如何检查字符串是否 html 编码？

Question

I am working with my web API. Some user send parameter string as HTML encoded I want to identify the coming parameters are HTML encoded or plain text.

My Web API method is

public HttpResponseMessage Get(string Accesskey, string AccessPwd)
{
   // code logic
}

i am getting Accesskey as Html Encoded like

Accesskey="AbIfZVn4y514sJbt%2BCCMJy6lsmsMi6uOWyhUhynDSf1MEqZ%2FWJnwUuCFO8zMFa4jCRWQrXHKdBaHd9CCdDNfoKDnPg1W9No16JQbL2DBEGg%3D";

i want output like

Accesskey="AbIfZVn4y514sJbt+CCMJy6lsmsMi6uOWyhUhynDSf1MEqZ/WJnwUuCFO8zMFa4jCRWQrXHKdBaHd9CCdDNfoKDnPg1W9No16JQbL2DBEGg="

Answer 1

A technique should be to force URL decoding and check if result is the same as source string.

using System;
using System.Web;

var incomingStrings = new[] { "not encoded", "encodéd" };

foreach (var incomingString in incomingStrings)
{
    Console.WriteLine(IsUrlEncoded(incomingString));
}

private bool IsUrlEncoded(string source)
{
    return source != HttpUtility.UrlDecode(source);
}

Answer 2

You can just use

console.log('yourtext');

It will show as original in console.

Answer 3

I got this problem as well. My text value is not always encoded HTML, it can be just encoded text. When I use a method like

HttpUtility.HtmlDecode(value)

it always return the same text, not decoded. So it is not work for me.

To resolve it, I used a rough way by checking if the string is typically an encoded text.

        if (!string.IsNullOrEmpty(value) && value.Length % 4 == 0 && !value.Contains(" ") && !value.Contains("\t") && !value.Contains("\r") && !value.Contains("\n"))
        {
            // it's encoded text value
        }

• Encoded text's length is always multiple of 4.
• Encoded text always never has any space.
• Encoded text always never has any tab or newline character.