String topic = "/sys/"+productKey+"/"+deviceName+"/thing/file/upload/mqtt/init_reply";
airC.subscribe(topic);

topic = "/sys/"+productKey+"/"+deviceName+"/thing/file/upload/mqtt/send_reply";
airC.subscribe(topic);

topic = "/sys/"+productKey+"/"+deviceName+"/thing/file/upload/mqtt/init";
String payload = "{\"id\":\"123\",\"params\":{\"fileName\":\"a01.txt\",\"fileSize\":-1}}";
airC.publish(topic, false, payload);

if (topic.contains("/thing/file/upload/mqtt/init_reply")) {
  String content = new String((byte[]) aMessage.getData());
  JSONObject request = JSONObject.parseObject(content);

  System.out.println("content==="+content);

  JSONObject requestData = request.getJSONObject("data");
  String uploadId = requestData.getString("uploadId");

  if(uploadId == null){
    return;
  }

  AirC airC = new AirC ();

  String filepath = "D:\\a5.txt";
  File file = new File(filepath);
  long fileSize = file.length();

  topic = "/sys/"+productKey+"/"+deviceName+"/thing/file/upload/mqtt/send";
  String payload = "{\"id\":\"123\",\"params\":{\"uploadId\":\""+uploadId+"\",\"offset\":0,\"bSize\":"+fileSize+",\"isComplete\":true}}";

  System.out.println("payload==="+payload);

    //首部字段及报文格式                            | 文件分片           | 文件完整性检验算法
    //Header Length | Header String Bytes        | File Block Bytes  | CRC16/IBM
    // （2字节）     | （JSON String Bytes，n字节） | （n字节）          | （2字节）
  try {
    byte[] data = hexToByteArray( numToHex16(payload.length()));
    byte[] data1 = payload.getBytes("utf-8");
    byte[] data2 = getContent(filepath);
    byte[] data3 = CRC16Standard.getCRCBytes(data2);
    airC.publishBytes(topic,byteMergerAll(data, data1, data2, data3));
  } catch (UnsupportedEncodingException e) {
    e.printStackTrace();
  } catch (IOException e) {
    e.printStackTrace();
  }
}

//获取文件内容
public static byte[] getContent(String filePath) throws IOException {
  File file = new File(filePath);
  long fileSize = file.length();
  if (fileSize > Integer.MAX_VALUE) {
    System.out.println("file too big...");
    return null;
  }
  FileInputStream fi = new FileInputStream(file);
  byte[] buffer = new byte[(int) fileSize];
  int offset = 0;
  int numRead = 0;
  while (offset < buffer.length  && (numRead = fi.read(buffer, offset, buffer.length - offset)) >= 0) {
    offset += numRead;
  }
  // 确保所有数据均被读取
  if (offset != buffer.length) {
    throw new IOException("Could not completely read file " + file.getName());
  }
  fi.close();
  return buffer;
}
//拼接byte数据
public static byte[] byteMergerAll(byte[]... values){
   int length_byte=0;
   for(int i=0; i<values.length; i++){
    length_byte+=values[i].length;
   }
   byte[]all_byte = new byte[length_byte];
   int countLength = 0;
   for(int i=0; i<values.length; i++){
    System.arraycopy(values[i],0, all_byte, countLength, values[i].length);
    countLength += values[i].length;
   }
   return all_byte;
}
/**
* hex字符串转byte数组
* @param inHex 待转换的Hex字符串
* @return  转换后的byte数组结果
*/
public static byte[] hexToByteArray(String inHex){
  int hexlen = inHex.length();
  byte[] result;
  if (hexlen % 2 == 1){
    //奇数
    hexlen++;
    result = new byte[(hexlen/2)];
    inHex="0"+inHex;
  }else {
    //偶数
    result = new byte[(hexlen/2)];
  }
  
  int j=0;
  for (int i = 0; i < hexlen; i+=2){
    result[j]=hexToByte(inHex.substring(i,i+2));
    j++;
  }
  return result;
}

public static byte hexToByte(String inHex) {
    return (byte) Integer.parseInt(inHex, 16);
}

public class CRC16Standard {
    private static final int[] table = { 
    0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241, 0xC601, 0x06C0, 0x0780, 0xC741,
    0x0500, 0xC5C1, 0xC481, 0x0440, 0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40, 0x0A00, 0xCAC1, 0xCB81, 0x0B40,
    0xC901, 0x09C0, 0x0880, 0xC841, 0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40, 0x1E00, 0xDEC1, 0xDF81, 0x1F40,
    0xDD01, 0x1DC0, 0x1C80, 0xDC41, 0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641, 0xD201, 0x12C0, 0x1380, 0xD341,
    0x1100, 0xD1C1, 0xD081, 0x1040, 0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240, 0x3600, 0xF6C1, 0xF781, 0x3740,
    0xF501, 0x35C0, 0x3480, 0xF441, 0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41, 0xFA01, 0x3AC0, 0x3B80, 0xFB41,
    0x3900, 0xF9C1, 0xF881, 0x3840, 0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41, 0xEE01, 0x2EC0, 0x2F80, 0xEF41,
    0x2D00, 0xEDC1, 0xEC81, 0x2C40, 0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640, 0x2200, 0xE2C1, 0xE381, 0x2340,
    0xE101, 0x21C0, 0x2080, 0xE041, 0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240, 0x6600, 0xA6C1, 0xA781, 0x6740,
    0xA501, 0x65C0, 0x6480, 0xA441, 0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41, 0xAA01, 0x6AC0, 0x6B80, 0xAB41,
    0x6900, 0xA9C1, 0xA881, 0x6840, 0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41, 0xBE01, 0x7EC0, 0x7F80, 0xBF41,
    0x7D00, 0xBDC1, 0xBC81, 0x7C40, 0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640, 0x7200, 0xB2C1, 0xB381, 0x7340,
    0xB101, 0x71C0, 0x7080, 0xB041, 0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241, 0x9601, 0x56C0, 0x5780, 0x9741,
    0x5500, 0x95C1, 0x9481, 0x5440, 0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40, 0x5A00, 0x9AC1, 0x9B81, 0x5B40,
    0x9901, 0x59C0, 0x5880, 0x9841, 0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40, 0x4E00, 0x8EC1, 0x8F81, 0x4F40,
    0x8D01, 0x4DC0, 0x4C80, 0x8C41, 0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641, 0x8201, 0x42C0, 0x4380, 0x8341,
    0x4100, 0x81C1, 0x8081, 0x4040, 
    };

    public static byte[] getCRCBytes(byte[] data, int start, int len) {
    int crc = 0x0000;
    for (byte b : data) {
        crc = (crc >>> 8) ^ table[(crc ^ b) & 0xff];
    }
    return new byte[] { (byte) (0xff & crc), (byte) ((0xff00 & crc) >> 8) };
    }

    public static byte[] getCRCBytes(byte[] data) {
        return getCRCBytes(data, 0, data.length);
    }

  /**
  * 字节数组转16进制
  * @param bytes 需要转换的byte数组
  * @return  转换后的Hex字符串
  */
    public static String bytesToHex(byte[] bytes) {
    StringBuffer sb = new StringBuffer();
    for(int i = 0; i < bytes.length; i++) {
        String hex = Integer.toHexString(bytes[i] & 0xFF);
        if(hex.length() < 2){
            sb.append(0);
        }
        sb.append(hex);
    }
    return sb.toString();
    }

    // 测试
    public static void main(String[] args) {
        //byte[] data = new byte[]{0x53, 0x55, 0x46};
        byte[] data = new byte[] {(byte) 0xFF, (byte) 0xCA, 0x02, 0x00, 0x06, 0x01 };
        byte[] crc = CRC16Standard.getCRCBytes(data);
        System.out.println(bytesToHex(crc));
    }
}