C＃-解码字符串不会返回原始编码的字符串

Question

I have a random generated string that I need to put it in a URL, so I encode it like this:

var encodedToken = System.Web.HttpUtility.UrlEncode(token, System.Text.Encoding.UTF8);

In an ASP.NET action method, I receive this token and decode it:

var token = System.Web.HttpUtility.UrlDecode(encodedToken, System.Text.Encoding.UTF8);

but these tokens are not the same. For example the ab+cd string would encode to ab%2bcd and decoding the result would give me the ab cd string (the plus character changed to whitespace).

So far I have only noticed the + character problem, there may be others.

How can I solve this issue?

Answer 1

In your context, it appears that you don't need to call UrlDecode (since %2b decodes to + and + decodes to a blank space - ie you have double decoded).

Given, the framework appears to have already decoded it for you, you may remove your use of UrlDecode .

Answer 2

According to the Microsoft documentation:

You can encode a URL using with the UrlEncode method or the UrlPathEncode method. However, the methods return different results. The UrlEncode method converts each space character to a plus character (+). The UrlPathEncode method converts each space character into the string "%20", which represents a space in hexadecimal notation. Use the UrlPathEncode method when you encode the path portion of a URL in order to guarantee a consistent decoded URL, regardless of which platform or browser performs the decoding.

https://docs.microsoft.com/en-us/dotnet/api/system.web.httputility.urlencode?view=netframework-4.7.2