通用工具类-Base64Encoder加密

public class Base64Encoder {
 private static final char last2byte = (char) Integer
   .parseInt("00000011", 2);
 private static final char last4byte = (char) Integer
   .parseInt("00001111", 2);
 private static final char last6byte = (char) Integer
   .parseInt("00111111", 2);
 private static final char lead6byte = (char) Integer
   .parseInt("11111100", 2);
 private static final char lead4byte = (char) Integer
   .parseInt("11110000", 2);
 private static final char lead2byte = (char) Integer
   .parseInt("11000000", 2);
 private static final char[] encodeTable = 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', '+', '/' };
 /**
  * Base64 encoding.
  * @param from The src data.
  * @return
  */
 public static String encode(byte[] from) {
  StringBuffer to = new StringBuffer((int) (from.length * 1.34) + 3);
  int num = 0;
  char currentByte = 0;
  for (int i = 0; i < from.length; i++) {
   num = num % 8;
   while (num < 8) {
    switch (num) {
    case 0:
     currentByte = (char) (from[i] & lead6byte);
     currentByte = (char) (currentByte >>> 2);
     break;
    case 2:
     currentByte = (char) (from[i] & last6byte);
     break;
    case 4:
     currentByte = (char) (from[i] & last4byte);
     currentByte = (char) (currentByte << 2);
     if ((i + 1) < from.length) {
      currentByte |= (from[i + 1] & lead2byte) >>> 6;
     }
     break;
    case 6:
     currentByte = (char) (from[i] & last2byte);
     currentByte = (char) (currentByte << 4);
     if ((i + 1) < from.length) {
      currentByte |= (from[i + 1] & lead4byte) >>> 4;
     }
     break;
    }
    to.append(encodeTable[currentByte]);
    num += 6;
   }
  }
  if (to.length() % 4 != 0) {
   for (int i = 4 - to.length() % 4; i > 0; i--) {
    to.append("=");
   }
  }
  return to.toString();
 }
}