字节数组与16进制字符串互转

private static final int zero = java.lang.Math.abs(Byte.MIN_VALUE);
private static final byte[][] hexList = new byte[zero+Byte.MAX_VALUE+1][];
static{
for(int i=0; i<Byte.MAX_VALUE*2+2; i++){
byte b = (byte) (Byte.MIN_VALUE+i);
int num = (int)b;
if (num < 0) {
num = num + 256;
}
String sTemp = Integer.toHexString(num).toUpperCase();
if (sTemp.length() == 1) {
sTemp = "0" + sTemp;
}
hexList[b+zero] = sTemp.getBytes();
}
}

/**
* 将字节数组转化为一个16进制的字符串
*
* @param b 原始字节数组
*
* @return 16进制的字符串
*/
public static String getHexString(byte[] b) {
byte[] bytes = new byte[b.length*2];
for (int i = 0; i < b.length; i++) {
int offset = b[i]+zero;
bytes[i*2] = hexList[offset][0];
bytes[i*2+1] = hexList[offset][1];
}
return new String(bytes);
}

public static byte[] hex2Bytes(String s) throws IOException {
int i = s.length() / 2;
byte result[] = new byte[i];
int j = 0;
if (s.length() % 2 != 0){
throw new IOException("hexadecimal string with odd number of characters");
}
for (int k = 0; k < i; k++) {
char c = s.charAt(j++);
int l = "0123456789abcdef0123456789ABCDEF".indexOf(c);
if (l == -1){
throw new IOException("hexadecimal string contains non hex character");
}
int i1 = (l & 0xf) << 4;
c = s.charAt(j++);
l = "0123456789abcdef0123456789ABCDEF".indexOf(c);
i1 += l & 0xf;
result[k] = (byte) i1;
}
return result;
}