C#的base64编码、解码函数

C#的base64编码、解码函数

http://hi.baidu.com/xiaohei_accp/item/275c71460fb5ca35fb896035

/// <summary>

///Base64 编码/解码

/// </summary>

public class Base64

{

/// <summary>

/// Base64编码

/// </summary>

/// <param name="Message"></param>

/// <returns></returns>

public static string Base64Encode(string Message)

{

char[] Base64Code = new char[]{'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T',

'U','V','W','X','Y','Z','a','b','c','d','e','f','g','h','i','j','k','l','m','n',

'o','p','q','r','s','t','u','v','w','x','y','z','0','1','2','3','4','5','6','7',

'8','9','+','/','='};

byte empty = (byte)0;

System.Collections.ArrayList byteMessage = new System.Collections.ArrayList(System.Text.Encoding.Default.GetBytes(Message));

System.Text.StringBuilder outmessage;

int messageLen = byteMessage.Count;

int page = messageLen / 3;

int use = 0;

if ((use = messageLen % 3) > 0)

{

for (int i = 0; i < 3 - use; i++)

byteMessage.Add(empty);

page++;

}

outmessage = new System.Text.StringBuilder(page * 4);

for (int i = 0; i < page; i++)

{

byte[] instr = new byte[3];

instr[0] = (byte)byteMessage[i * 3];

instr[1] = (byte)byteMessage[i * 3 + 1];

instr[2] = (byte)byteMessage[i * 3 + 2];

int[] outstr = new int[4];

outstr[0] = instr[0] >> 2;

outstr[1] = ((instr[0] & 0x03) << 4) ^ (instr[1] >> 4);

if (!instr[1].Equals(empty))

outstr[2] = ((instr[1] & 0x0f) << 2) ^ (instr[2] >> 6);

else

outstr[2] = 64;

if (!instr[2].Equals(empty))

outstr[3] = (instr[2] & 0x3f);

else

outstr[3] = 64;

outmessage.Append(Base64Code[outstr[0]]);

outmessage.Append(Base64Code[outstr[1]]);

outmessage.Append(Base64Code[outstr[2]]);

outmessage.Append(Base64Code[outstr[3]]);

}

return outmessage.ToString();

}

/// <summary>

/// Base64解码

/// </summary>

/// <param name="Message"></param>

/// <returns></returns>

public static string Base64Decode(string Message)

{

if ((Message.Length % 4) != 0)

{

throw new ArgumentException("不是正确的BASE64编码，请检查。", "Message");

}

if (!System.Text.RegularExpressions.Regex.IsMatch(Message, "^[A-Z0-9/+=]*$", System.Text.RegularExpressions.RegexOptions.IgnoreCase))

{

throw new ArgumentException("包含不正确的BASE64编码，请检查。", "Message");

}

string Base64Code = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

int page = Message.Length / 4;

System.Collections.ArrayList outMessage = new System.Collections.ArrayList(page * 3);

char[] message = Message.ToCharArray();

for (int i = 0; i < page; i++)

{

byte[] instr = new byte[4];

instr[0] = (byte)Base64Code.IndexOf(message[i * 4]);

instr[1] = (byte)Base64Code.IndexOf(message[i * 4 + 1]);

instr[2] = (byte)Base64Code.IndexOf(message[i * 4 + 2]);

instr[3] = (byte)Base64Code.IndexOf(message[i * 4 + 3]);

byte[] outstr = new byte[3];

outstr[0] = (byte)((instr[0] << 2) ^ ((instr[1] & 0x30) >> 4));

if (instr[2] != 64)

{

outstr[1] = (byte)((instr[1] << 4) ^ ((instr[2] & 0x3c) >> 2));

}

else

{

outstr[2] = 0;

}

if (instr[3] != 64)

{

outstr[2] = (byte)((instr[2] << 6) ^ instr[3]);

}

else

{

outstr[2] = 0;

}

outMessage.Add(outstr[0]);

if (outstr[1] != 0)

outMessage.Add(outstr[1]);

if (outstr[2] != 0)

outMessage.Add(outstr[2]);

}

byte[] outbyte = (byte[])outMessage.ToArray(Type.GetType("System.Byte"));

return System.Text.Encoding.Default.GetString(outbyte);

}

}

=========================================C#自带有Base64编码、解码方法======================================

Console.WriteLine(Convert.ToBase64String(System.Text.Encoding.Default.GetBytes("木子屋-http://www.mzwu.com/")));//编码

Console.WriteLine(System.Text.Encoding.Default.GetString(Convert.FromBase64String("xL7X087dLWh0dHA6Ly93d3cubXp3dS5jb20v ")));//解码