Center the text in whole page

My try:

\documentclass{scrartcl}
\begin{document}
\
\vfil
\hfil Centered text \hfil
\vfil
\end{document}

You can use \vspace command as it follows :

\documentclass{book}
\begin{document}

\begin{center}
\vspace*{\stretch{1}}
Your text centered
\vspace*{\stretch{1}}
\end{center}

\clearpage    

\end{document}

It works without text before and the text centered can be as long as possible (one page). \stretch makes nice effects.

\documentclass{article}
\usepackage[paper=a6paper]{geometry}% Just for this example
\pagestyle{empty}% Just for this example

\begin{document}
\vspace*{\fill}% * is needed here
\noindent
\makebox[\textwidth]{\Huge SoMeTHiNG}

\vfill
\end{document}