https://download.csdn.net/download/chongchi_wxcc/86618299
Download YModem, you can directly use android studio to import it as a module, and you can directly call YModem.java when using it
send(File file) method
During development, if you encounter the need to use the YModem protocol for firmware upgrades in the APP, record it
1. First look at the transmission process of the YModem protocol
The picture above is the normal file transfer process of the YModem protocol
2. Packet format during transmission
(1) File information packet format
(2) File stream packet format
Send the file stream data packet, the serial number starts from 01, and superimposes 1 in turn, until the file is read and sent to the end
(3) All 0 packets
Note:
NAK (0x15) If NAK is received during data transmission, the data packet needs to be sent to the lower computer again
CAN (0x18) If CAN is received during data transmission, the transmission can be interrupted directly
3. Code
public boolean send(File file) {
try {
CRC crc = new CRC16();
//Send file information packet
String fileNameString = file.getName() + (char)0 + file.length();
byte[] fileNameBytes = Arrays.copyOf(fileNameString.getBytes(), 128);
modem.sendFileInfo(0, Arrays.copyOf(fileNameBytes, 128), 128, crc);
Thread.sleep(20);
//send file stream packet
byte[] block = new byte[1024];
DataInputStream dataStream = new DataInputStream(new FileInputStream(file));
modem.sendDataBlocks(dataStream, 1, crc, block);
Thread.sleep(20);
//send EOT
modem.sendEOT();
Thread.sleep(20);
//Send all 0 packets
modem.sendFileZero();
return true;
}catch (Exception e) {
e.printStackTrace();
}
return false;
}
public class CRC16 implements CRC {
private static int[] table = {
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,
};
@Override
public int getCRCLength() {
return 2;
}
@Override
public long calcCRC(byte[] block) {
int crc = 0x0000;
for (byte b : block) {
crc = ((crc << 8) ^ table[((crc >> 8) ^ (0xff & b))]) & 0xFFFF;
}
return crc;
}
}
class Modem {
/* Protocol characters used */
protected static final byte SOH = 0x01; /* Start Of Header */
protected static final byte STX = 0x02; /* Start Of Text (used like SOH but means 1024 block size) */
protected static final byte EOT = 0x04; /* End Of Transmission */
protected static final byte ACK = 0x06; /* ACKnowlege */
protected static final byte NAK = 0x15; /* Negative AcKnowlege */
protected static final byte CAN = 0x18; /* CANcel character */
protected static final byte CPMEOF = 0x1A;
protected static final byte ST_C = 'C';
protected static final int MAXERRORS = 10;
private InputStream inputStream;
private OutputStream outputStream;
private boolean isReading = true;
/**
* Constructor
*
* @param inputStream stream for reading received data from other side
* @param outputStream stream for writing data to other side
*/
protected Modem(InputStream inputStream, OutputStream outputStream) {
this.inputStream = inputStream;
this.outputStream = outputStream;
isReading = true;
}
protected void sendDataBlocks(DataInputStream dataStream, int blockNumber, CRC crc, byte[] block) throws IOException {
int dataLength;
while ((dataLength = dataStream.read(block)) != -1) {
sendBlock(blockNumber++, block, dataLength, crc);
}
}
public void sendFileZero() throws IOException {
int errorCount = 0;
int character;
while (errorCount < 6) {
byte seq = 0x00;
byte[] data = YModemUtils.getDataPackage(new byte[128], 128, seq, new CRC16());
outputStream.write(data);
outputStream.flush();
try {
character = readByte();
if (character == ACK) {
break;
} else if (character == CAN) {
throw new IOException("Transmission terminated");
}
} catch (Exception ignored) {
}
errorCount++;
}
}
protected void sendEOT() throws IOException {
int errorCount = 0;
int character;
while (errorCount < 10) {
sendByte(EOT);
try {
character = readByte();
if (character == ACK) {
return;
} else if (character == CAN) {
throw new IOException("Transmission terminated");
}
} catch (Exception ignored) {
}
errorCount++;
}
}
protected void sendFileInfo(int blockNumber, byte[] block, int dataLength, CRC crc) throws IOException {
int errorCount;
byte character;
if (dataLength < block.length) {
block[dataLength] = CPMEOF;
}
errorCount = 0;
while (errorCount < MAXERRORS)
{
byte head;
if (block.length == 1024) {
head = STX;
} else { //128
head = SOH;
}
byte[] headByte = YModemUtils.getDataHeader(ChatUtils.intToBytes(blockNumber)[0], head);
byte[] crcbyte = writeCRC(block, crc);
byte[] fileData = YModemUtils.concat(headByte, block, crcbyte);
outputStream.write(fileData);
outputStream.flush();
boolean receiveACK = false;
while (true) {
try {
character = readByte();
if (character == ACK) {
receiveACK = true;
} else if (character == NAK) {
errorCount++;
shortSleepTime(10);
break;
} else if (character == ST_C) {
if(receiveACK) {
shortSleepTime(10);
return;
} else {
errorCount++;
shortSleepTime(10);
break;
}
} else if (character == CAN) {
throw new IOException("Transmission terminated");
}else {
throw new IOException("Transmission terminated");
}
} catch (Exception e) {
errorCount++;
break;
}
}
}
throw new IOException("Too many errors caught, abandoning transfer");
}
protected void sendBlock(int blockNumber, byte[] block, int dataLength, CRC crc) throws IOException {
int errorCount;
byte character;
if (dataLength < block.length) {
block[dataLength] = CPMEOF;
}
errorCount = 0;
while (errorCount < MAXERRORS)
{
byte head;
if (block.length == 1024) {
head = STX;
} else { //128
head = SOH;
}
byte[] headByte = YModemUtils.getDataHeader(ChatUtils.intToBytes(blockNumber)[0], head);
byte[] crcbyte = writeCRC(block, crc);
byte[] fileData = YModemUtils.concat(headByte, block, crcbyte);
outputStream.write(fileData);
outputStream.flush();
while (true) {
try {
character = readByte();
if (character == ACK) {
shortSleepTime(10);
return;
} else if (character == NAK) {
errorCount++;
shortSleepTime(10);
break;
} else if (character == ST_C) {
errorCount++;
shortSleepTime(10);
break;
} else if (character == CAN) {
throw new IOException("Transmission terminated");
}else {
throw new IOException("Transmission terminated");
}
} catch (Exception e) {
errorCount++;
break;
}
}
}
throw new IOException("Too many errors caught, abandoning transfer");
}
protected void sendByte(byte b) throws IOException {
outputStream.write(b);
outputStream.flush();
}
private void shortSleep() {
try {
Thread.sleep(2);
} catch (InterruptedException e) {
try {
interruptTransmission();
} catch (IOException ignore) {
}
throw new RuntimeException("Transmission was interrupted", e);
}
}
private byte readByte() throws IOException {
while (isReading) {
if (inputStream != null && inputStream.available() > 0) {
int b = inputStream.read();
return (byte) b;
}
shortSleep();
}
throw new IOException("read end");
}
}