c# url自动解码解决方案

 1 public static NameValueCollection GetQueryString(string queryString, Encoding encoding)
 2         {
 3             queryString = queryString.Replace("?", "");
 4             NameValueCollection result = new NameValueCollection(StringComparer.OrdinalIgnoreCase);
 5             if (!string.IsNullOrEmpty(queryString))
 6             {
 7                 int count = queryString.Length;
 8                 for (int i = 0; i < count; i++)
 9                 {
10                     int startIndex = i;
11                     int index = -1;
12                     while (i < count)
13                     {
14                         char item = queryString[i];
15                         if (item == ‘=‘)
16                         {
17                             if (index < 0)
18                             {
19                                 index = i;
20                             }
21                         }
22                         else if (item == ‘&‘)
23                         {
24                             break;
25                         }
26                         i++;
27                     }
28                     string key = null;
29                     string value = null;
30                     if (index >= 0)
31                     {
32                         key = queryString.Substring(startIndex, index - startIndex);
33                         value = queryString.Substring(index + 1, (i - index) - 1);
34                     }
35                     else
36                     {
37                         key = queryString.Substring(startIndex, i - startIndex);
38                     }
39 
40                     result[key] = HttpUtility.UrlDecode(value, encoding);
41 
42                     if ((i == (count - 1)) && (queryString[i] == ‘&‘))
43                     {
44                         result[key] = string.Empty;
45                     }
46                 }
47             }
48             return result;
49         }
50 
51 　　　　 NameValueCollection col = GetQueryString(Request.Url.Query, Encoding.GetEncoding("GB2312"));
52         string user_id = col["user_name"];