转自http://www.cnblogs.com/jyshi/archive/2011/08/09/2132762.html ；
/// <summary>
/// 转换纯文本内容为 HTML 内容
/// </summary>
/// <param name="Text">纯文本内容</param>
/// <returns>转换后的 HTML 内容</returns>
public static string ToHTML(string Text)
{
return Regex.Replace(Regex.Replace(Regex.Replace(Regex.Replace(Regex.Replace("<p>" + Text + "</p>", "\r\n", "</p><p>"), "\r", "</p><p>"), "\n", "<br />"), "\t", " "), " ", " ");
}
/// <summary>
/// 转换 Html 内容为纯文本内容
/// </summary>
/// <param name="HTML">HTML 内容</param>
/// <returns>转换后的纯文本内容</returns>
public static string ToText(string HTML)
{
string input = HTML;
return Regex.Replace(Regex.Replace(Regex.Replace(Regex.Replace(Regex.Replace(Regex.Replace(input, @"(?m)<script[^>]*>(\w|\W)*?</script[^>]*>", "", RegexOptions.Multiline | RegexOptions.IgnoreCase), @"(?m)<style[^>]*>(\w|\W)*?</style[^>]*>", "", RegexOptions.Multiline | RegexOptions.IgnoreCase), @"(?m)<select[^>]*>(\w|\W)*?</select[^>]*>", "", RegexOptions.Multiline | RegexOptions.IgnoreCase), @"(?m)<a[^>]*>(\w|\W)*?</a[^>]*>", "", RegexOptions.Multiline | RegexOptions.IgnoreCase), "(<[^>]+?>)| ", "", RegexOptions.Multiline | RegexOptions.IgnoreCase), @"(\s)+", "", RegexOptions.Multiline | RegexOptions.IgnoreCase);
}