java 加密算法 base64 以及 自定义 加解密

http://www.cnblogs.com/langtianya/archive/2012/09/18/2690864.html

import sun.misc.BASE64Decoder;

public class Base64Utils {

 

 public static String getBASE64(byte[] b) {

  String s = null;

  if (b != null) {

   s = new sun.misc.BASE64Encoder().encode(b);

  }

  return s;

 }

 

 public static byte[] getFromBASE64(String s) {

  byte[] b = null;

  if (s != null) {

   BASE64Decoder decoder = new BASE64Decoder();

   try {

    b = decoder.decodeBuffer(s);

    return b;

   } catch (Exception e) {

    e.printStackTrace();

   }

  }

  return b;

 }

}

（二）自己写加密算法

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) {

           

            do {

                b1 = base64DecodeChars[data[i++]];

            } while (i < len && b1 == -1);

            if (b1 == -1) break;

           

            do {

                b2 = base64DecodeChars

                        [data[i++]];

            } while (i < len && b2 == -1);

            if (b2 == -1) break;

            sb.append((char) ((b1 << 2) | ((b2 & 0x30) >>> 4)));

           

            do {

                b3 = data[i++];

                if (b3 == 61) return sb.toString().getBytes("iso8859-1");

                b3 = base64DecodeChars[b3];

            } while (i < len && b3 == -1);

            if (b3 == -1) break;

            sb.append((char) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));

           

            do {

                b4 = data[i++];

                if (b4 == 61) return sb.toString().getBytes("iso8859-1");

                b4 = base64DecodeChars[b4];

            } while (i < len && b4 == -1);

            if (b4 == -1) break;

            sb.append((char) (((b3 & 0x03) << 6) | b4));

        }

        return sb.toString().getBytes("iso8859-1");

    }

    public static void main(String[] args) throws UnsupportedEncodingException {

        String s = "abcd";

        System.out.println("加密前：" + s);

        String x = encode(s.getBytes());

        System.out.println("加密后：" + x);

        String x1 = new String(decode(x));

        System.out.println("解密后：" + x1);

    }

}