// Encoding
string passw = "tes123";
var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(passw);
string pass = System.Convert.ToBase64String(plainTextBytes);

// Normal
var encodedTextBytes = Convert.FromBase64String(pass);
string plainText = Encoding.UTF8.GetString(encodedTextBytes);

编码

public static string Base64Encode(string plainText) {
  var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(plainText);
  return System.Convert.ToBase64String(plainTextBytes);
}

解码

public static string Base64Decode(string base64EncodedData) {
  var base64EncodedBytes = System.Convert.FromBase64String(base64EncodedData);
  return System.Text.Encoding.UTF8.GetString(base64EncodedBytes);
}

根据Andrew Fox和Cebe的回答，我将其转换为字符串扩展，而不是Base64String扩展。

public static class StringExtensions
{
    public static string ToBase64(this string text)
    {
        return ToBase64(text, Encoding.UTF8);
    }

    public static string ToBase64(this string text, Encoding encoding)
    {
        if (string.IsNullOrEmpty(text))
        {
            return text;
        }

        byte[] textAsBytes = encoding.GetBytes(text);
        return Convert.ToBase64String(textAsBytes);
    }

    public static bool TryParseBase64(this string text, out string decodedText)
    {
        return TryParseBase64(text, Encoding.UTF8, out decodedText);
    }

    public static bool TryParseBase64(this string text, Encoding encoding, out string decodedText)
    {
        if (string.IsNullOrEmpty(text))
        {
            decodedText = text;
            return false;
        }

        try
        {
            byte[] textAsBytes = Convert.FromBase64String(text);
            decodedText = encoding.GetString(textAsBytes);
            return true;
        }
        catch (Exception)
        {
            decodedText = null;
            return false;
        }
    }
}

要在c#中将一个字符串编码为base64字符串，可以使用Convert。ToBase64String方法:

string originalString = "Hello World";
string encodedString = Convert.ToBase64String(Encoding.UTF8.GetBytes(originalString));

要在c#中将base64编码的字符串解码为字符串，可以使用Convert。FromBase64String方法:

string encodedString = "SGVsbG8gV29ybGQ=";
string originalString = Encoding.UTF8.GetString(Convert.FromBase64String(encodedString));

有点像安德鲁。Fox回答，因为要解码的字符串可能不是一个正确的base64编码的字符串:

using System;

namespace Service.Support
{
    public static class Base64
    {
        public static string ToBase64(this System.Text.Encoding encoding, string text)
        {
            if (text == null)
            {
                return null;
            }

            byte[] textAsBytes = encoding.GetBytes(text);
            return Convert.ToBase64String(textAsBytes);
        }

        public static bool TryParseBase64(this System.Text.Encoding encoding, string encodedText, out string decodedText)
        {
            if (encodedText == null)
            {
                decodedText = null;
                return false;
            }

            try
            {
                byte[] textAsBytes = Convert.FromBase64String(encodedText);
                decodedText = encoding.GetString(textAsBytes);
                return true;
            }
            catch (Exception)
            {
                decodedText = null;
                return false;   
            }
        }
    }
}

一行代码:

注意:使用System和System。文本指示。

编码:

string encodedStr = Convert.ToBase64String(Encoding.UTF8.GetBytes("inputStr"));

解码:

string inputStr = Encoding.UTF8.GetString(Convert.FromBase64String(encodedStr));