C#中將中文字符轉換成url編碼

Encoding gb2312 = Encoding.GetEncoding("gb2312");
Encoding utf8 = Encoding.UTF8;
//首先用utf-8進行解碼
string key = HttpUtility.UrlDecode(oStr, utf8);
// 將已經解碼的字符再次進行編碼.
string encode = HttpUtility.UrlEncode(key, utf8).ToLower();