FileHelper.java

package com.malcom.library.android.utils.encoding.base64;

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.text.MessageFormat;

/**
 * Utilities for File manipulation. More information about this class is
 * available from <a target="_top" href=
 * "http://ostermiller.org/utils/FileHelper.html">ostermiller.org</a>.
 * 
 * @author Stephen Ostermiller
 *         http://ostermiller.org/contact.pl?regarding=Java+Utilities
 * @since ostermillerutils 1.00.00
 */
public class FileHelper
{

	/**
	 * Move a file from one location to another. An attempt is made to rename
	 * the file and if that fails, the file is copied and the old file deleted.
	 * 
	 * If the destination file already exists, an exception will be thrown.
	 * 
	 * @param from
	 *            file which should be moved.
	 * @param to
	 *            desired destination of the file.
	 * @throws IOException
	 *             if an error occurs.
	 * 
	 * @since ostermillerutils 1.00.00
	 */
	public static void move(File from, File to) throws IOException
	{
		move(from, to, false);
	}

	/**
	 * Move a file from one location to another. An attempt is made to rename
	 * the file and if that fails, the file is copied and the old file deleted.
	 * 
	 * @param from
	 *            file which should be moved.
	 * @param to
	 *            desired destination of the file.
	 * @param overwrite
	 *            If false, an exception will be thrown rather than overwrite a
	 *            file.
	 * @throws IOException
	 *             if an error occurs.
	 * 
	 * @since ostermillerutils 1.00.00
	 */
	public static void move(File from, File to, boolean overwrite) throws IOException
	{
		if (to.exists())
		{
			if (overwrite)
			{
				if (!to.delete())
				{
					throw new IOException(MessageFormat.format("deleteerror %s", (Object[]) new String[]
					{ to.toString() }));
				}
			} else
			{
				throw new IOException(MessageFormat.format("alreadyexistserror %s", (Object[]) new String[]
				{ to.toString() }));
			}
		}

		if (from.renameTo(to))
			return;

		InputStream in = null;
		OutputStream out = null;
		try
		{
			in = new FileInputStream(from);
			out = new FileOutputStream(to);
			copy(in, out);
			in.close();
			in = null;
			out.flush();
			out.close();
			out = null;
			if (!from.delete())
			{
				throw new IOException(MessageFormat.format("deleteoriginalerror %s", (Object[]) new String[]
				{ from.toString(), to.toString() }));
			}
		} finally
		{
			if (in != null)
			{
				in.close();
				in = null;
			}
			if (out != null)
			{
				out.flush();
				out.close();
				out = null;
			}
		}
	}

	/**
	 * Buffer size when reading from input stream.
	 * 
	 * @since ostermillerutils 1.00.00
	 */
	private final static int BUFFER_SIZE = 1024;

	/**
	 * Copy the data from the input stream to the output stream.
	 * 
	 * @param in
	 *            data source
	 * @param out
	 *            data destination
	 * @throws IOException
	 *             in an input or output error occurs
	 * 
	 * @since ostermillerutils 1.00.00
	 */
	private static void copy(InputStream in, OutputStream out) throws IOException
	{
		byte[] buffer = new byte[BUFFER_SIZE];
		int read;
		while ((read = in.read(buffer)) != -1)
		{
			out.write(buffer, 0, read);
		}
	}
}