转java base64编码的加密和解密 转自：冷月的博客
java 加密算法 base64
（一）java自带的加密和解密
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); }}