如何编码和解码base64字符串？

本文翻译自：How do I encode and decode a base64 string?

How do I return a base64 encoded string given a string? 给定字符串，如何返回以base64编码的字符串？
How do I decode a base64 encoded string into a string? 如何将base64编码的字符串解码为字符串？

#1楼

参考：https://stackoom.com/question/nGvo/如何编码和解码base-字符串

#2楼

Encode 编码

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

Decode 解码

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

#3楼

I'm sharing my implementation with some neat features: 我将通过一些简洁的功能分享我的实现：

uses Extension Methods for Encoding class. 使用扩展方法编码类。 Rationale is that someone may need to support different types of encodings (not only UTF8). 理由是有人可能需要支持不同类型的编码（不仅限于UTF8）。
Another improvement is failing gracefully with null result for null entry - it's very useful in real life scenarios and supports equivalence for X=decode(encode(X)). 另一个改进是由于空输入而导致的空结果优雅地失败了-这在现实生活中非常有用，并且支持X = decode（encode（X））的等效项。

Remark: Remember that to use Extension Method you have to (!) import the namespace with using keyword (in this case using MyApplication.Helpers.Encoding ). 备注：请记住，要使用扩展方法，您必须（！） using关键字（在这种情况下using MyApplication.Helpers.Encoding ）导入名称空间。

Code: 码：

namespace MyApplication.Helpers.Encoding
{public static class EncodingForBase64{public static string EncodeBase64(this System.Text.Encoding encoding, string text){if (text == null){return null;}byte[] textAsBytes = encoding.GetBytes(text);return System.Convert.ToBase64String(textAsBytes);}public static string DecodeBase64(this System.Text.Encoding encoding, string encodedText){if (encodedText == null){return null;}byte[] textAsBytes = System.Convert.FromBase64String(encodedText);return encoding.GetString(textAsBytes);}}
}

Usage example: 用法示例：

using MyApplication.Helpers.Encoding; // !!!namespace ConsoleApplication1
{class Program{static void Main(string[] args){Test1();Test2();}static void Test1(){string textEncoded = System.Text.Encoding.UTF8.EncodeBase64("test1...");System.Diagnostics.Debug.Assert(textEncoded == "dGVzdDEuLi4=");string textDecoded = System.Text.Encoding.UTF8.DecodeBase64(textEncoded);System.Diagnostics.Debug.Assert(textDecoded == "test1...");}static void Test2(){string textEncoded = System.Text.Encoding.UTF8.EncodeBase64(null);System.Diagnostics.Debug.Assert(textEncoded == null);string textDecoded = System.Text.Encoding.UTF8.DecodeBase64(textEncoded);System.Diagnostics.Debug.Assert(textDecoded == null);}}
}

#4楼

A slight variation on andrew.fox answer, as the string to decode might not be a correct base64 encoded string: andrew.fox答案略有不同，因为要解码的字符串可能不是正确的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;   }}}
}

#5楼

Based on the answers by Andrew Fox and Cebe, I turned it around and made them string extensions instead of Base64String extensions. 根据安德鲁·福克斯（Andrew Fox）和塞贝（Cebe）的回答，我把它改了一下，使它们成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;}}
}

#6楼

    using System;using System.Text;public static class Base64Conversions{public static string EncodeBase64(this string text, Encoding encoding = null){ if (text == null) return null;encoding = encoding ?? Encoding.UTF8;var bytes = encoding.GetBytes(text);return Convert.ToBase64String(bytes);}public static string DecodeBase64(this string encodedText, Encoding encoding = null){if (encodedText == null) return null;encoding = encoding ?? Encoding.UTF8;var bytes = Convert.FromBase64String(encodedText);return encoding.GetString(bytes);}}

Usage 用法

    var text = "Sample Text";var base64 = text.EncodeBase64();base64 = text.EncodeBase64(Encoding.UTF8); //or with Encoding