Base64封装类

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

/// <summary>
///Base64 的摘要说明
/// </summary>
public class Base64
{
public Base64()
{
//
//TODO: 在此处添加构造函数逻辑
//
}
public static 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 = 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();
}

public static string Decode64(string 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);
}
}