用Base64加解密时发现的问题（其实时java基础问题byte[]转String）

今天用Base64进行加解密发现 能加密哪是解密总是一堆看不懂的东西：

原文：zhouzhou

密文：V8y2RvWHiNE2Z/6GxyDLiA==

解密得到明文：[B@73035e27

项目时间比较紧，就是不知道怎么回事，急的不行不行的。

最后发现问题时byte[]转String的问题。

所以写了一个byte[]转String的测试：

如下：

byte []b = new byte[]{'h','y','e','n','h'};

System.out.println(b); //System.out.println(b.toString()); 也是不行的。

打印为：[B@73035e27

byte []b = new byte[]{'z','h','o','u','z','h','o','u'};

System.out.println(new String(b));

打印为：zhouzhou

所以byte[]转String时用 new String(b);

ps：Base64的工具网上有很多 一般的字符串在结尾会带上“＝”号等特殊符号。有时候不利于在网络中传输 可能会出错。下面贴出一个改进的Base64算法：

public final class Base64 {

privatestatic finalint BASELENGTH = 128;

privatestatic finalint LOOKUPLENGTH = 64;

privatestatic finalint TWENTYFOURBITGROUP = 24;

privatestatic finalint EIGHTBIT = 8;

privatestatic finalint SIXTEENBIT = 16;

privatestatic finalint FOURBYTE = 4;

privatestatic finalint SIGN = -128;

privatestatic charPAD = '=';

privatestatic byte[]base64Alphabet =new byte[BASELENGTH];

privatestatic char[] lookUpBase64Alphabet =new char[LOOKUPLENGTH];

static {

for (inti = 0; i < BASELENGTH; ++i) {

base64Alphabet[i] = -1;

}

for (inti = 'Z'; i >= 'A'; i--) {

base64Alphabet[i] = (byte) (i -'A');

}

for (inti = 'z'; i >= 'a'; i--) {

base64Alphabet[i] = (byte) (i -'a' + 26);

}

for (inti = '9'; i >= '0'; i--) {

base64Alphabet[i] = (byte) (i -'0' + 52);

}

base64Alphabet['+'] = 62;

base64Alphabet['/'] = 63;

for (inti = 0; i <= 25;i++) {

lookUpBase64Alphabet[i] = (char) ('A' + i);

}

for (inti = 26, j = 0;i <= 51; i++,j++) {

lookUpBase64Alphabet[i] = (char) ('a' + j);

}

for (inti = 52, j = 0;i <= 61; i++,j++) {

lookUpBase64Alphabet[i] = (char) ('0' + j);

}

lookUpBase64Alphabet[62] = (char)'+';

lookUpBase64Alphabet[63] = (char)'/';

}

privatestatic boolean isWhiteSpace(charoctect) {

return (octect == 0x20 ||octect == 0xd || octect == 0xa ||octect == 0x9);

}

privatestatic boolean isPad(charoctect) {

return (octect ==PAD);

}

privatestatic boolean isData(charoctect) {

return (octect <BASELENGTH && base64Alphabet[octect] != -1);

}

/**

* Encodes hex octects into Base64

* 

* @param binaryData

*            Array containing binaryData

* @return Encoded Base64 array

*/

public static String encode(byte[] binaryData) {

if (binaryData ==null) {

returnnull;

}

intlengthDataBits = binaryData.length *EIGHTBIT;

if (lengthDataBits == 0) {

return"";

}

intfewerThan24bits = lengthDataBits %TWENTYFOURBITGROUP;

intnumberTriplets = lengthDataBits /TWENTYFOURBITGROUP;

intnumberQuartet = fewerThan24bits != 0 ?numberTriplets + 1 : numberTriplets;

charencodedData[] = null;

encodedData =new char[numberQuartet * 4];

byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;

intencodedIndex = 0;

intdataIndex = 0;

for (inti = 0; i < numberTriplets; i++) {

b1 =binaryData[dataIndex++];

b2 =binaryData[dataIndex++];

b3 =binaryData[dataIndex++];

l = (byte) (b2 & 0x0f);

k = (byte) (b1 & 0x03);

byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);

byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);

byte val3 = ((b3 & SIGN) == 0) ? (byte) (b3 >> 6) : (byte) ((b3) >> 6 ^ 0xfc);

encodedData[encodedIndex++] =lookUpBase64Alphabet[val1];

encodedData[encodedIndex++] =lookUpBase64Alphabet[val2 | (k << 4)];

encodedData[encodedIndex++] =lookUpBase64Alphabet[(l << 2) |val3];

encodedData[encodedIndex++] =lookUpBase64Alphabet[b3 & 0x3f];

}

// form integral number of 6-bit groups

if (fewerThan24bits ==EIGHTBIT) {

b1 =binaryData[dataIndex];

k = (byte) (b1 & 0x03);

byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);

encodedData[encodedIndex++] =lookUpBase64Alphabet[val1];

encodedData[encodedIndex++] =lookUpBase64Alphabet[k << 4];

encodedData[encodedIndex++] =PAD;

encodedData[encodedIndex++] =PAD;

} elseif (fewerThan24bits ==SIXTEENBIT) {

b1 =binaryData[dataIndex];

b2 =binaryData[dataIndex + 1];

l = (byte) (b2 & 0x0f);

k = (byte) (b1 & 0x03);

byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);

byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);

encodedData[encodedIndex++] =lookUpBase64Alphabet[val1];

encodedData[encodedIndex++] =lookUpBase64Alphabet[val2 | (k << 4)];

encodedData[encodedIndex++] =lookUpBase64Alphabet[l << 2];

encodedData[encodedIndex++] =PAD;

}

return new String(encodedData);

}

/**

* Decodes Base64 data into octects

* 

* @param encoded

*            string containing Base64 data

* @return Arraycontainind decoded data.

*/

public static byte[] decode(String encoded) {

if (encoded ==null) {

returnnull;

}

char[] base64Data = encoded.toCharArray();

// remove white spaces

int len = removeWhiteSpace(base64Data);

if (len %FOURBYTE != 0) {

returnnull;// should be divisible by four

}

intnumberQuadruple = (len /FOURBYTE);

if (numberQuadruple == 0) {

returnnew byte[0];

}

bytedecodedData[] = null;

byte b1 = 0, b2 = 0, b3 = 0, b4 = 0;

char d1 = 0, d2 = 0, d3 = 0, d4 = 0;

int i = 0;

intencodedIndex = 0;

intdataIndex = 0;

decodedData =new byte[(numberQuadruple) * 3];

for (; i < numberQuadruple - 1; i++) {

if (!isData((d1 =base64Data[dataIndex++])) || !isData((d2 =base64Data[dataIndex++]))

|| !isData((d3 =base64Data[dataIndex++])) || !isData((d4 =base64Data[dataIndex++]))) {

returnnull;

} // if found "no data" just return null

b1 =base64Alphabet[d1];

b2 =base64Alphabet[d2];

b3 =base64Alphabet[d3];

b4 =base64Alphabet[d4];

decodedData[encodedIndex++] = (byte) (b1 << 2 |b2 >> 4);

decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));

decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);

}

if (!isData((d1 =base64Data[dataIndex++])) || !isData((d2 =base64Data[dataIndex++]))) {

returnnull;// if found "no data" just return null

}

b1 =base64Alphabet[d1];

b2 =base64Alphabet[d2];

d3 =base64Data[dataIndex++];

d4 =base64Data[dataIndex++];

if (!isData((d3)) || !isData((d4))) {// Check if they are PAD characters

if (isPad(d3) && isPad(d4)) {

if ((b2 & 0xf) != 0)// last 4 bits should be zero

{

returnnull;

}

byte[] tmp = new byte[i * 3 + 1];

System.arraycopy(decodedData, 0,tmp, 0, i * 3);

tmp[encodedIndex] = (byte) (b1 << 2 |b2 >> 4);

return tmp;

} else if (!isPad(d3) && isPad(d4)) {

b3 =base64Alphabet[d3];

if ((b3 & 0x3) != 0)// last 2 bits should be zero

{

returnnull;

}

byte[] tmp = new byte[i * 3 + 2];

System.arraycopy(decodedData, 0,tmp, 0, i * 3);

tmp[encodedIndex++] = (byte) (b1 << 2 |b2 >> 4);

tmp[encodedIndex] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));

return tmp;

} else {

returnnull;

}

} else {// No PAD e.g 3cQl

b3 =base64Alphabet[d3];

b4 =base64Alphabet[d4];

decodedData[encodedIndex++] = (byte) (b1 << 2 |b2 >> 4);

decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));

decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);

}

returndecodedData;

}

/**

* remove WhiteSpace from MIME containing encoded Base64 data.

* 

* @param data

*            the byte array of base64 data (with WS)

* @return the new length

*/

private static int removeWhiteSpace(char[]data) {

if (data ==null) {

return 0;

}

// count characters that's not whitespace

int newSize = 0;

int len = data.length;

for (inti = 0; i < len; i++) {

if (!isWhiteSpace(data[i])) {

data[newSize++] =data[i];

}

}

returnnewSize;

}

}