Base64Util

迷途d书童 发布于 2012/03/26 18:47
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package com.jh.jhcs.util;

import java.io.ByteArrayOutputStream;

public class Base64Util {
 private static final char[] base64EncodeChars = 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', '+', '/' };
 private static byte[] base64DecodeChars = new byte[] { -1, -1, -1, -1, -1,
   -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
   -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
   -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59,
   60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
   10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1,
   -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37,
   38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1,
   -1, -1 };

 private Base64Util() {
 }

 /**
  *
  * <code>encode</code>
  * @description: TODO(把字节数据变成字符)
  * @param data
  * @return
  * @since   2012-2-9    liaoyp
  */
 public static String encode(byte[] data) {
  StringBuffer sb = new StringBuffer();
  int len = data.length;
  int i = 0;
  int b1, b2, b3;
  while (i < len) {
   b1 = data[i++] & 0xff;
   if (i == len) {

    sb.append(base64EncodeChars[b1 >>> 2]);
    sb.append(base64EncodeChars[(b1 & 0x3) << 4]);

    sb.append("==");
    break;
   }
   b2 = data[i++] & 0xff;
   if (i == len) {
    sb.append(base64EncodeChars[b1 >>> 2]);
    sb.append(base64EncodeChars[((b1 & 0x03) << 4)
      | ((b2 & 0xf0) >>> 4)]);
    sb.append(base64EncodeChars[(b2 & 0x0f) << 2]);
    sb.append("=");
    break;
   }
   b3 = data[i++] & 0xff;
   sb.append(base64EncodeChars[b1 >>> 2]);
   sb.append(base64EncodeChars[((b1 & 0x03) << 4)
     | ((b2 & 0xf0) >>> 4)]);

   sb.append(base64EncodeChars[((b2 & 0x0f) << 2)
     | ((b3 & 0xc0) >>> 6)]);
   sb.append(base64EncodeChars[b3 & 0x3f]);
  }
  return sb.toString();
 }

 /**
  *
  * <code>decode</code>
  * @description: TODO(把字符变成字节数组)
  * @param str
  * @return
  * @since   2012-2-9    liaoyp
  */
 public static byte[] decode(String str) {
  byte[] data = str.getBytes();
  int len = data.length;
  ByteArrayOutputStream buf = new ByteArrayOutputStream(len);
  int i = 0;
  int b1, b2, b3, b4;
  while (i < len) { /* b1 */
   do {
    b1 = base64DecodeChars[data[i++]];
   } while (i < len && b1 == -1);
   if (b1 == -1) {
    break;
   } /* b2 */
   do {
    b2 = base64DecodeChars[data[i++]];
   } while (i < len && b2 == -1);
   if (b2 == -1) {
    break;
   }
   buf.write((int) ((b1 << 2) | ((b2 & 0x30) >>> 4))); /* b3 */
   do {
    b3 = data[i++];
    if (b3 == 61) {
     return buf.toByteArray();
    }
    b3 = base64DecodeChars[b3];
   } while (i < len && b3 == -1);
   if (b3 == -1) {
    break;
   }
   buf.write((int) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2))); /* b4 */
   do {
    b4 = data[i++];
    if (b4 == 61) {
     return buf.toByteArray();
    }
    b4 = base64DecodeChars[b4];
   } while (i < len && b4 == -1);
   if (b4 == -1) {
    break;
   }
   buf.write((int) (((b3 & 0x03) << 6) | b4));
  }
  return buf.toByteArray();
 }
   public static void main(String[] args) throws Exception { 
    System.out.println(encode("liao".getBytes()));
    System.out.println(new String(decode(encode("1".getBytes()))));
   }
}


原文链接:http://blog.csdn.net/liao3841054/article/details/7393723
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