1、使用UrlEncode和UrlDecode编解码

#if !NETSTANDARD
using System.Web;
#else
using System.Net;
#endif
using System;
namespace UrlHelper
{
	public class UrlHelper
	{

		protected string UrlEncode(string value)
		{
			var tmp = value;
#if !NETSTANDARD
			return HttpUtility.UrlEncode(tmp, System.Text.Encoding.GetEncoding("utf-8"));
#else
			return WebUtility.UrlEncode(tmp);
#endif
		}
		public static string UrlDecode(string value)
		{
			var tmp = value;
#if !NETSTANDARD
			return HttpUtility.UrlDecode(tmp);
#else
			return WebUtility.UrlDecode(tmp);
#endif
		}
	}
}

2、使用HtmlEncode和HtmlDecode编解码

using System;
using System.Net;
#if !NETSTANDARD
using System.Web;
#else
#endif
namespace HtmlHelpler
{
	public class HtmlHelpler
	{
		public static string HtmlDecode(string value)
		{
			var tmp = value;
#if !NETSTANDARD
			return HttpUtility.HtmlDecode(tmp);
#else
			return WebUtility.HtmlDecode(tmp);
#endif
		}
		public static string HtmlEncode(string value)
		{
			var tmp = value;
#if !NETSTANDARD
			return HttpUtility.HtmlEncode(tmp);
#else
			return WebUtility.HtmlEncode(tmp);
#endif
		}
	}
}

相关文档：ASP.NET Core(.NET Core)中使用UrlDecode和UrlEncode方法