代碼如下：

string url = "http://www.abc.com/這里是中文測試參數(shù)";

// 方式一
// 編碼 http%3a%2f%2fwww.abc.com%2f%e8%bf%99%e9%87%8c%e6%98%af%e4%b8%ad%e6%96%87%e6%b5%8b%e8%af%95%e5%8f%82%e6%95%b0
string urlEncode = System.Web.HttpUtility.UrlEncode(url);

// 解碼
string urlDecode = System.Web.HttpUtility.UrlDecode(urlEncode);

// 編碼時指定編碼
System.Web.HttpUtility.UrlEncode(url, System.Text.Encoding.UTF8);
System.Web.HttpUtility.UrlEncode(url, System.Text.Encoding.Unicode);
System.Web.HttpUtility.UrlEncode(url, System.Text.Encoding.GetEncoding("GB2312"));

// 解碼時指定編碼
System.Web.HttpUtility.UrlDecode(url, System.Text.Encoding.UTF8);
System.Web.HttpUtility.UrlDecode(url, System.Text.Encoding.Unicode);
System.Web.HttpUtility.UrlDecode(url, System.Text.Encoding.GetEncoding("GB2312"));


// 方式二, 只能在在aspx, ashx, controller中使用
// 編碼 http%3a%2f%2fwww.abc.com%2f%e8%bf%99%e9%87%8c%e6%98%af%e4%b8%ad%e6%96%87%e6%b5%8b%e8%af%95%e5%8f%82%e6%95%b0
string urlEncode2 = System.Web.HttpContext.Current.Server.UrlEncode(url);

// 解碼
string urlDecode2 = System.Web.HttpUtility.UrlDecode(urlEncode);