Base64算法相信大家都比较熟悉吧,dt.jar已经提拱了具体的实现细节。你可以查阅相关文档和源码,
package com.moxue.api;
import java.io.UnsupportedEncodingException;
public class CryptoUtil {
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};
// 编码
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();
}
// 解码
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("iso8859-1");
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("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");
}
}
这段代码可以也可以在Android客户端重用,Android端负责加密码,而XFire服务器端负责解密,这样做是为了安全性着想。