另一种写法:
private string Encode64(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 &#61; 0; i < 3 - use; i&#43;&#43;)
byteMessage.Add(empty);
page&#43;&#43;;
}
outmessage &#61; new System.Text.StringBuilder(page * 4);
for (int i &#61; 0; i < page; i&#43;&#43;)
{
byte[] instr &#61; new byte[3];
instr[0] &#61; (byte)byteMessage[i * 3];
instr[1] &#61; (byte)byteMessage[i * 3 &#43; 1];
instr[2] &#61; (byte)byteMessage[i * 3 &#43; 2];
int[] outstr &#61; new int[4];
outstr[0] &#61; instr[0] >> 2;
outstr[1] &#61; ((instr[0] & 0x03) << 4) ^ (instr[1] >> 4);
if (!instr[1].Equals(empty))
outstr[2] &#61; ((instr[1] & 0x0f) << 2) ^ (instr[2] >> 6);
else
outstr[2] &#61; 64;
if (!instr[2].Equals(empty))
outstr[3] &#61; (instr[2] & 0x3f);
else
outstr[3] &#61; 64;
outmessage.Append(Base64Code[outstr[0]]);
outmessage.Append(Base64Code[outstr[1]]);
outmessage.Append(Base64Code[outstr[2]]);
outmessage.Append(Base64Code[outstr[3]]);
}
return outmessage.ToString();
}
private string Decode64(string Message)
{
string Base64Code &#61; "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789&#43;/&#61;";
int page &#61; Message.Length / 4;
System.Collections.ArrayList outMessage &#61; new System.Collections.ArrayList(page * 3);
char[]message &#61; Message.ToCharArray();
for (int i &#61; 0; i < page; i&#43;&#43;)
{
byte[]instr &#61; new byte[4];
instr[0] &#61; (byte)Base64Code.IndexOf(message[i * 4]);
instr[1] &#61; (byte)Base64Code.IndexOf(message[i * 4&#43;1]);
instr[2] &#61; (byte)Base64Code.IndexOf(message[i * 4&#43;2]);
instr[3] &#61; (byte)Base64Code.IndexOf(message[i * 4&#43;3]);
byte[]outstr &#61; new byte[3];
outstr[0] &#61; (byte)((instr[0] << 2) ^ ((instr[1] & 0x30) >> 4));
if (instr[2] !&#61; 64)
{
outstr[1] &#61; (byte)((instr[1] << 4) ^ ((instr[2] & 0x3c) >> 2));
}
else
{
outstr[2] &#61; 0;
}
if (instr[3] !&#61; 64)
{
outstr[2] &#61; (byte)((instr[2] << 6) ^ instr[3]);
}
else
{
outstr[2] &#61; 0;
}
outMessage.Add(outstr[0]);
if (outstr[1] !&#61; 0)
outMessage.Add(outstr[1]);
if (outstr[2] !&#61; 0)
outMessage.Add(outstr[2]);
}
byte[]outbyte &#61; (byte[])outMessage.ToArray(Type.GetType("System.Byte"));
return System.Text.Encoding.Default.GetString(outbyte);
}
{
char[] Base64Code &#61; new char[]
{
&#39;A&#39;, &#39;B&#39;, &#39;C&#39;, &#39;D&#39;, &#39;E&#39;, &#39;F&#39;, &#39;G&#39;, &#39;H&#39;, &#39;I&#39;, &#39;J&#39;, &#39;K&#39;, &#39;L&#39;, &#39;M&#39;, &#39;N&#39;,
&#39;O&#39;, &#39;P&#39;, &#39;Q&#39;, &#39;R&#39;, &#39;S&#39;, &#39;T&#39;, &#39;U&#39;, &#39;V&#39;, &#39;W&#39;, &#39;X&#39;, &#39;Y&#39;, &#39;Z&#39;, &#39;a&#39;, &#39;b&#39;,
&#39;c&#39;, &#39;d&#39;, &#39;e&#39;, &#39;f&#39;, &#39;g&#39;, &#39;h&#39;, &#39;i&#39;, &#39;j&#39;, &#39;k&#39;, &#39;l&#39;, &#39;m&#39;, &#39;n&#39;, &#39;o&#39;, &#39;p&#39;,
&#39;q&#39;, &#39;r&#39;, &#39;s&#39;, &#39;t&#39;, &#39;u&#39;, &#39;v&#39;, &#39;w&#39;, &#39;x&#39;, &#39;y&#39;, &#39;z&#39;, &#39;0&#39;, &#39;1&#39;, &#39;2&#39;, &#39;3&#39;,
&#39;4&#39;, &#39;5&#39;, &#39;6&#39;, &#39;7&#39;, &#39;8&#39;, &#39;9&#39;, &#39;&#43;&#39;, &#39;/&#39;, &#39;&#61;&#39;
};
byte empty &#61; (byte)0;
System.Collections.ArrayList byteMessage &#61; new
System.Collections.ArrayList(System.Text.Encoding.Default.GetBytes
(Message));
System.Text.StringBuilder outmessage;
int messageLen &#61; byteMessage.Count;
int page &#61; messageLen / 3;
int use &#61; 0;
if ((use &#61; messageLen % 3) > 0)
{
for (int i &#61; 0; i < 3 - use; i&#43;&#43;)
byteMessage.Add(empty);
page&#43;&#43;;
}
outmessage &#61; new System.Text.StringBuilder(page * 4);
for (int i &#61; 0; i < page; i&#43;&#43;)
{
byte[] instr &#61; new byte[3];
instr[0] &#61; (byte)byteMessage[i * 3];
instr[1] &#61; (byte)byteMessage[i * 3 &#43; 1];
instr[2] &#61; (byte)byteMessage[i * 3 &#43; 2];
int[] outstr &#61; new int[4];
outstr[0] &#61; instr[0] >> 2;
outstr[1] &#61; ((instr[0] & 0x03) << 4) ^ (instr[1] >> 4);
if (!instr[1].Equals(empty))
outstr[2] &#61; ((instr[1] & 0x0f) << 2) ^ (instr[2] >> 6);
else
outstr[2] &#61; 64;
if (!instr[2].Equals(empty))
outstr[3] &#61; (instr[2] & 0x3f);
else
outstr[3] &#61; 64;
outmessage.Append(Base64Code[outstr[0]]);
outmessage.Append(Base64Code[outstr[1]]);
outmessage.Append(Base64Code[outstr[2]]);
outmessage.Append(Base64Code[outstr[3]]);
}
return outmessage.ToString();
}
private string Decode64(string Message)
{
string Base64Code &#61; "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789&#43;/&#61;";
int page &#61; Message.Length / 4;
System.Collections.ArrayList outMessage &#61; new System.Collections.ArrayList(page * 3);
char[]message &#61; Message.ToCharArray();
for (int i &#61; 0; i < page; i&#43;&#43;)
{
byte[]instr &#61; new byte[4];
instr[0] &#61; (byte)Base64Code.IndexOf(message[i * 4]);
instr[1] &#61; (byte)Base64Code.IndexOf(message[i * 4&#43;1]);
instr[2] &#61; (byte)Base64Code.IndexOf(message[i * 4&#43;2]);
instr[3] &#61; (byte)Base64Code.IndexOf(message[i * 4&#43;3]);
byte[]outstr &#61; new byte[3];
outstr[0] &#61; (byte)((instr[0] << 2) ^ ((instr[1] & 0x30) >> 4));
if (instr[2] !&#61; 64)
{
outstr[1] &#61; (byte)((instr[1] << 4) ^ ((instr[2] & 0x3c) >> 2));
}
else
{
outstr[2] &#61; 0;
}
if (instr[3] !&#61; 64)
{
outstr[2] &#61; (byte)((instr[2] << 6) ^ instr[3]);
}
else
{
outstr[2] &#61; 0;
}
outMessage.Add(outstr[0]);
if (outstr[1] !&#61; 0)
outMessage.Add(outstr[1]);
if (outstr[2] !&#61; 0)
outMessage.Add(outstr[2]);
}
byte[]outbyte &#61; (byte[])outMessage.ToArray(Type.GetType("System.Byte"));
return System.Text.Encoding.Default.GetString(outbyte);
}