Base 64编码用C＃实现

Encoder source

using System;namespace TestBase64{  /// <summary>  /// Summary description for Base64Encoder.  /// </summary>  public class Base64Encoder  {    byte[] source;    int length,length2;    int blockCount;    int paddingCount;    public Base64Encoder(byte[] input)    {      source=input;      length=input.Length;      if((length % 3)==0)      {        paddingCount=0;        blockCount=length/3;      }      else      {        paddingCount=3-(length % 3);//need to add padding        blockCount=(length+paddingCount) / 3;      }      length2=length+paddingCount;//or blockCount *3    }    public char[] GetEncoded()    {      byte[] source2;      source2=new byte[length2];      //copy data over insert padding      for (int x=0; x<length2;x++)      {        if (x<length)        {          source2[x]=source[x];        }        else        {          source2[x]=0;        }      }            byte b1, b2, b3;      byte temp, temp1, temp2, temp3, temp4;      byte[] buffer=new byte[blockCount*4];      char[] result=new char[blockCount*4];      for (int x=0;x<blockCount;x++)      {        b1=source2[x*3];        b2=source2[x*3+1];        b3=source2[x*3+2];        temp1=(byte)((b1 & 252)>>2);//first        temp=(byte)((b1 & 3)<<4);        temp2=(byte)((b2 & 240)>>4);        temp2+=temp; //second        temp=(byte)((b2 & 15)<<2);        temp3=(byte)((b3 & 192)>>6);        temp3+=temp; //third        temp4=(byte)(b3 & 63); //fourth        buffer[x*4]=temp1;        buffer[x*4+1]=temp2;        buffer[x*4+2]=temp3;        buffer[x*4+3]=temp4;      }      for (int x=0; x<blockCount*4;x++)      {        result[x]=sixbit2char(buffer[x]);      }      //covert last "A"s to "=", based on paddingCount      switch (paddingCount)      {        case 0:break;        case 1:result[blockCount*4-1]='=';break;        case 2:result[blockCount*4-1]='=';          result[blockCount*4-2]='=';          break;        default:break;      }      return result;    }    private char sixbit2char(byte b)    {      char[] lookupTable=new char[64]          {  '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','+','/'};      if((b>=0) &&(b<=63))      {        return lookupTable[(int)b];      }      else      {        //should not happen;        return ' ';      }    }  }}

Decoder source

using System;namespace TestBase64{  /// <summary>  /// Summary description for Base64Decoder.  /// </summary>  public class Base64Decoder  {    char[] source;    int length, length2, length3;    int blockCount;    int paddingCount;    public Base64Decoder(char[] input)    {      int temp=0;      source=input;      length=input.Length;      //find how many padding are there      for (int x=0;x<2;x++)      {        if(input[length-x-1]=='=')          temp++;      }      paddingCount=temp;      //calculate the blockCount;      //assuming all whitespace and carriage returns/newline were removed.      blockCount=length/4;      length2=blockCount*3;    }    public byte[] GetDecoded()    {      byte[] buffer=new byte[length];//first conversion result      byte[] buffer2=new byte[length2];//decoded array with padding      for(int x=0;x<length;x++)      {        buffer[x]=char2sixbit(source[x]);      }      byte b, b1,b2,b3;      byte temp1, temp2, temp3, temp4;      for(int x=0;x<blockCount;x++)      {        temp1=buffer[x*4];        temp2=buffer[x*4+1];        temp3=buffer[x*4+2];        temp4=buffer[x*4+3];                b=(byte)(temp1<<2);        b1=(byte)((temp2 & 48)>>4);        b1+=b;        b=(byte)((temp2 & 15)<<4);        b2=(byte)((temp3 & 60)>>2);        b2+=b;        b=(byte)((temp3 & 3)<<6);        b3=temp4;        b3+=b;        buffer2[x*3]=b1;        buffer2[x*3+1]=b2;        buffer2[x*3+2]=b3;      }      //remove paddings      length3=length2-paddingCount;      byte[] result=new byte[length3];      for(int x=0;x<length3;x++)      {        result[x]=buffer2[x];      }      return result;    }    private byte char2sixbit(char c)    {      char[] lookupTable=new char[64]          {      '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','+','/'};      if(c=='=')        return 0;      else      {        for (int x=0;x<64;x++)        {          if (lookupTable[x]==c)            return (byte)x;        }        //should not reach here        return 0;      }    }  }}