java中 Hex(十六進制)和byte[]相互轉換

1.Hex轉成byte[]

    /**
     * hex轉byte數組
     * @param hex
     * @return
     */
    public static byte[] hexToByte(String hex){
        int m = 0, n = 0;
        int byteLen = hex.length() / 2; // 每兩個字符描述一個字節
        byte[] ret = new byte[byteLen];
        for (int i = 0; i < byteLen; i++) {
            m = i * 2 + 1;
            n = m + 1;
            int intVal = Integer.decode("0x" + hex.substring(i * 2, m) + hex.substring(m, n));
            ret[i] = Byte.valueOf((byte)intVal);
        }
        return ret;
    }

2.byte[]轉Hex

    /**
     * byte數組轉hex
     * @param bytes
     * @return
     */
    public static String byteToHex(byte[] bytes){
        String strHex = "";
        StringBuilder sb = new StringBuilder("");
        for (int n = 0; n < bytes.length; n++) {
            strHex = Integer.toHexString(bytes[n] & 0xFF);
            sb.append((strHex.length() == 1) ? "0" + strHex : strHex); // 每個字節由兩個字符表示，位數不夠，高位補0
        }
        return sb.toString().trim();
    }