使用java实现Xmodem协议

public class Xmodem {

 // 开始
 private final byte SOH = 0x01;
 // 结束
 private final byte EOT = 0x04;
 // 应答
 private final byte ACK = 0x06;
 // 重传
 private final byte NAK = 0x15;
 // 无条件结束
 private final byte CAN = 0x18;

 // 以128字节块的形式传输数据
 private final int SECTOR_SIZE = 128;
 // 最大错误（无应答）包数
 private final int MAX_ERRORS = 10;

 // 输入流，用于读取串口数据
 private InputStream inputStream;
 // 输出流，用于发送串口数据
 private OutputStream outputStream;

 public Xmodem(InputStream inputStream, OutputStream outputStream) {
 this.inputStream = inputStream;
 this.outputStream = outputStream;
 }

 /**
 * 发送数据
 * 
 * @param filePath
 *  文件路径
 */
 public void send(final String filePath) {
 new Thread() {
  public void run() {
  try {
   // 错误包数
   int errorCount;
   // 包序号
   byte blockNumber = 0x01;
   // 校验和
   int checkSum;
   // 读取到缓冲区的字节数量
   int nbytes;
   // 初始化数据缓冲区
   byte[] sector = new byte[SECTOR_SIZE];
   // 读取文件初始化
   DataInputStream inputStream = new DataInputStream(
    new FileInputStream(filePath));

   while ((nbytes = inputStream.read(sector)) > 0) {
   // 如果最后一包数据小于128个字节，以0xff补齐
   if (nbytes < SECTOR_SIZE) {
    for (int i = nbytes; i < SECTOR_SIZE; i++) {
    sector[i] = (byte) 0xff;
    }
   }

   // 同一包数据最多发送10次
   errorCount = 0;
   while (errorCount < MAX_ERRORS) {
    // 组包
    // 控制字符 + 包序号 + 包序号的反码 + 数据 + 校验和
    putData(SOH);
    putData(blockNumber);
    putData(~blockNumber);
    checkSum = CRC16.calc(sector) & 0x00ffff;
    putChar(sector, (short) checkSum);
    outputStream.flush();

    // 获取应答数据
    byte data = getData();
    // 如果收到应答数据则跳出循环，发送下一包数据
    // 未收到应答，错误包数+1，继续重发
    if (data == ACK) {
    break;
    } else {
    ++errorCount;
    }
   }
   // 包序号自增
   blockNumber = (byte) ((++blockNumber) % 256);
   }

   // 所有数据发送完成后，发送结束标识
   boolean isAck = false;
   while (!isAck) {
   putData(EOT);
   isAck = getData() == ACK;
   }
  } catch (Exception e) {
   e.printStackTrace();
  }
  };
 }.start();
 }

 /**
 * 接收数据
 * 
 * @param filePath
 *  文件路径
 * @return 是否接收完成
 * @throws IOException
 *  异常
 */
 public boolean receive(String filePath) throws Exception {
 // 错误包数
 int errorCount = 0;
 // 包序号
 byte blocknumber = 0x01;
 // 数据
 byte data;
 // 校验和
 int checkSum;
 // 初始化数据缓冲区
 byte[] sector = new byte[SECTOR_SIZE];
 // 写入文件初始化
 DataOutputStream outputStream = new DataOutputStream(
  new FileOutputStream(filePath));

 // 发送字符C，CRC方式校验
 putData((byte) 0x43);

 while (true) {
  if (errorCount > MAX_ERRORS) {
  outputStream.close();
  return false;
  }

  // 获取应答数据
  data = getData();
  if (data != EOT) {
  try {
   // 判断接收到的是否是开始标识
   if (data != SOH) {
   errorCount++;
   continue;
   }

   // 获取包序号
   data = getData();
   // 判断包序号是否正确
   if (data != blocknumber) {
   errorCount++;
   continue;
   }

   // 获取包序号的反码
   byte _blocknumber = (byte) ~getData();
   // 判断包序号的反码是否正确
   if (data != _blocknumber) {
   errorCount++;
   continue;
   }

   // 获取数据
   for (int i = 0; i < SECTOR_SIZE; i++) {
   sector[i] = getData();
   }

   // 获取校验和
   checkSum = (getData() & 0xff) << 8;
   checkSum |= (getData() & 0xff);
   // 判断校验和是否正确
   int crc = CRC16.calc(sector);
   if (crc != checkSum) {
   errorCount++;
   continue;
   }

   // 发送应答
   putData(ACK);
   // 包序号自增
   blocknumber++;
   // 将数据写入本地
   outputStream.write(sector);
   // 错误包数归零
   errorCount = 0;

  } catch (Exception e) {
   e.printStackTrace();

  } finally {
   // 如果出错发送重传标识
   if (errorCount != 0) {
   putData(NAK);
   }
  }
  } else {
  break;
  }
 }

 // 关闭输出流
 outputStream.close();
 // 发送应答
 putData(ACK);

 return true;
 }

 /**
 * 获取数据
 * 
 * @return 数据
 * @throws IOException
 *  异常
 */
 private byte getData() throws IOException {
 return (byte) inputStream.read();
 }

 /**
 * 发送数据
 * 
 * @param data
 *  数据
 * @throws IOException
 *  异常
 */
 private void putData(int data) throws IOException {
 outputStream.write((byte) data);
 }

 /**
 * 发送数据
 * 
 * @param data
 *  数据
 * @param checkSum
 *  校验和
 * @throws IOException
 *  异常
 */
 private void putChar(byte[] data, short checkSum) throws IOException {
 ByteBuffer bb = ByteBuffer.allocate(data.length + 2).order(
  ByteOrder.BIG_ENDIAN);
 bb.put(data);
 bb.putShort(checkSum);
 outputStream.write(bb.array());
 }
}

public class CRC16 {

 private static final char crctable[] = { 0x0000, 0x1021, 0x2042, 0x3063,
  0x4084, 0x50a5, 0x60c6, 0x70e7, 0x8108, 0x9129, 0xa14a, 0xb16b,
  0xc18c, 0xd1ad, 0xe1ce, 0xf1ef, 0x1231, 0x0210, 0x3273, 0x2252,
  0x52b5, 0x4294, 0x72f7, 0x62d6, 0x9339, 0x8318, 0xb37b, 0xa35a,
  0xd3bd, 0xc39c, 0xf3ff, 0xe3de, 0x2462, 0x3443, 0x0420, 0x1401,
  0x64e6, 0x74c7, 0x44a4, 0x5485, 0xa56a, 0xb54b, 0x8528, 0x9509,
  0xe5ee, 0xf5cf, 0xc5ac, 0xd58d, 0x3653, 0x2672, 0x1611, 0x0630,
  0x76d7, 0x66f6, 0x5695, 0x46b4, 0xb75b, 0xa77a, 0x9719, 0x8738,
  0xf7df, 0xe7fe, 0xd79d, 0xc7bc, 0x48c4, 0x58e5, 0x6886, 0x78a7,
  0x0840, 0x1861, 0x2802, 0x3823, 0xc9cc, 0xd9ed, 0xe98e, 0xf9af,
  0x8948, 0x9969, 0xa90a, 0xb92b, 0x5af5, 0x4ad4, 0x7ab7, 0x6a96,
  0x1a71, 0x0a50, 0x3a33, 0x2a12, 0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e,
  0x9b79, 0x8b58, 0xbb3b, 0xab1a, 0x6ca6, 0x7c87, 0x4ce4, 0x5cc5,
  0x2c22, 0x3c03, 0x0c60, 0x1c41, 0xedae, 0xfd8f, 0xcdec, 0xddcd,
  0xad2a, 0xbd0b, 0x8d68, 0x9d49, 0x7e97, 0x6eb6, 0x5ed5, 0x4ef4,
  0x3e13, 0x2e32, 0x1e51, 0x0e70, 0xff9f, 0xefbe, 0xdfdd, 0xcffc,
  0xbf1b, 0xaf3a, 0x9f59, 0x8f78, 0x9188, 0x81a9, 0xb1ca, 0xa1eb,
  0xd10c, 0xc12d, 0xf14e, 0xe16f, 0x1080, 0x00a1, 0x30c2, 0x20e3,
  0x5004, 0x4025, 0x7046, 0x6067, 0x83b9, 0x9398, 0xa3fb, 0xb3da,
  0xc33d, 0xd31c, 0xe37f, 0xf35e, 0x02b1, 0x1290, 0x22f3, 0x32d2,
  0x4235, 0x5214, 0x6277, 0x7256, 0xb5ea, 0xa5cb, 0x95a8, 0x8589,
  0xf56e, 0xe54f, 0xd52c, 0xc50d, 0x34e2, 0x24c3, 0x14a0, 0x0481,
  0x7466, 0x6447, 0x5424, 0x4405, 0xa7db, 0xb7fa, 0x8799, 0x97b8,
  0xe75f, 0xf77e, 0xc71d, 0xd73c, 0x26d3, 0x36f2, 0x0691, 0x16b0,
  0x6657, 0x7676, 0x4615, 0x5634, 0xd94c, 0xc96d, 0xf90e, 0xe92f,
  0x99c8, 0x89e9, 0xb98a, 0xa9ab, 0x5844, 0x4865, 0x7806, 0x6827,
  0x18c0, 0x08e1, 0x3882, 0x28a3, 0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e,
  0x8bf9, 0x9bd8, 0xabbb, 0xbb9a, 0x4a75, 0x5a54, 0x6a37, 0x7a16,
  0x0af1, 0x1ad0, 0x2ab3, 0x3a92, 0xfd2e, 0xed0f, 0xdd6c, 0xcd4d,
  0xbdaa, 0xad8b, 0x9de8, 0x8dc9, 0x7c26, 0x6c07, 0x5c64, 0x4c45,
  0x3ca2, 0x2c83, 0x1ce0, 0x0cc1, 0xef1f, 0xff3e, 0xcf5d, 0xdf7c,
  0xaf9b, 0xbfba, 0x8fd9, 0x9ff8, 0x6e17, 0x7e36, 0x4e55, 0x5e74,
  0x2e93, 0x3eb2, 0x0ed1, 0x1ef0 };

 public static char calc(byte[] bytes) {
 char crc = 0x0000;
 for (byte b : bytes) {
  crc = (char) ((crc << 8) ^ crctable[((crc >> 8) ^ b) & 0x00ff]);
 }
 return (char) (crc);
 }
}

// serialPort为串口对象
Xmodem xmodem = new Xmodem(serialPort.getInputStream(),serialPort.getOutputStream());
// filePath为文件路径
// ./bin/xxx.bin
xmodem.send(filePath);