vggbmmm 校驗和算法 modbus CRC16 校驗 BCD碼轉爲10進制串 彙總備忘

import java.text.SimpleDateFormat;
import java.util.Calendar;

class Tools {

    /**
     * vggbmmm 校驗和算法
     * 
     * @src 校驗字符串首地址
     * @sizes 總字節數
     * @return 一個字節的校驗和
     */
    public static char checkSum(Byte[] rc_data) {
        int sum = 0;
        char ret = 0;
        if (rc_data != null) {
            for (int i = 0; i < rc_data.length; i++) {
                sum += (char) rc_data[i].byteValue();
            }

        }
        ret = (char) (sum & 0xff);
        return ret;
    }
    //多態
    public static char checkSum(byte[] rc_data) {
        int sum = 0;
        char ret = 0;
        if (rc_data != null) {
            for (int i = 0; i < rc_data.length; i++) {
                sum += (char) rc_data[i];
            }

        }
        ret = (char) (sum & 0xff);
        return ret;
    }


    
    private final static char[] hexArray = "0123456789abcdef".toCharArray();

    // 字節數組轉字符串 效率高
    public static String byteArrToHex(byte... bytes) {
        char[] hexChars = new char[bytes.length * 2];
        for (int j = 0; j < bytes.length; j++) {
            int v = bytes[j] & 0xFF;
            hexChars[j * 2] = hexArray[v >>> 4];
            hexChars[j * 2 + 1] = hexArray[v & 0x0F];
        }
        return new String(hexChars);
    }

    // 字節數據轉字符串 通用，效率低
    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);
            if (hv.length() < 2) {
                stringBuilder.append(0);
            }
            stringBuilder.append(hv);
        }
        return stringBuilder.toString();
    }

    // modbus CRC16 校驗
    public static String getCRC(byte[] bytes) {
        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;
                }
            }
        }
        CRC = ((CRC & 0xFF00) >> 8) | ((CRC & 0x00FF) << 8);// 高低位轉換
        // 補全4位
        return String.format("%04x", CRC);
    }

    // 16進制字符串轉字節數組
    public static byte[] hexStringToByte(String hex) {
        int len = (hex.length() / 2);
        byte[] result = new byte[len];
        char[] achar = hex.toCharArray();
        for (int i = 0; i < len; i++) {
            int pos = i * 2;
            result[i] = (byte) (toByte(achar[pos]) << 4 | toByte(achar[pos + 1]));
        }
        return result;
    }
    
    /**
    * @功能: BCD碼轉爲10進制串(阿拉伯數據)
    * @參數: BCD碼
    * @結果: 10進制串
    */
   public static String bcd2Str(byte[] bytes) {
       StringBuffer temp = new StringBuffer(bytes.length * 2);
       for (int i = 0; i < bytes.length; i++) {
           temp.append((byte) ((bytes[i] & 0xf0) >>> 4));
           temp.append((byte) (bytes[i] & 0x0f));
       }
       return temp.toString().substring(0, 1).equalsIgnoreCase("0") ? temp
               .toString().substring(1) : temp.toString();
   }

   //byte 數組與 int 的相互轉換
	public static int byteArrayToInt(byte[] b) {
	    return   b[3] & 0xFF |
	            (b[2] & 0xFF) << 8 |
	            (b[1] & 0xFF) << 16 |
	            (b[0] & 0xFF) << 24;
	}

    private static int toByte(char c) {
        byte b = (byte) "0123456789abcdef".indexOf(c);
        return b;
    }

}