How to typeset Chinese font appropriately: \usepackage{xeCJK} give Chinese as mess code

I asked a question about typesetting a few Chinese characters in a new page in a report. This problem seems to have been solved by gusbrs and egreg. However, when I use exactly the answers both give me mess code as follows. Thus, I believe now my problem becomes how to use Chinese font appropriately in Latex?

\documentclass[12pt,a4paper,twoside]{report}

\usepackage{xeCJK}
\usepackage{bm}
\usepackage{lmodern}%for quote page
\newlength\longest

\begin{document}
\clearpage
\thispagestyle{empty}
\null\vfill

\settowidth\longest{\huge 我正在认真学习的中文。}
\centering
\parbox{\longest}{%
\raggedright{\huge%
我正在认真学习的中文。\\
北京；\\
彩虹；\\
柔中带刚。   \par\bigskip
}
\raggedleft\Large 《语文$\bm{\cdot}$长城》 \par%
}

\vfill\vfill

\clearpage

\end{document}