public class Xmodem { // 開始 private final byte SOH = 0x01; // 結(jié)束 private final byte EOT = 0x04; // 應(yīng)答 private final byte ACK = 0x06; // 重傳 private final byte NAK = 0x15; // 無條件結(jié)束 private final byte CAN = 0x18; // 以128字節(jié)塊的形式傳輸數(shù)據(jù) private final int SECTOR_SIZE = 128; // 最大錯(cuò)誤（無應(yīng)答）包數(shù) private final int MAX_ERRORS = 10; // 輸入流，用于讀取串口數(shù)據(jù) private InputStream inputStream; // 輸出流，用于發(fā)送串口數(shù)據(jù) private OutputStream outputStream; public Xmodem(InputStream inputStream, OutputStream outputStream) { this.inputStream = inputStream; this.outputStream = outputStream; } /** * 發(fā)送數(shù)據(jù) *  * @param filePath *  文件路徑 */ public void send(final String filePath) { new Thread() {  public void run() {  try {   // 錯(cuò)誤包數(shù)   int errorCount;   // 包序號(hào)   byte blockNumber = 0x01;   // 校驗(yàn)和   int checkSum;   // 讀取到緩沖區(qū)的字節(jié)數(shù)量   int nbytes;   // 初始化數(shù)據(jù)緩沖區(qū)   byte[] sector = new byte[SECTOR_SIZE];   // 讀取文件初始化   DataInputStream inputStream = new DataInputStream(    new FileInputStream(filePath));   while ((nbytes = inputStream.read(sector)) > 0) {   // 如果最后一包數(shù)據(jù)小于128個(gè)字節(jié)，以0xff補(bǔ)齊   if (nbytes < SECTOR_SIZE) {    for (int i = nbytes; i < SECTOR_SIZE; i++) {    sector[i] = (byte) 0xff;    }   }   // 同一包數(shù)據(jù)最多發(fā)送10次   errorCount = 0;   while (errorCount < MAX_ERRORS) {    // 組包    // 控制字符 + 包序號(hào) + 包序號(hào)的反碼 + 數(shù)據(jù) + 校驗(yàn)和    putData(SOH);    putData(blockNumber);    putData(~blockNumber);    checkSum = CRC16.calc(sector) & 0x00ffff;    putChar(sector, (short) checkSum);    outputStream.flush();    // 獲取應(yīng)答數(shù)據(jù)    byte data = getData();    // 如果收到應(yīng)答數(shù)據(jù)則跳出循環(huán)，發(fā)送下一包數(shù)據(jù)    // 未收到應(yīng)答，錯(cuò)誤包數(shù)+1，繼續(xù)重發(fā)    if (data == ACK) {    break;    } else {    ++errorCount;    }   }   // 包序號(hào)自增   blockNumber = (byte) ((++blockNumber) % 256);   }   // 所有數(shù)據(jù)發(fā)送完成后，發(fā)送結(jié)束標(biāo)識(shí)   boolean isAck = false;   while (!isAck) {   putData(EOT);   isAck = getData() == ACK;   }  } catch (Exception e) {   e.printStackTrace();  }  }; }.start(); } /** * 接收數(shù)據(jù) *  * @param filePath *  文件路徑 * @return 是否接收完成 * @throws IOException *  異常 */ public boolean receive(String filePath) throws Exception { // 錯(cuò)誤包數(shù) int errorCount = 0; // 包序號(hào) byte blocknumber = 0x01; // 數(shù)據(jù) byte data; // 校驗(yàn)和 int checkSum; // 初始化數(shù)據(jù)緩沖區(qū) byte[] sector = new byte[SECTOR_SIZE]; // 寫入文件初始化 DataOutputStream outputStream = new DataOutputStream(  new FileOutputStream(filePath)); // 發(fā)送字符C，CRC方式校驗(yàn) putData((byte) 0x43); while (true) {  if (errorCount > MAX_ERRORS) {  outputStream.close();  return false;  }  // 獲取應(yīng)答數(shù)據(jù)  data = getData();  if (data != EOT) {  try {   // 判斷接收到的是否是開始標(biāo)識(shí)   if (data != SOH) {   errorCount++;   continue;   }   // 獲取包序號(hào)   data = getData();   // 判斷包序號(hào)是否正確   if (data != blocknumber) {   errorCount++;   continue;   }   // 獲取包序號(hào)的反碼   byte _blocknumber = (byte) ~getData();   // 判斷包序號(hào)的反碼是否正確   if (data != _blocknumber) {   errorCount++;   continue;   }   // 獲取數(shù)據(jù)   for (int i = 0; i < SECTOR_SIZE; i++) {   sector[i] = getData();   }   // 獲取校驗(yàn)和   checkSum = (getData() & 0xff) << 8;   checkSum |= (getData() & 0xff);   // 判斷校驗(yàn)和是否正確   int crc = CRC16.calc(sector);   if (crc != checkSum) {   errorCount++;   continue;   }   // 發(fā)送應(yīng)答   putData(ACK);   // 包序號(hào)自增   blocknumber++;   // 將數(shù)據(jù)寫入本地   outputStream.write(sector);   // 錯(cuò)誤包數(shù)歸零   errorCount = 0;  } catch (Exception e) {   e.printStackTrace();  } finally {   // 如果出錯(cuò)發(fā)送重傳標(biāo)識(shí)   if (errorCount != 0) {   putData(NAK);   }  }  } else {  break;  } } // 關(guān)閉輸出流 outputStream.close(); // 發(fā)送應(yīng)答 putData(ACK); return true; } /** * 獲取數(shù)據(jù) *  * @return 數(shù)據(jù) * @throws IOException *  異常 */ private byte getData() throws IOException { return (byte) inputStream.read(); } /** * 發(fā)送數(shù)據(jù) *  * @param data *  數(shù)據(jù) * @throws IOException *  異常 */ private void putData(int data) throws IOException { outputStream.write((byte) data); } /** * 發(fā)送數(shù)據(jù) *  * @param data *  數(shù)據(jù) * @param checkSum *  校驗(yàn)和 * @throws IOException *  異常 */ 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為串口對(duì)象Xmodem xmodem = new Xmodem(serialPort.getInputStream(),serialPort.getOutputStream());// filePath為文件路徑// ./bin/xxx.binxmodem.send(filePath);