import java.io.ByteArrayOutputStream;

/**

* 表单传输信息加密

* @author wutz

*

*/

public class Base64Util {

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 };

/**

* 解密

* @param str

* @return

*/

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) {

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;

}

buf.write((int) ((b1 << 2) | ((b2 & 0x30) >>> 4)));

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)));

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();

}

/**

* 返回解密结果

*/

public static String decodeToString(String param){

return new String(decode(param));

}

}