//将byte[]转换为16进制字符串

public static String byte2hex(byte[] b) {

    StringBuilder hs = new StringBuilder();
    String stmp;
    for (int n = 0; b != null && n < b.length; n++) {
        stmp = Integer.toHexString(b[n] & 0XFF);
        if (stmp.length() == 1)
            hs.append('0');
        hs.append(stmp);
    }
    return hs.toString().toUpperCase();
}

//将16进制字符串转换为byte[]
public static byte[] toBytes(String str) {
    if(str == null || str.trim().equals("")) {
        return new byte[0];
    }

    byte[] bytes = new byte[str.length() / 2];
    for(int i = 0; i < str.length() / 2; i++) {
        String subStr = str.substring(i * 2, i * 2 + 2);
        bytes[i] = (byte) Integer.parseInt(subStr, 16);
    }

    return bytes;
}

参考：https://blog.csdn.net/worm0527/article/details/69939307