private String getFileChecksum()
	throws IOException, NoSuchAlgorithmException
	{	InputStream in = new FileInputStream(file.getAbsolutePath());
		
		byte[] buffer = new byte[1024];
		int bytes_read;		

		MessageDigest complete = MessageDigest.getInstance("MD5");
		
		do
		{	bytes_read = in.read(buffer);
			if(bytes_read>0)
				complete.update(buffer, 0, bytes_read);
		}while(bytes_read!=-1);
		
		in.close();

		byte[] b = complete.digest();

		String result = "";
		for(int i = 0;i<b.length;i++)
			result += Integer.toString( (b[i]&0xff) + 0x100, 16).substring(1);
		
		return result;
	}