[Java加密算法]--base64加密的算法實作

base64加密應該是比較常用的算法，但是針對于不同版本的加密jar包，可能會有差異。

是以總結了幾種常用的方法，供參考：

1、自定義base64實作

package com.ngaa.bigdata.common.utils.algorithm;

import java.io.UnsupportedEncodingException;

public class Base64 {
   private static 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 };

   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();
   }

   public static byte[] decode(String str) throws UnsupportedEncodingException {
      StringBuffer sb = new StringBuffer();
      byte[] data = str.getBytes("US-ASCII");
      int len = data.length;
      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;
         sb.append((char) ((b1 << 2) | ((b2 & 0x30) >>> 4)));
         /* b3 */
         do {
            b3 = data[i++];
            if (b3 == 61)
               return sb.toString().getBytes("ISO-8859-1");
            b3 = base64DecodeChars[b3];
         } while (i < len && b3 == -1);
         if (b3 == -1)
            break;
         sb.append((char) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));
         /* b4 */
         do {
            b4 = data[i++];
            if (b4 == 61)
               return sb.toString().getBytes("ISO-8859-1");
            b4 = base64DecodeChars[b4];
         } while (i < len && b4 == -1);
         if (b4 == -1)
            break;
         sb.append((char) (((b3 & 0x03) << 6) | b4));
      }
      return sb.toString().getBytes("ISO-8859-1");
   }
}      

2、使用第三方依賴包實作

import org.apache.commons.codec.binary.Base64;

import java.io.UnsupportedEncodingException;

/**
 * Created by root on 20170907.
 * Update date:
 * Time: 11:26
 * Project: sparkmvn
 * Package: com.ngaa.scala.test
 * Describe :
 * Result of Test: test ok
 * Command:
 * Email:  [email protected]
 * Status：using online
 * <p>
 * Attention：
 */
public class TestBase64 {

    /**
     * base64 encoding
     * @param url string url
     * @return encoding str
     */
    public static String  str2base64String(String url) throws UnsupportedEncodingException {
        Base64 base64= new Base64();
        byte[] textByte= url.getBytes("UTF-8");
        String encodedText= base64.encodeToString(textByte);
        return encodedText;
    }
    /**
     *  base64 to String
     * @param base64Str base64 encoding str
     * @return common string
     */
    public static String base64ToString(String base64Str) throws UnsupportedEncodingException {
        Base64 base64= new Base64();
        return  new String(base64.decode(base64Str),"UTF-8");
    }

    public static void main(String[] args) {
        String url="http://www.baidu.com";
        try{
            //str to base64
            String base64Str=str2base64String(url);
            System.out.println("base64Str : "+base64Str);
            String base64Str02=com.ngaa.bigdata.common.utils.algorithm.Base64.encode(url.getBytes());
            System.out.println("base64Str : "+base64Str02);
            
            //base64 to str
            String str2base64=base64ToString(base64Str);
            System.out.println("str01 :"+str2base64);
            System.out.println("str02 :"+ com.ngaa.bigdata.common.utils.algorithm.Base64.decode(base64Str02));
        }catch (Exception e){
            e.printStackTrace();
        }
    }

}