java 串口通讯获取检验码

/**
 * 获取校验码
 * crc16 X16+x15+x2+1
 * 16进制报文是 02 03 00 00 00 40 CRC16
 * 传输的str：“020300000040”
 * 结果：4409
 * @param str
 * @return
 */
public static String getCRC(String str) {
    byte[] bytes = NumberUtils.hexStringToBytes(str);
    int CRC = 0x0000ffff;
    int POLYNOMIAL = 0x0000a001;

    int i, j;
    for (i = 0; i < bytes.length; i++) {
        CRC ^= ((int) bytes[i] & 0x000000ff);
        for (j = 0; j < 8; j++) {
            if ((CRC & 0x00000001) != 0) {
                CRC >>= 1;
                CRC ^= POLYNOMIAL;
            } else {
                CRC >>= 1;
            }
        }
    }
    String crc = Integer.toHexString(CRC);
    if (crc.length() == 2) {
        crc = "00" + crc;
    } else if (crc.length() == 3) {
        crc = "0" + crc;
    }
    crc = crc.substring(2, 4) + crc.substring(0, 2);
    return crc.toUpperCase();
}
public static void main(String[] args) {
    System.out.println(isNumber("0.1"));
    System.out.println(getCRC("FF0611030004"));
}