字符串和byte[]的转换

    public static String bytesToHexString(byte[] src){
        StringBuilder stringBuilder = new StringBuilder("");
        if (src == null || src.length <= 0) {
            return null;
        }
        for (int i = 0; i < src.length; i++) {
            int v = src[i] & 0xFF;
            String hv = Integer.toHexString(v).toUpperCase();
            if (hv.length() < 2) {
                stringBuilder.append(0);
            }
            stringBuilder.append(hv);
        }
        return stringBuilder.toString();
    }
    //这个是为了转15693的数据专用的，略去第一个字符，接下来中间每5个字符取后面4个字符，然后将其转为字符串
    //为了存储用
    public static String bytesToHexString1(byte[] src){
        StringBuilder stringBuilder = new StringBuilder("");
        if (src == null || src.length <= 0) {
            return null;
        }
        for (int i = 2; i < src.length; i++) {
            if(((i-1) % 5 == 0) && (i > 2))
                continue;
            int v = src[i] & 0xFF;
            String hv = Integer.toHexString(v).toUpperCase();
            if (hv.length() < 2) {
                stringBuilder.append(0);
            }
            stringBuilder.append(hv);
        }
        return stringBuilder.toString();
    }
    //这个是为了转15693的数据专用的，略去第一个字符，接下来中间每5个字符取后面4个字符，然后将其转为字符串
    //为了显示用
    public static String bytesToHexString2(byte[] src){
        StringBuilder stringBuilder = new StringBuilder("");
        if (src == null || src.length <= 0) {
            return null;
        }
        for (int i = 2; i < src.length; i++) {
            if(((i-1) % 5 == 0) && (i > 2))
                continue;
            int v = src[i] & 0xFF;
            String hv = Integer.toHexString(v).toUpperCase();
            if (hv.length() < 2) {
                stringBuilder.append(0);
            }
            stringBuilder.append(hv + " ");
        }
        return stringBuilder.toString();
    }

    /**
     * Convert hex string to byte[]
     * @param hexString the hex string
     * @return byte[]
     */
    public static byte[] hexStringToBytes(String hexString) {
        if (hexString == null || hexString.equals("")) {
            return null;
        }
        hexString = hexString.toUpperCase();
        int length = hexString.length() / 2;
        char[] hexChars = hexString.toCharArray();
        byte[] d = new byte[length];
        for (int i = 0; i < length; i++) {
            int pos = i * 2;
            d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));
        }
        return d;
    }
    /**
     * Convert char to byte
     * @param c char
     * @return byte
     */
    public static byte charToByte(char c) {
        return (byte) "0123456789ABCDEF".indexOf(c);
    }