ie.omk.smpp.util.DefaultAlphabetEncoding Maven / Gradle / Ivy
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package ie.omk.smpp.util;
import java.io.ByteArrayOutputStream;
/**
* This class encodes and decodes Java Strings to and from the SMS default
* alphabet. It also supports the default extension table. The default alphabet
* and it's extension table is defined in GSM 03.38.
*/
public class DefaultAlphabetEncoding extends ie.omk.smpp.util.AlphabetEncoding {
private static final int DCS = 0;
public static final int EXTENDED_ESCAPE = 0x1b;
/** Page break (extended table). */
public static final int PAGE_BREAK = 0x0a;
private static final char[] CHAR_TABLE = {
'@', '\u00a3', '$', '\u00a5', '\u00e8', '\u00e9', '\u00f9', '\u00ec',
'\u00f2', '\u00c7', '\n', '\u00d8', '\u00f8', '\r', '\u00c5', '\u00e5',
'\u0394', '_', '\u03a6', '\u0393', '\u039b', '\u03a9', '\u03a0', '\u03a8',
'\u03a3', '\u0398', '\u039e', ' ', '\u00c6', '\u00e6', '\u00df', '\u00c9',
' ', '!', '"', '#', '\u00a4', '%', '&', '\'',
'(', ')', '*', '+', ',', '-', '.', '/',
'0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', ':', ';', '<', '=', '>', '?',
'\u00a1', 'A', 'B', 'C', 'D', 'E', 'F', 'G',
'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
'X', 'Y', 'Z', '\u00c4', '\u00d6', '\u00d1', '\u00dc', '\u00a7',
'\u00bf', 'a', 'b', 'c', 'd', 'e', 'f', 'g',
'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
'p', 'q', 'r', 's', 't', 'u', 'v', 'w',
'x', 'y', 'z', '\u00e4', '\u00f6', '\u00f1', '\u00fc', '\u00e0',
};
/**
* Extended character table. Characters in this table are accessed by the
* 'escape' character in the base table. It is important that none of the
* 'inactive' characters ever be matchable with a valid base-table
* character as this breaks the encoding loop.
*
* @see #EXTENDED_ESCAPE
*/
private static final char[] EXT_CHAR_TABLE = {
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, '^', 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
'{', '}', 0, 0, 0, 0, 0, '\\',
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, '[', '~', ']', 0,
'|', 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, '\u20ac', 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
};
private static final DefaultAlphabetEncoding INSTANCE = new DefaultAlphabetEncoding();
public DefaultAlphabetEncoding() {
super(DCS);
}
/**
* Get the singleton instance of DefaultAlphabetEncoding.
* @deprecated
*/
public static DefaultAlphabetEncoding getInstance() {
return INSTANCE;
}
/**
* Decode an SMS default alphabet-encoded octet string into a Java String.
*/
public String decodeString(byte[] b) {
if (b == null) {
return "";
}
char[] table = CHAR_TABLE;
StringBuffer buf = new StringBuffer();
for (int i = 0; i < b.length; i++) {
int code = (int) b[i] & 0x000000ff;
if (code == EXTENDED_ESCAPE) {
// take next char from extension table
table = EXT_CHAR_TABLE;
} else {
buf.append((code >= table.length) ? '?' : table[code]);
// Go back to the default table.
table = CHAR_TABLE;
}
}
return buf.toString();
}
/**
* Encode a Java String into a byte array using the SMS Default alphabet.
*/
public byte[] encodeString(String s) {
if (s == null) {
return new byte[0];
}
char[] c = s.toCharArray();
ByteArrayOutputStream enc = new ByteArrayOutputStream(256);
for (int loop = 0; loop < c.length; loop++) {
int search = 0;
for (; search < CHAR_TABLE.length; search++) {
if (search == EXTENDED_ESCAPE) {
continue;
}
if (c[loop] == CHAR_TABLE[search]) {
enc.write((byte) search);
break;
}
if (c[loop] == EXT_CHAR_TABLE[search]) {
enc.write((byte) EXTENDED_ESCAPE);
enc.write((byte) search);
break;
}
}
if (search == CHAR_TABLE.length) {
// A '?' character.
enc.write(0x3f);
}
}
return enc.toByteArray();
}
public int getEncodingLength() {
return 7;
}
/**
* Pack a byte array according to the GSM bit-packing algorithm.
* The GSM specification defines a simple compression mechanism for its
* default alphabet to pack more message characters into a smaller space.
* Since the alphabet only contains 128 symbols, each one can be represented
* in 7 bits. The packing algorithm squeezes the bits for each symbol
* "down" into the preceeding byte (so bit 7 of the first byte actually
* contains bit 0 of the second symbol in a default alphabet string, bits
* 6 and 7 in the second byte contain bits 0 and 1 of the third symbol etc.)
* Since the maximum short message length is 140 bytes, you save
* one bit per byte using the default alphabet giving you a total of
* 140 + (140 / 8) = 160 characters to use. This is where the 160 character
* limit comes from in SMPP packets.
*
* Having said all that, most SMSCs do NOT use the packing
* algorithm when communicating over TCP/IP. They either use a full
* 8-bit alphabet such as ASCII or Latin-1, or they accept the default
* alphabet in its unpacked form. As such, you will be unlikely to
* need this method.
*
* @param unpacked The unpacked byte array.
* @return A new byte array containing the bytes in their packed form.
*/
public byte[] pack(byte[] unpacked) {
int packedLen = unpacked.length - (unpacked.length / 8);
byte[] packed = new byte[packedLen];
int pos = 0;
int i = 0;
while (i < unpacked.length) {
int jmax = (i + 7) > unpacked.length ? unpacked.length - i : 7;
int mask = 0x1;
for (int j = 0; j < jmax; j++) {
int b1 = (int) unpacked[i + j] & 0xff;
int b2 = 0x0;
try {
b2 = (int) unpacked[i + j + 1] & mask;
} catch (ArrayIndexOutOfBoundsException x) {
}
packed[pos++] = (byte) ((b1 >>> j) | (b2 << (8 - (j + 1))));
mask = (mask << 1) | 1;
}
i += 8;
}
return packed;
}
/**
* Unpack a byte array according to the GSM bit-packing algorithm.
* Read the full description in the documentation of the
* pack method.
* @see #pack(byte[])
* @param packed The packed byte array.
* @return A new byte array containing the unpacked bytes.
*/
public byte[] unpack(byte[] packed) {
int unpackedLen = (packed.length * 8) / 7;
byte[] unpacked = new byte[unpackedLen];
int pos = 0;
int i = 0;
while (i < packed.length) {
int mask = 0x7f;
int jmax = (i + 8) > packed.length ? (packed.length - i) : 8;
for (int j = 0; j < jmax; j++) {
int b1 = (int) packed[i + j] & mask;
int b2 = 0x0;
try {
b2 = (int) packed[(i + j) - 1] & 0x00ff;
} catch (ArrayIndexOutOfBoundsException x) {
}
unpacked[pos++] = (byte) ((b1 << j) | (b2 >>> (8 - j)));
mask >>= 1;
}
i += 7;
}
return unpacked;
}
public String toString() {
final String fmt = "{0,number,000}: {1} ";
final Object[] args = new Object[2];
StringBuffer b = new StringBuffer(256);
b.append("Table size: ").append(CHAR_TABLE.length).append('\n');
for (int i = 0; i < 16; i++) {
for (int j = 0; j < 8; j++) {
int pos = i + (16 * j);
args[0] = new Integer(pos);
if (CHAR_TABLE[pos] == '\r') {
args[1] = "CR";
} else if (CHAR_TABLE[pos] == '\n') {
args[1] = "LF";
} else if (CHAR_TABLE[pos] == ' ') {
args[1] = "SP";
} else {
args[1] = " " + CHAR_TABLE[pos];
}
b.append(java.text.MessageFormat.format(fmt, args));
}
b.append('\n');
}
return b.toString();
}
}