C# 获取url中的查询字符串参数

/// <summary>
/// 获取url中的查询字符串参数
/// </summary>
public static NameValueCollection ExtractQueryParams(string url)
{
    int startIndex = url.IndexOf("?");
    NameValueCollection values = new NameValueCollection();
 
    if (startIndex <= 0)
        return values;
 
    string[] nameValues = url.Substring(startIndex + 1).Split('&');
 
    foreach (string s in nameValues)
    {
        string[] pair = s.Split('=');
 
        string name = pair[0];
        string value = string.Empty;
 
        if (pair.Length > 1)
            value = pair[1];
 
        values.Add(name, value);
    }
 
    return values;
}

///   <summary>
///  解码URL.
///   </summary>
///   <param name="encoding"> null为自动选择编码 </param>
///   <param name="str"></param>
///   <returns></returns>
public   static   string  MyUrlDeCode( string  str, Encoding encoding)
{
     if  (encoding  ==   null )
    {
        Encoding utf8  =  Encoding.UTF8;
         // 首先用utf-8进行解码                     
         string  code  =  HttpUtility.UrlDecode(str.ToUpper(), utf8);
         // 将已经解码的字符再次进行编码.
         string  encode  =  HttpUtility.UrlEncode(code, utf8).ToUpper();
         if  (str  ==  encode)
            encoding  =  Encoding.UTF8;
         else
            encoding  =  Encoding.GetEncoding( " gb2312 " );
    }
     return  HttpUtility.UrlDecode(str, encoding);
}

using System.Security.Cryptography;
using System.Collections.Specialized;

NameValueCollection col = ExtractQueryParams("partnerId=12546&action=getProduct&timestamp=1560850762&nonce=8ObVcFPmverVgKth&sign=ea93f793f67e3a442fd8ad2bdf61e70e&data=FxsFyiX2s7M3zsnRzpkvGe6oOeLvmN1Q0u24cC1YX3PBU8fE9KA%2BOwU2RFD%2F4yhglONDiFC3te5Cqe0%2FLrfkZQcsUefPieWWo8K2GlOAA4OQBu3Y9YX8xkWTNPPcWjHLN%2BMd%2BOR%2B6fHL0AxQgKBNdTSKdOR9fo9WUZa1Snvh%2Bww%3D");
            string searchKey = col["action"];
            Response.Write(searchKey);