ClassNotFoundException, IllegalBlockSizeException,
			BadPaddingException {
		List favorites = getFavorites();
		favorites.add(host);
		saveFavorites(favorites);
	}

	private static void checkDataHome() {
		if (!JFTP.DATA_HOME.exists() || !JFTP.DATA_HOME.isDirectory()) {
			JFTP.DATA_HOME.mkdirs();
		}
	}

	private static void checkFavFile() throws IOException {
		checkDataHome();
		if (!FAV_FILE.exists() || !FAV_FILE.isFile()) {
			FAV_FILE.createNewFile();
		}
	}

	private static Cipher getCipher(int mode) {
		final byte[] encodedKey = { 28, -9, -23, 35, -93, -47, -28, 55, -83,
				-82, 101, -79, 36, 59, 77, -121 };
		Cipher cipher = null;
		try {
			cipher = Cipher.getInstance("AES");
			SecretKeySpec spec = new SecretKeySpec(encodedKey, "AES");
			cipher.init(mode, spec);
			return cipher;
		} catch (InvalidKeyException exp) {
			exp.printStackTrace();
		} catch (NoSuchAlgorithmException exp) {
			exp.printStackTrace();
		} catch (NoSuchPaddingException exp) {
			exp.printStackTrace();
		}
		return null;
	}
}