org.openmdx.kernel.xml.AdaptiveInputStreamReader Maven / Gradle / Ivy
/*
* ====================================================================
* Project: openmdx, http://www.openmdx.org/
* Description: Adaptive InputStream Reader
* Owner: OMEX AG, Switzerland, http://www.omex.ch
* ====================================================================
*
* This software is published under the BSD license as listed below.
*
* Copyright (c) 2005-2013, OMEX AG, Switzerland
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* * Neither the name of the openMDX team nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* ------------------
*
* This product includes or is based on software developed by other
* organizations as listed in the NOTICE file.
*/
package org.openmdx.kernel.xml;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* The Adaptive Input Stream Reader has the following encoding priorities
* - The constructor's
encoding argument
* - A byte order mark
*
- An XML declaration's encoding attribute
*
- The platform's default encoding
*
*/
public class AdaptiveInputStreamReader extends Reader {
/**
* Constructor
*
* @param in
* @param encoding overrides the adaptive encoding unless it is null
* @param byteOrderMarkAware
* @param xmlDeclarationAware
* @param propagateClose tells whether a close request is propagated to the input stream
* @throws IOException
*/
public AdaptiveInputStreamReader(
InputStream in,
String overriddenEncoding,
boolean byteOrderMarkAware,
boolean xmlDeclarationAware,
boolean propagateClose
) throws IOException {
String encoding = overriddenEncoding;
if(byteOrderMarkAware || xmlDeclarationAware){
InputStream stream = new BufferedInputStream(in);
if (byteOrderMarkAware){
String byteOrderMark = ByteOrderMark.readByteOrderMark(stream);
if(encoding == null) {
encoding = byteOrderMark;
}
}
if(xmlDeclarationAware) {
if(encoding == null) {
XMLDeclaration xmlDeclaration = XMLDeclaration.readXMLDeclaration(
stream
);
if(xmlDeclaration != null) {
encoding = xmlDeclaration.getEncoding();
}
this.delegate = new BufferedReader(
encoding == null ? new InputStreamReader(stream) : new InputStreamReader(stream, encoding)
);
} else {
XMLDeclaration.readXMLDeclaration(
this.delegate = new BufferedReader(
new InputStreamReader(stream, encoding)
)
);
}
} else {
this.delegate = new BufferedReader(
encoding == null ? new InputStreamReader(in) : new InputStreamReader(in, encoding)
);
}
} else {
this.delegate = new BufferedReader(
encoding == null ? new InputStreamReader(in) : new InputStreamReader(in, encoding)
);
}
this.propagateClose = propagateClose;
}
/**
* The delegate, unless the stream is closed
*/
private Reader delegate;
/**
* Tells whether close operations shall be propagated to the underlying stream
*/
private final boolean propagateClose;
/**
* Ensure that the Reader is open
*
* @throws IOException
*/
private final Reader getDelegate(
) throws IOException{
if(this.delegate == null) {
throw new IOException("The reader is already closed");
}
return this.delegate;
}
/* (non-Javadoc)
* @see java.io.Reader#mark(int)
*/
@Override
public void mark(int readAheadLimit) throws IOException {
getDelegate().mark(readAheadLimit);
}
/* (non-Javadoc)
* @see java.io.Reader#markSupported()
*/
@Override
public boolean markSupported() {
return this.delegate != null && this.delegate.markSupported();
}
/* (non-Javadoc)
* @see java.io.Reader#read()
*/
@Override
public int read() throws IOException {
return getDelegate().read();
}
/* (non-Javadoc)
* @see java.io.Reader#read(char[], int, int)
*/
@Override
public int read(char[] cbuf, int off, int len) throws IOException {
return getDelegate().read(cbuf, off, len);
}
/* (non-Javadoc)
* @see java.io.Reader#read(char[])
*/
@Override
public int read(char[] cbuf) throws IOException {
return getDelegate().read(cbuf);
}
/* (non-Javadoc)
* @see java.io.Reader#ready()
*/
@Override
public boolean ready() throws IOException {
return getDelegate().ready();
}
/* (non-Javadoc)
* @see java.io.Reader#reset()
*/
@Override
public void reset() throws IOException {
getDelegate().reset();
}
/* (non-Javadoc)
* @see java.io.Reader#skip(long)
*/
@Override
public long skip(long n) throws IOException {
return getDelegate().skip(n);
}
/* (non-Javadoc)
* @see java.io.Reader#close()
*/
@Override
public void close() throws IOException {
if(this.delegate != null) {
if(this.propagateClose) {
this.delegate.close();
}
this.delegate = null;
}
}
//------------------------------------------------------------------------
// Class XMLDeclaration
//------------------------------------------------------------------------
/**
* XML Declaration
*/
protected static final class XMLDeclaration {
/**
* Constructor
*/
protected XMLDeclaration(
){
super();
}
/**
* Constructor
*/
protected XMLDeclaration(
String version,
String encoding,
String standalone
) {
this.version = version;
this.encoding = encoding;
this.standalone = standalone;
}
/**
* Constructor
*/
public XMLDeclaration(
XMLDeclaration that
) {
this(
that.version,
that.encoding,
that.standalone
);
}
/**
* The mandatory XML version attribute
*/
private String version;
/**
* The optional encoding attribute
*/
private String encoding;
/**
* The optional standalone attribute
*/
private String standalone;
/**
* Maximal number of characters to read ahead.
*/
static final int READ_AHEAD_LIMIT = 100;
/**
*
*/
private static final Pattern XML_DECLARATION_PATTERN;
/**
* @return Returns the encoding.
*/
public String getEncoding() {
return
Encodings.ISO_8859_1.equals(this.encoding) ?
"ISO-8859-1" :
Encodings.UTF_16BE.equals(this.encoding) ||
Encodings.UTF_16BE_WITH_BOM.equals(this.encoding) ?
"UTF-16BE" :
Encodings.UTF_16LE.equals(this.encoding) ||
Encodings.UTF_16LE_WITH_BOM.equals(this.encoding) ?
"UTF-16LE" :
Encodings.UTF_8.equals(this.encoding) ?
"UTF-8" :
Encodings.WINDOWS_1252.equals(this.encoding) ?
"windows-1252" :
this.encoding;
}
/**
* @param encoding The encoding to set.
*/
public void setQuotedEncoding(String encoding) {
this.encoding = unquote(encoding);
}
/**
* @return Returns the standalone.
*/
public String getStandalone() {
return standalone;
}
/**
* @param standalone The standalone to set.
*/
public void setQuotedStandalone(String standalone) {
this.standalone = unquote(standalone);
}
/**
* @param version The version to set.
*/
public void setQuotedVersion(String version) {
this.version = unquote(version);
}
/**
* @return Returns the version.
*/
public String getVersion() {
return version;
}
/**
* Remove the suurounding «'» respectively «"»
* characters.
*
* @param quoted the embedded string; may be null
* @return the quoted string without its leading or trailing character;
* or null if quoted was null.
*/
private static final String unquote(
String quoted
){
return quoted == null || quoted.length() < 2 ?
null :
quoted.substring(1, quoted.length() - 1);
}
/**
* Consume the XML Declaration and return it or reset the stream otherwise.
*
* @param in the stream
* @param regexpFactory
*
* @return the XML Declaration; or null if none has been
* specified.
*
* @throws IOException
*/
public static XMLDeclaration readXMLDeclaration(
InputStream in
) throws IOException {
return readXMLDeclaration(
new ASCIIReader(in)
);
}
/**
* Consume the XML Declaration and return it or reset the stream otherwise.
*
* @param in the stream
* @param regexpFactory TODO
*
* @return the XML Declaration; or null if none has been
* specified.
*
* @throws IOException
*/
public static XMLDeclaration readXMLDeclaration(
Reader in
) throws IOException {
in.mark(READ_AHEAD_LIMIT);
try {
if(
in.read() == '<' &&
in.read() == '?' &&
in.read() == 'x' &&
in.read() == 'm' &&
in.read() == 'l'
){
StringBuffer b = new StringBuffer();
xmlDeclaration: for(
int i = 5, c = in.read();
c > 0 && i++ < READ_AHEAD_LIMIT;
c = in.read()
){
if(c == '>'){
Matcher matcher = XML_DECLARATION_PATTERN.matcher(b.toString());
if(!matcher.matches()) break xmlDeclaration;
XMLDeclaration reply = new XMLDeclaration();
reply.setQuotedVersion(matcher.group(1));
reply.setQuotedEncoding(matcher.group(3));
reply.setQuotedStandalone(matcher.group(5));
return reply;
} else {
b.append((char)c);
}
}
}
in.reset();
return null;
} catch (IOException exception) {
in.reset();
throw exception;
} catch (RuntimeException exception) {
in.reset();
throw exception;
}
}
//------------------------------------------------------------------------
// Extends Object
//------------------------------------------------------------------------
/* (non-Javadoc)
* @see java.lang.Object#toString()
*/
@Override
public String toString() {
StringBuffer b = new StringBuffer(
""
).toString();
}
static {
String whitespace = "[ \n\r\t]";
String optionalWhitespace = whitespace + '*';
String mandatoryWhitespace = whitespace + '+';
String value = optionalWhitespace + "=" + optionalWhitespace +
"('[^']*'|\"[^\"]*\")";
XML_DECLARATION_PATTERN = Pattern.compile(
"^" +
mandatoryWhitespace + "version" + value + "(" +
mandatoryWhitespace + "encoding" + value + ")?(" +
mandatoryWhitespace + "standalone" + value + ")?" +
optionalWhitespace + "\\?$"
);
}
}
//------------------------------------------------------------------------
// Class ASICCReader
//------------------------------------------------------------------------
/**
* ASCII Reader
*
* This InputStream Reader is able to read ASCII
* characters encoded in any of the following formats provided the stream
* does not contain a byte order mark or any other non-ASCII character up
* the position it is read through the InputStreamASCIIReader.
*
* - US-ASCII
*
- ISO-8859-1
*
- UTF-8
*
- UTF-16
*
- UTF-32
*
* The InputStreamASCIIReader is designed not to read ahead.
*/
protected static class ASCIIReader extends Reader {
/**
* Constructor
*
* @param source
*/
protected ASCIIReader(
InputStream in
) {
this.in = in;
}
/**
*
*/
protected InputStream in;
/**
*
*/
private int prefix0 = -1;
/**
*
*/
private int suffix0 = -1;
/**
* Close disconnects the reader from the underlying
* InputStream rather than closing it.
*
* @exception IOException
*/
@Override
public void close() throws IOException {
this.in = null;
}
/* (non-Javadoc)
* @see java.io.Reader#read(char[], int, int)
*/
@Override
public int read(
char[] cbuf,
int off,
int len
) throws IOException {
for(
int i = 0;
i < len;
i++
){
int c = read();
if(c < 0) return i == 0 ? -1 : i;
cbuf[i + off] = (char) c;
}
return len;
}
/* (non-Javadoc)
* @see java.io.Reader#read()
*/
@Override
public int read(
) throws IOException {
if(isEncodingKnown()){
for(int i = prefix0; i > 0; i--) this.in.read();
int c = this.in.read();
for(int i = suffix0; i > 0; i--) this.in.read();
return c > 127 ? 0 : c;
} else if (prefix0 < 0) { // prefix0 unkown
for(
int i = 0;
i < 4;
i++
){
int c = this.in.read();
if(c != 0) {
this.prefix0 = i;
if(i > 0) this.suffix0 = 0;
return c;
}
}
} else { // suffix0 unknown
for(
int i = 0;
i < 4;
i++
){
int c = this.in.read();
if(c != 0) {
this.suffix0 = i;
return c;
}
}
}
return 0;
}
/**
* Tells whether the encoding is already konwn
*
* @return true if the encoding is already konwn
*/
private boolean isEncodingKnown(){
return prefix0 >= 0 && suffix0 >= 0;
}
/**
* Determine the maximal number of bytes per character
*
* @return the maximal number of bytes per character
*/
private int maxBytesPerCharacter(
){
return isEncodingKnown() ? 1 + prefix0 + suffix0 : 4;
}
/* (non-Javadoc)
* @see java.io.Reader#mark(int)
*/
@Override
public void mark(int readAheadLimit) throws IOException {
this.in.mark(
readAheadLimit * maxBytesPerCharacter()
);
}
/* (non-Javadoc)
* @see java.io.Reader#markSupported()
*/
@Override
public boolean markSupported() {
return this.in.markSupported();
}
/* (non-Javadoc)
* @see java.io.Reader#reset()
*/
@Override
public void reset() throws IOException {
this.in.reset();
}
}
//------------------------------------------------------------------------
// Class Encodings
//------------------------------------------------------------------------
/**
* Canonical Encoding Names for java.io and
* java.lang API.
*/
protected static class Encodings {
/**
* Eight-bit UCS Transformation Format
*
* @since JRE 1.2
*/
protected final static String UTF_8 = "UTF8";
/**
* American Standard Code for Information Interchange
*
* @since JRE 1.2
*/
protected final static String US_ASCII = "ASCII";
/**
* ISO 8859-1, Latin Alphabet No. 1
*
* @since JRE 1.2
*/
protected final static String ISO_8859_1 = "ISO8859_1";
/**
* Sixteen-bit Unicode Transformation Format, big-endian byte order, with byte-order mark
*
* @since JRE 1.2
*/
protected final static String UTF_16BE_WITH_BOM = "UnicodeBig";
/**
* Sixteen-bit Unicode Transformation Format, little-endian byte order, with byte-order mark
*
* @since JRE 1.2
*/
protected final static String UTF_16LE_WITH_BOM = "UnicodeLittle";
/**
* Windows Latin-1
*
* @since JRE 1.2
*/
protected final static String WINDOWS_1252 = "Cp1252";
/**
* Sixteen-bit Unicode Transformation Format, big-endian byte order
*
* @since JRE 1.3
*/
protected final static String UTF_16BE = "UnicodeBigUnmarked";
/**
* Sixteen-bit Unicode Transformation Format, little-endian byte order
*
* @since JRE 1.3
*/
protected final static String UTF_16LE = "UnicodeLittleUnmarked";
/**
* Sixteen-bit UCS Transformation Format, byte order identified by
* - a mandatory initial byte-order mark
* @since JRE 1.3
*
*
* - an optional byte-order mark
* @since JRE 1.4
*
*/
protected final static String UTF_16 = "UTF-16";
/**
* Thirtytwo-bit UCS Transformation Format, byte order identified by an optional byte-order mark.
*/
protected final static String UTF_32 = "UTF-32";
/**
* Thirtytwo-bit UCS Transformation Format, big-endian byte order
*/
protected final static String UTF_32BE = "UTF-32BE";
/**
* Thirtytwo-bit UCS Transformation Format, little-endian byte order
*/
protected final static String UTF_32LE = "UTF-32LE";
}
//------------------------------------------------------------------------
// Class ByteOrderMark
//------------------------------------------------------------------------
/**
* Byte Order Mark
*
* The exact bytes
* comprising the BOM will be whatever the Unicode character FEFF is
* converted into by that transformation format. In that form, the BOM
* serves to indicate both that it is a Unicode file, and which of the
* formats it is in. Examples:
*
*
*
*
* Bytes
* Encoding Form
*
*
* EF BB BF
* UTF-8
*
*
* 00 00 FE FF
* UTF-32, big-endian
*
*
* FF FE 00 00
* UTF-32, little-endian
*
*
* FE FF
* UTF-16, big-endian
*
*
* FF FE
* UTF-16, little-endian
*
*
*
*
*/
protected static class ByteOrderMark {
/**
* Constructor
*/
private ByteOrderMark() {
// Avoid instantiation
}
/**
* The Unicode character point used as byte order mark.
*/
public final static char VALUE = 0xFEFF;
/**
* Each ENCODINGS entry corresponds to a
* REPRESENTATIONS entry.
*/
final public static String[] ENCODINGS = {
Encodings.UTF_8,
Encodings.UTF_32BE,
Encodings.UTF_32LE,
Encodings.UTF_16BE,
Encodings.UTF_16LE
};
/**
* Each REPRESENTATIONS entry corresponds to an
* ENCODINGS entry.
*/
final public static byte[][] REPRESENTATIONS = new byte[][]{
new byte[]{(byte)0xEF, (byte)0xBB, (byte)0xBF},
new byte[]{(byte)0x00, (byte)0x00, (byte)0xFE, (byte)0xFF},
new byte[]{(byte)0xFF, (byte)0xFE, (byte)0x00, (byte)0x00},
new byte[]{(byte)0xFE, (byte)0xFF},
new byte[]{(byte)0xFF, (byte)0xFE}
};
/**
* Consume the input stream's byte order mark if any and return the
* corresponding encoding or reset the input stream otherwise.
*
* @param in the input stream
*
* @return the byte order mark's encoding; or null in absence
* of a byte order mark.
*
* @throws IOException
*/
public static String readByteOrderMark(
InputStream in
) throws IOException {
in.mark(4);
byte[] head = new byte[4];
int limit = in.read(head);
encodings: for(
int encoding = 0;
encoding < REPRESENTATIONS.length;
encoding++
){
byte[] bom = ByteOrderMark.REPRESENTATIONS[encoding];
if(limit < bom.length) continue encodings;
for(
int j = 0;
j < bom.length;
j++
) if(
bom[j] != head[j]
) continue encodings;
in.reset();
in.skip(bom.length);
return ByteOrderMark.ENCODINGS[encoding];
}
in.reset();
return null;
}
}
}
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