smspducodec.java

Java写的通过手机收发短信息的程序。

//
// Copyright (c) 2001 Kvanttisofta oy.  All rights reserved.
//
//
// SMS PDU coder/encoder class.
// ([e-mail]).
//
// $Id: SmsPduCodec.java,v 1.1.1.1 2001/04/18 04:19:00 aspa Exp $.
//
// (based on info from: http://www.sics.se/~lpe/help/sms/)
//
// TODO:
// - more characters in GSM <==> ISO-8859-1 mapping.
// - GSM 7-bit alphabet extension table character support.
//
//

//
// NB1: with jikes you have to use the '-encoding 8859_1' option.
//

package fi.kvanttisofta.sms;

public class SmsPduCodec {
    private static final char EMPTYCHAR = 0x100;
    private static final char EXTTABLEESCAPE = 0x1B;
    private static char[] gsmToIsoMap; // GSM ==> ISO88591 
    private static char[] gsmToIsoExtMap;
    private static char[] isoToGsmMap; // ISO88591 ==> GSM
    private static char[] isoToGsmExtMap;

    private static char[] hexDigits = { '0', '1', '2', '3', '4', '5', '6', '7',
					'8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
    };

    // swaps characters of every two character substring of a string.
    public static String swapDigits(String str) {
	if( str == null )
	    return str;
	
	int strlen = str.length();
	StringBuffer sb = new StringBuffer(strlen);

	for(int i=0; (i+1) < strlen; i=i+2) {
	    sb.append(str.charAt(i+1));
	    sb.append(str.charAt(i));
	}
	return new String(sb);
    }

    // returns a hex string representation of a 8 bit integer.
    public static String toHexString(int b) {
	char[] digits = new char[2];
	b = b & 255;

	digits[0] = hexDigits[b / 0x10];
	digits[1] = hexDigits[b % 0x10];

	return new String(digits);
    }

    // returns an input string as a hex string. for debugging.
    public static String hexDump(String s) {
	StringBuffer dump = new StringBuffer();
	for(int i = 0; i<s.length(); i++)
	    dump.append(SmsPduCodec.toHexString(s.charAt(i)));
	return new String(dump);
    }

    // converts a string of 7 bit characters to a sequence of
    // of 8 bit bytes encoded as hex strings.
    public static String sevenBitEncode(String message) {
	if(message == null)
	    return message;
	StringBuffer msg = new StringBuffer(message);

	StringBuffer encmsg = new StringBuffer(2*160);
	int bb = 0, bblen = 0, i;
	char o=0, c=0, tc;

	for(i=0; i < msg.length() || bblen>=8; i++) {
	    if(i<msg.length()) {
		c = msg.charAt(i);
		tc = isoToGsmMap[c];
		/*
		  if(tc == EXTTABLEESCAPE) {
		  //msg.insert(i+1, isoToGsmExtMap[c]);
		  }
		*/
		c = tc;

		c &= ~(1 << 7); // clear (discard) eight bit.
		bb |= (c << bblen); // insert c to bb.
		bblen += 7;		
	    }

	    while(bblen >= 8) { // we have a full octet.
		o = (char) (bb & 255); // take 8 bits.
		encmsg.append(SmsPduCodec.toHexString(o));
		bb >>>= 8;
		bblen -= 8;
	    }

	} // end: for(i=0; i<msglen || bblen>=8; i++) {

	if( (bblen > 0) )
	    encmsg.append(SmsPduCodec.toHexString(bb));

	return encmsg.toString();
    }

    public static String sevenBitDecode(String encmsg) {
	return sevenBitDecode(encmsg, encmsg.length());
    }

    // converts a sequence of 8 bit bytes encoded as hex
    // strings to a string of 7 bit characters.
    public static String sevenBitDecode(String encmsg, int msglen)
	throws NumberFormatException {
	// encmsg: encoded string to decode.
	// msglen: the requested number of characters to decode.

	int i, o, r=0, rlen=0, olen=0, charcnt=0; // ints are 32 bit long.
	StringBuffer msg = new StringBuffer(160);
	int encmsglen = encmsg.length();
	String ostr;
	boolean exttableescape = false;
	char c;

	// assumes even number of chars in octet string.
	for(i=0; ((i+1)<encmsglen) && (charcnt<msglen); i=i+2) {
	    ostr = encmsg.substring(i, i+2);
	    o = Integer.parseInt(ostr, 16);
	    olen = 8;

	    if(rlen >= 7) { // take a full char off remainder.
		c = (char) (r & 127);
		r >>>= 7;
		rlen -= 7;
		msg.append(c);
		charcnt++;
	    }

	    o <<= rlen; // push remainding bits from r to o.
	    o |= r;
	    olen += rlen;

	    c = (char) (o & 127); // get first 7 bits from o.
	    o >>>= 7;
	    olen -= 7;

	    r = o; // put remainding bits from o to r.
	    rlen = olen;

	    // handle character conversion.
	    c = gsmToIsoMap[c];

	    if( c == EXTTABLEESCAPE ) { // ext table character handling.
		exttableescape = true;
		continue;
	    } else if( exttableescape == true) {
		exttableescape = false;
		c = gsmToIsoExtMap[c];
	    }

	    msg.append(c);
	    charcnt++;
	} // end: for(i=0; ((i+1)<encmsglen) && (charcnt<msglen); i=i+2) {

	if( (rlen>0) && (charcnt<msglen) )
	    msg.append((char)r);

	return msg.toString();
    }

    // class initialization.
    static {
	// construct GSM alphabet to/from ISO mappings.
	char[] gsmiso = { 0, '@', 1, '