在Java中实现X-modem协议
我想从串口接收文件，我必须使用X-modem协议设计用于通过Java中的串行端口接收文件。 所以，如果有人能够了解那么请帮助我。 我很麻烦.plz
这里是。
我在JModem源代码中找到了这个。 如果你看看它写出数据的位置，你可以看到它做了SOH，blocknum，~blocknum，数据和校验和。 它使用128的扇区大小。这些组成了标准的XModem协议 。 它也很简单，可以从这里做XModem1K，YModem和ZModem。
/** * a tiny version of Ward Christensen's MODEM program for UNIX. * Written ~ 1980 by Andrew Scott Beals. Last revised 1982. * AD 2000 - dragged from the archives for use in Java Cookbook. * * @author C version by Andrew Scott Beals, sjobrg.andy%mit-oz@mit-mc.arpa. * @author Java version by Ian F. Darwin, ian@darwinsys.com * $Id: TModem.java,v 1.8 2000/03/02 03:40:50 ian Exp $ */ class TModem { protected final byte CPMEOF = 26; /* control/z */ protected final int MAXERRORS = 10; /* max times to retry one block */ protected final int SECSIZE = 128; /* cpm sector, transmission block */ protected final int SENTIMOUT = 30; /* timeout time in send */ protected final int SLEEP = 30; /* timeout time in recv */ /* Protocol characters used */ protected final byte SOH = 1; /* Start Of Header */ protected final byte EOT = 4; /* End Of Transmission */ protected final byte ACK = 6; /* ACKnowlege */ protected final byte NAK = 0x15; /* Negative AcKnowlege */ protected InputStream inStream; protected OutputStream outStream; protected PrintWriter errStream; /** Construct a TModem */ public TModem(InputStream is, OutputStream os, PrintWriter errs) { inStream = is; outStream = os; errStream = errs; } /** Construct a TModem with default files (stdin and stdout). */ public TModem() { inStream = System.in; outStream = System.out; errStream = new PrintWriter(System.err); } /** A main program, for direct invocation. */ public static void main(String[] argv) throws IOException, InterruptedException { /* argc must == 2, ie, `java TModem -s filename' */ if (argv.length != 2) usage(); if (argv[0].charAt(0) != '-') usage(); TModem tm = new TModem(); tm.setStandalone(true); boolean OK = false; switch (argv[0].charAt(1)){ case 'r': OK = tm.receive(argv[1]); break; case 's': OK = tm.send(argv[1]); break; default: usage(); } System.out.print(OK?"Done OK":"Failed"); System.exit(0); } /* give user minimal usage message */ protected static void usage() { System.err.println("usage: TModem -r/-s file"); // not errStream, not die(), since this is static. System.exit(1); } /** If we're in a standalone app it is OK to System.exit() */ protected boolean standalone = false; public void setStandalone(boolean is) { standalone = is; } public boolean isStandalone() { return standalone; } /** A flag used to communicate with inner class IOTimer */ protected boolean gotChar; /** An inner class to provide a read timeout for alarms. */ class IOTimer extends Thread { String message; long milliseconds; /** Construct an IO Timer */ IOTimer(long sec, String mesg) { milliseconds = 1000 * sec; message = mesg; } public void run() { try { Thread.sleep(milliseconds); } catch (InterruptedException e) { // can't happen } /** Implement the timer */ if (!gotChar) errStream.println("Timed out waiting for " + message); die(1); } } /* * send a file to the remote */ public boolean send(String tfile) throws IOException, InterruptedException { char checksum, index, blocknumber, errorcount; byte character; byte[] sector = new byte[SECSIZE]; int nbytes; DataInputStream foo; foo = new DataInputStream(new FileInputStream(tfile)); errStream.println( "file open, ready to send"); errorcount = 0; blocknumber = 1; // The C version uses "alarm()", a UNIX-only system call, // to detect if the read times out. Here we do detect it // by using a Thread, the IOTimer class defined above. gotChar = false; new IOTimer(SENTIMOUT, "NAK to start send").start(); do { character = getchar(); gotChar = true; if (character != NAK && errorcount < MAXERRORS) ++errorcount; } while (character != NAK && errorcount < MAXERRORS); errStream.println( "transmission beginning"); if (errorcount == MAXERRORS) { xerror(); } while ((nbytes=inStream.read(sector))!=0) { if (nbytes SerialIO有商业实现。
嗯…只需阅读规范 ，并实施它。 它看起来并不太难，虽然一般来说在Java中的字节级别上徘徊是很尴尬的。
我没有大量搜索现有的实现，我敢肯定，除了kgiannakakis建议的商业用途之外，通常都有。 :)否则可能退一步，并获得一些C源来查看并重新实现Java（当然是许可证）。
这个程序真的有效吗？ 我正在尝试使用它，但我一直都有例外。 在发送部分，代码根本不使用文件名…
如果您使用JModem，当您使用传输按钮时，另一端会收到字符串“tmodem -r at.ht”或-s（如果您正在接收）。 但是我没有看到这一端用字符串做任何事……它只显示在文本区域……