Base64OutputStream.java

package URLConnectionTest;

import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
This stream filter converts a stream of bytes to their
Base64 encoding.

Base64 encoding encodes 3 bytes into 4 characters.
|11111122|22223333|33444444|
Each set of 6 bits is encoded according to the
toBase64 map. If the number of input bytes is not
a multiple of 3, then the last group of 4 characters
is padded with one or two = signs. Each output line
is at most 76 characters.
*/
class Base64OutputStream extends FilterOutputStream
{
/**
   Constructs the stream filter
   @param out the stream to filter
*/
public Base64OutputStream(OutputStream out)
{  
   super(out);
}

public void write(int c) throws IOException
{  
   inbuf[i] = c;
   i++;
   if (i == 3)
   {  
      super.write(toBase64[(inbuf[0] & 0xFC) >> 2]);
      super.write(toBase64[((inbuf[0] & 0x03) << 4) |
         ((inbuf[1] & 0xF0) >> 4)]);
      super.write(toBase64[((inbuf[1] & 0x0F) << 2) |
         ((inbuf[2] & 0xC0) >> 6)]);
      super.write(toBase64[inbuf[2] & 0x3F]);
      col += 4;
      i = 0;
      if (col >= 76)
      {  
         super.write('\n');
         col = 0;
      }
   }
}

public void flush() throws IOException
{  
   if (i == 1)
   {  
      super.write(toBase64[(inbuf[0] & 0xFC) >> 2]);
      super.write(toBase64[(inbuf[0] & 0x03) << 4]);
      super.write('=');
      super.write('=');
   }
   else if (i == 2)
   {  
      super.write(toBase64[(inbuf[0] & 0xFC) >> 2]);
      super.write(toBase64[((inbuf[0] & 0x03) << 4) |
         ((inbuf[1] & 0xF0) >> 4)]);
      super.write(toBase64[(inbuf[1] & 0x0F) << 2]);
      super.write('=');
   }
}

private static char[] toBase64 =
{  
   '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', '+', '/'
};

private int col = 0;
private int i = 0;
private int[] inbuf = new int[3];
}