asp.net替换和恢复html特殊字符

/// <summary>
/// 替换html中的特殊字符
/// </summary>
/// <param name="theString">需要进行替换的文本。</param>
/// <returns>替换完的文本。</returns>
public string HtmlEncode(string theString)
{
     theString=theString.Replace(">", ">");
     theString=theString.Replace("<", "<");
     theString=theString.Replace("  ", "  ");
     theString=theString.Replace("  ", "  ");
     theString=theString.Replace("\"", """);
     theString=theString.Replace("\'", "'");
     theString=theString.Replace("\n", "<br/> ");
     return theString;
}

/// <summary>
/// 恢复html中的特殊字符
/// </summary>
/// <param name="theString">需要恢复的文本。</param>
/// <returns>恢复好的文本。</returns>
public string HtmlDiscode(string theString)
{
     theString=theString.Replace(">", ">");
     theString=theString.Replace("<", "<");
     theString=theString.Replace(" "," ");
     theString=theString.Replace("  ","  ");
     theString=theString.Replace(""","\"");
     theString=theString.Replace("'","\'");
     theString=theString.Replace("<br/> ","\n");
     return theString;
}