Java example source code file (CodeSetConversion.java)
The CodeSetConversion.java Java example source code/*
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package com.sun.corba.se.impl.encoding;
import java.util.Map;
import java.util.HashMap;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.IllegalCharsetNameException;
import java.nio.charset.MalformedInputException;
import java.nio.charset.UnsupportedCharsetException;
import java.nio.charset.UnmappableCharacterException;
import com.sun.corba.se.impl.logging.ORBUtilSystemException;
import com.sun.corba.se.impl.logging.OMGSystemException;
import com.sun.corba.se.spi.logging.CORBALogDomains;
/**
* Collection of classes, interfaces, and factory methods for
* CORBA code set conversion.
*
* This is mainly used to shield other code from the sun.io
* converters which might change, as well as provide some basic
* translation from conversion to CORBA error exceptions. Some
* extra work is required here to facilitate the way CORBA
* says it uses UTF-16 as of the 00-11-03 spec.
*
* REVISIT - Since the nio.Charset and nio.Charset.Encoder/Decoder
* use NIO ByteBuffer and NIO CharBuffer, the interaction
* and interface between this class and the CDR streams
* should be looked at more closely for optimizations to
* avoid unnecessary copying of data between char[] &
* CharBuffer and byte[] & ByteBuffer, especially
* DirectByteBuffers.
*
*/
public class CodeSetConversion
{
/**
* Abstraction for char to byte conversion.
*
* Must be used in the proper sequence:
*
* 1) convert
* 2) Optional getNumBytes and/or getAlignment (if necessary)
* 3) getBytes (see warning)
*/
public abstract static class CTBConverter
{
// Perform the conversion of the provided char or String,
// allowing the caller to query for more information
// before writing.
public abstract void convert(char chToConvert);
public abstract void convert(String strToConvert);
// How many bytes resulted from the conversion?
public abstract int getNumBytes();
// What's the maximum number of bytes per character?
public abstract float getMaxBytesPerChar();
public abstract boolean isFixedWidthEncoding();
// What byte boundary should the stream align to before
// calling writeBytes? For instance, a fixed width
// encoding with 2 bytes per char in a stream which
// doesn't encapsulate the char's bytes should align
// on a 2 byte boundary. (Ex: UTF16 in GIOP1.1)
//
// Note: This has no effect on the converted bytes. It
// is just information available to the caller.
public abstract int getAlignment();
// Get the resulting bytes. Warning: You must use getNumBytes()
// to determine the end of the data in the byte array instead
// of array.length! The array may be used internally, so don't
// save references.
public abstract byte[] getBytes();
}
/**
* Abstraction for byte to char conversion.
*/
public abstract static class BTCConverter
{
// In GIOP 1.1, interoperability can only be achieved with
// fixed width encodings like UTF-16. This is because wstrings
// specified how many code points follow rather than specifying
// the length in octets.
public abstract boolean isFixedWidthEncoding();
public abstract int getFixedCharWidth();
// Called after getChars to determine the true size of the
// converted array.
public abstract int getNumChars();
// Perform the conversion using length bytes from the given
// input stream. Warning: You must use getNumChars() to
// determine the correct length of the resulting array.
// The same array may be used internally over multiple
// calls.
public abstract char[] getChars(byte[] bytes, int offset, int length);
}
/**
* Implementation of CTBConverter which uses a nio.Charset.CharsetEncoder
* to do the real work. Handles translation of exceptions to the
* appropriate CORBA versions.
*/
private class JavaCTBConverter extends CTBConverter
{
private ORBUtilSystemException wrapper = ORBUtilSystemException.get(
CORBALogDomains.RPC_ENCODING ) ;
private OMGSystemException omgWrapper = OMGSystemException.get(
CORBALogDomains.RPC_ENCODING ) ;
// nio.Charset.CharsetEncoder actually does the work here
// have to use it directly rather than through String's interface
// because we want to know when errors occur during the conversion.
private CharsetEncoder ctb;
// Proper alignment for this type of converter. For instance,
// ASCII has alignment of 1 (1 byte per char) but UTF16 has
// alignment of 2 (2 bytes per char)
private int alignment;
// Char buffer to hold the input.
private char[] chars = null;
// How many bytes are generated from the conversion?
private int numBytes = 0;
// How many characters were converted (temporary variable
// for cross method communication)
private int numChars = 0;
// ByteBuffer holding the converted input. This is necessary
// since we have to do calculations that require the conversion
// before writing the array to the stream.
private ByteBuffer buffer;
// What code set are we using?
private OSFCodeSetRegistry.Entry codeset;
public JavaCTBConverter(OSFCodeSetRegistry.Entry codeset,
int alignmentForEncoding) {
try {
ctb = cache.getCharToByteConverter(codeset.getName());
if (ctb == null) {
Charset tmpCharset = Charset.forName(codeset.getName());
ctb = tmpCharset.newEncoder();
cache.setConverter(codeset.getName(), ctb);
}
} catch(IllegalCharsetNameException icne) {
// This can only happen if one of our Entries has
// an invalid name.
throw wrapper.invalidCtbConverterName(icne,codeset.getName());
} catch(UnsupportedCharsetException ucne) {
// This can only happen if one of our Entries has
// an unsupported name.
throw wrapper.invalidCtbConverterName(ucne,codeset.getName());
}
this.codeset = codeset;
alignment = alignmentForEncoding;
}
public final float getMaxBytesPerChar() {
return ctb.maxBytesPerChar();
}
public void convert(char chToConvert) {
if (chars == null)
chars = new char[1];
// The CharToByteConverter only takes a char[]
chars[0] = chToConvert;
numChars = 1;
convertCharArray();
}
public void convert(String strToConvert) {
// Try to save a memory allocation if possible. Usual
// space/time trade off. If we could get the char[] out of
// the String without copying, that would be great, but
// it's forbidden since String is immutable.
if (chars == null || chars.length < strToConvert.length())
chars = new char[strToConvert.length()];
numChars = strToConvert.length();
strToConvert.getChars(0, numChars, chars, 0);
convertCharArray();
}
public final int getNumBytes() {
return numBytes;
}
public final int getAlignment() {
return alignment;
}
public final boolean isFixedWidthEncoding() {
return codeset.isFixedWidth();
}
public byte[] getBytes() {
// Note that you can't use buffer.length since the buffer might
// be larger than the actual number of converted bytes depending
// on the encoding.
return buffer.array();
}
private void convertCharArray() {
try {
// Possible optimization of directly converting into the CDR buffer.
// However, that means the CDR code would have to reserve
// a 4 byte string length ahead of time, and we'd need a
// confusing partial conversion scheme for when we couldn't
// fit everything in the buffer but needed to know the
// converted length before proceeding due to fragmentation.
// Then there's the issue of the chunking code.
//
// For right now, this is less messy and basic tests don't
// show more than a 1 ms penalty worst case. Less than a
// factor of 2 increase.
// Convert the characters
buffer = ctb.encode(CharBuffer.wrap(chars,0,numChars));
// ByteBuffer returned by the encoder will set its limit
// to byte immediately after the last written byte.
numBytes = buffer.limit();
} catch (IllegalStateException ise) {
// an encoding operation is already in progress
throw wrapper.ctbConverterFailure( ise ) ;
} catch (MalformedInputException mie) {
// There were illegal Unicode char pairs
throw wrapper.badUnicodePair( mie ) ;
} catch (UnmappableCharacterException uce) {
// A character doesn't map to the desired code set
// CORBA formal 00-11-03.
throw omgWrapper.charNotInCodeset( uce ) ;
} catch (CharacterCodingException cce) {
// If this happens, then some other encoding error occured
throw wrapper.ctbConverterFailure( cce ) ;
}
}
}
/**
* Special UTF16 converter which can either always write a BOM
* or use a specified byte order without one.
*/
private class UTF16CTBConverter extends JavaCTBConverter
{
// Using this constructor, we will always write a BOM
public UTF16CTBConverter() {
super(OSFCodeSetRegistry.UTF_16, 2);
}
// Using this constructor, we don't use a BOM and use the
// byte order specified
public UTF16CTBConverter(boolean littleEndian) {
super(littleEndian ?
OSFCodeSetRegistry.UTF_16LE :
OSFCodeSetRegistry.UTF_16BE,
2);
}
}
/**
* Implementation of BTCConverter which uses a sun.io.ByteToCharConverter
* for the real work. Handles translation of exceptions to the
* appropriate CORBA versions.
*/
private class JavaBTCConverter extends BTCConverter
{
private ORBUtilSystemException wrapper = ORBUtilSystemException.get(
CORBALogDomains.RPC_ENCODING ) ;
private OMGSystemException omgWrapper = OMGSystemException.get(
CORBALogDomains.RPC_ENCODING ) ;
protected CharsetDecoder btc;
private char[] buffer;
private int resultingNumChars;
private OSFCodeSetRegistry.Entry codeset;
public JavaBTCConverter(OSFCodeSetRegistry.Entry codeset) {
// Obtain a Decoder
btc = this.getConverter(codeset.getName());
this.codeset = codeset;
}
public final boolean isFixedWidthEncoding() {
return codeset.isFixedWidth();
}
// Should only be called if isFixedWidthEncoding is true
// IMPORTANT: This calls OSFCodeSetRegistry.Entry, not
// CharsetDecoder.maxCharsPerByte().
public final int getFixedCharWidth() {
return codeset.getMaxBytesPerChar();
}
public final int getNumChars() {
return resultingNumChars;
}
public char[] getChars(byte[] bytes, int offset, int numBytes) {
// Possible optimization of reading directly from the CDR
// byte buffer. The sun.io converter supposedly can handle
// incremental conversions in which a char is broken across
// two convert calls.
//
// Basic tests didn't show more than a 1 ms increase
// worst case. It's less than a factor of 2 increase.
// Also makes the interface more difficult.
try {
ByteBuffer byteBuf = ByteBuffer.wrap(bytes, offset, numBytes);
CharBuffer charBuf = btc.decode(byteBuf);
// CharBuffer returned by the decoder will set its limit
// to byte immediately after the last written byte.
resultingNumChars = charBuf.limit();
// IMPORTANT - It's possible the underlying char[] in the
// CharBuffer returned by btc.decode(byteBuf)
// is longer in length than the number of characters
// decoded. Hence, the check below to ensure the
// char[] returned contains all the chars that have
// been decoded and no more.
if (charBuf.limit() == charBuf.capacity()) {
buffer = charBuf.array();
} else {
buffer = new char[charBuf.limit()];
charBuf.get(buffer, 0, charBuf.limit()).position(0);
}
return buffer;
} catch (IllegalStateException ile) {
// There were a decoding operation already in progress
throw wrapper.btcConverterFailure( ile ) ;
} catch (MalformedInputException mie) {
// There were illegal Unicode char pairs
throw wrapper.badUnicodePair( mie ) ;
} catch (UnmappableCharacterException uce) {
// A character doesn't map to the desired code set.
// CORBA formal 00-11-03.
throw omgWrapper.charNotInCodeset( uce ) ;
} catch (CharacterCodingException cce) {
// If this happens, then a character decoding error occured.
throw wrapper.btcConverterFailure( cce ) ;
}
}
/**
* Utility method to find a CharsetDecoder in the
* cache or create a new one if necessary. Throws an
* INTERNAL if the code set is unknown.
*/
protected CharsetDecoder getConverter(String javaCodeSetName) {
CharsetDecoder result = null;
try {
result = cache.getByteToCharConverter(javaCodeSetName);
if (result == null) {
Charset tmpCharset = Charset.forName(javaCodeSetName);
result = tmpCharset.newDecoder();
cache.setConverter(javaCodeSetName, result);
}
} catch(IllegalCharsetNameException icne) {
// This can only happen if one of our charset entries has
// an illegal name.
throw wrapper.invalidBtcConverterName( icne, javaCodeSetName ) ;
}
return result;
}
}
/**
* Special converter for UTF16 since it's required to optionally
* support a byte order marker while the internal Java converters
* either require it or require that it isn't there.
*
* The solution is to check for the byte order marker, and if we
* need to do something differently, switch internal converters.
*/
private class UTF16BTCConverter extends JavaBTCConverter
{
private boolean defaultToLittleEndian;
private boolean converterUsesBOM = true;
private static final char UTF16_BE_MARKER = (char) 0xfeff;
private static final char UTF16_LE_MARKER = (char) 0xfffe;
// When there isn't a byte order marker, used the byte
// order specified.
public UTF16BTCConverter(boolean defaultToLittleEndian) {
super(OSFCodeSetRegistry.UTF_16);
this.defaultToLittleEndian = defaultToLittleEndian;
}
public char[] getChars(byte[] bytes, int offset, int numBytes) {
if (hasUTF16ByteOrderMarker(bytes, offset, numBytes)) {
if (!converterUsesBOM)
switchToConverter(OSFCodeSetRegistry.UTF_16);
converterUsesBOM = true;
return super.getChars(bytes, offset, numBytes);
} else {
if (converterUsesBOM) {
if (defaultToLittleEndian)
switchToConverter(OSFCodeSetRegistry.UTF_16LE);
else
switchToConverter(OSFCodeSetRegistry.UTF_16BE);
converterUsesBOM = false;
}
return super.getChars(bytes, offset, numBytes);
}
}
/**
* Utility method for determining if a UTF-16 byte order marker is present.
*/
private boolean hasUTF16ByteOrderMarker(byte[] array, int offset, int length) {
// If there aren't enough bytes to represent the marker and data,
// return false.
if (length >= 4) {
int b1 = array[offset] & 0x00FF;
int b2 = array[offset + 1] & 0x00FF;
char marker = (char)((b1 << 8) | (b2 << 0));
return (marker == UTF16_BE_MARKER || marker == UTF16_LE_MARKER);
} else
return false;
}
/**
* The current solution for dealing with UTF-16 in CORBA
* is that if our sun.io converter requires byte order markers,
* and then we see a CORBA wstring/wchar without them, we
* switch to the sun.io converter that doesn't require them.
*/
private void switchToConverter(OSFCodeSetRegistry.Entry newCodeSet) {
// Use the getConverter method from our superclass.
btc = super.getConverter(newCodeSet.getName());
}
}
/**
* CTB converter factory for single byte or variable length encodings.
*/
public CTBConverter getCTBConverter(OSFCodeSetRegistry.Entry codeset) {
int alignment = (!codeset.isFixedWidth() ?
1 :
codeset.getMaxBytesPerChar());
return new JavaCTBConverter(codeset, alignment);
}
/**
* CTB converter factory for multibyte (mainly fixed) encodings.
*
* Because of the awkwardness with byte order markers and the possibility of
* using UCS-2, you must specify both the endianness of the stream as well as
* whether or not to use byte order markers if applicable. UCS-2 has no byte
* order markers. UTF-16 has optional markers.
*
* If you select useByteOrderMarkers, there is no guarantee that the encoding
* will use the endianness specified.
*
*/
public CTBConverter getCTBConverter(OSFCodeSetRegistry.Entry codeset,
boolean littleEndian,
boolean useByteOrderMarkers) {
// UCS2 doesn't have byte order markers, and we're encoding it
// as UTF-16 since UCS2 isn't available in all Java platforms.
// They should be identical with only minor differences in
// negative cases.
if (codeset == OSFCodeSetRegistry.UCS_2)
return new UTF16CTBConverter(littleEndian);
// We can write UTF-16 with or without a byte order marker.
if (codeset == OSFCodeSetRegistry.UTF_16) {
if (useByteOrderMarkers)
return new UTF16CTBConverter();
else
return new UTF16CTBConverter(littleEndian);
}
// Everything else uses the generic JavaCTBConverter.
//
// Variable width encodings are aligned on 1 byte boundaries.
// A fixed width encoding with a max. of 4 bytes/char should
// align on a 4 byte boundary. Note that UTF-16 is a special
// case because of the optional byte order marker, so it's
// handled above.
//
// This doesn't matter for GIOP 1.2 wchars and wstrings
// since the encoded bytes are treated as an encapsulation.
int alignment = (!codeset.isFixedWidth() ?
1 :
codeset.getMaxBytesPerChar());
return new JavaCTBConverter(codeset, alignment);
}
/**
* BTCConverter factory for single byte or variable width encodings.
*/
public BTCConverter getBTCConverter(OSFCodeSetRegistry.Entry codeset) {
return new JavaBTCConverter(codeset);
}
/**
* BTCConverter factory for fixed width multibyte encodings.
*/
public BTCConverter getBTCConverter(OSFCodeSetRegistry.Entry codeset,
boolean defaultToLittleEndian) {
if (codeset == OSFCodeSetRegistry.UTF_16 ||
codeset == OSFCodeSetRegistry.UCS_2) {
return new UTF16BTCConverter(defaultToLittleEndian);
} else {
return new JavaBTCConverter(codeset);
}
}
/**
* Follows the code set negotiation algorithm in CORBA formal 99-10-07 13.7.2.
*
* Returns the proper negotiated OSF character encoding number or
* CodeSetConversion.FALLBACK_CODESET.
*/
private int selectEncoding(CodeSetComponentInfo.CodeSetComponent client,
CodeSetComponentInfo.CodeSetComponent server) {
// A "null" value for the server's nativeCodeSet means that
// the server desired not to indicate one. We'll take that
// to mean that it wants the first thing in its conversion list.
// If it's conversion list is empty, too, then use the fallback
// codeset.
int serverNative = server.nativeCodeSet;
if (serverNative == 0) {
if (server.conversionCodeSets.length > 0)
serverNative = server.conversionCodeSets[0];
else
return CodeSetConversion.FALLBACK_CODESET;
}
if (client.nativeCodeSet == serverNative) {
// Best case -- client and server don't have to convert
return serverNative;
}
// Is this client capable of converting to the server's
// native code set?
for (int i = 0; i < client.conversionCodeSets.length; i++) {
if (serverNative == client.conversionCodeSets[i]) {
// The client will convert to the server's
// native code set.
return serverNative;
}
}
// Is the server capable of converting to the client's
// native code set?
for (int i = 0; i < server.conversionCodeSets.length; i++) {
if (client.nativeCodeSet == server.conversionCodeSets[i]) {
// The server will convert to the client's
// native code set.
return client.nativeCodeSet;
}
}
// See if there are any code sets that both the server and client
// support (giving preference to the server). The order
// of conversion sets is from most to least desired.
for (int i = 0; i < server.conversionCodeSets.length; i++) {
for (int y = 0; y < client.conversionCodeSets.length; y++) {
if (server.conversionCodeSets[i] == client.conversionCodeSets[y]) {
return server.conversionCodeSets[i];
}
}
}
// Before using the fallback codesets, the spec calls for a
// compatibility check on the native code sets. It doesn't make
// sense because loss free communication is always possible with
// UTF8 and UTF16, the fall back code sets. It's also a lot
// of work to implement. In the case of incompatibility, the
// spec says to throw a CODESET_INCOMPATIBLE exception.
// Use the fallback
return CodeSetConversion.FALLBACK_CODESET;
}
/**
* Perform the code set negotiation algorithm and come up with
* the two encodings to use.
*/
public CodeSetComponentInfo.CodeSetContext negotiate(CodeSetComponentInfo client,
CodeSetComponentInfo server) {
int charData
= selectEncoding(client.getCharComponent(),
server.getCharComponent());
if (charData == CodeSetConversion.FALLBACK_CODESET) {
charData = OSFCodeSetRegistry.UTF_8.getNumber();
}
int wcharData
= selectEncoding(client.getWCharComponent(),
server.getWCharComponent());
if (wcharData == CodeSetConversion.FALLBACK_CODESET) {
wcharData = OSFCodeSetRegistry.UTF_16.getNumber();
}
return new CodeSetComponentInfo.CodeSetContext(charData,
wcharData);
}
// No one should instantiate a CodeSetConversion but the singleton
// instance method
private CodeSetConversion() {}
// initialize-on-demand holder
private static class CodeSetConversionHolder {
static final CodeSetConversion csc = new CodeSetConversion() ;
}
/**
* CodeSetConversion is a singleton, and this is the access point.
*/
public final static CodeSetConversion impl() {
return CodeSetConversionHolder.csc ;
}
// Singleton instance
private static CodeSetConversion implementation;
// Number used internally to indicate the fallback code
// set.
private static final int FALLBACK_CODESET = 0;
// Provides a thread local cache for the sun.io
// converters.
private CodeSetCache cache = new CodeSetCache();
}
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