org.apache.commons.io.input.XmlStreamReader Maven / Gradle / Ivy
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.io.input;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StringReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.text.MessageFormat;
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.commons.io.ByteOrderMark;
/**
* Character stream that handles all the necessary Voodoo to figure out the
* charset encoding of the XML document within the stream.
*
* IMPORTANT: This class is not related in any way to the org.xml.sax.XMLReader.
* This one IS a character stream.
*
* All this has to be done without consuming characters from the stream, if not
* the XML parser will not recognized the document as a valid XML. This is not
* 100% true, but it's close enough (UTF-8 BOM is not handled by all parsers
* right now, XmlStreamReader handles it and things work in all parsers).
*
* The XmlStreamReader class handles the charset encoding of XML documents in
* Files, raw streams and HTTP streams by offering a wide set of constructors.
*
* By default the charset encoding detection is lenient, the constructor with
* the lenient flag can be used for a script (following HTTP MIME and XML
* specifications). All this is nicely explained by Mark Pilgrim in his blog,
* Determining the character encoding of a feed.
*
* Originally developed for ROME under
* Apache License 2.0.
*
* @see org.apache.commons.io.output.XmlStreamWriter
* @since 2.0
*/
public class XmlStreamReader extends Reader {
private static final int BUFFER_SIZE = 4096;
private static final String UTF_8 = "UTF-8";
private static final String US_ASCII = "US-ASCII";
private static final String UTF_16BE = "UTF-16BE";
private static final String UTF_16LE = "UTF-16LE";
private static final String UTF_32BE = "UTF-32BE";
private static final String UTF_32LE = "UTF-32LE";
private static final String UTF_16 = "UTF-16";
private static final String UTF_32 = "UTF-32";
private static final String EBCDIC = "CP1047";
private static final ByteOrderMark[] BOMS = new ByteOrderMark[] {
ByteOrderMark.UTF_8,
ByteOrderMark.UTF_16BE,
ByteOrderMark.UTF_16LE,
ByteOrderMark.UTF_32BE,
ByteOrderMark.UTF_32LE
};
// UTF_16LE and UTF_32LE have the same two starting BOM bytes.
private static final ByteOrderMark[] XML_GUESS_BYTES = new ByteOrderMark[] {
new ByteOrderMark(UTF_8, 0x3C, 0x3F, 0x78, 0x6D),
new ByteOrderMark(UTF_16BE, 0x00, 0x3C, 0x00, 0x3F),
new ByteOrderMark(UTF_16LE, 0x3C, 0x00, 0x3F, 0x00),
new ByteOrderMark(UTF_32BE, 0x00, 0x00, 0x00, 0x3C,
0x00, 0x00, 0x00, 0x3F, 0x00, 0x00, 0x00, 0x78, 0x00, 0x00, 0x00, 0x6D),
new ByteOrderMark(UTF_32LE, 0x3C, 0x00, 0x00, 0x00,
0x3F, 0x00, 0x00, 0x00, 0x78, 0x00, 0x00, 0x00, 0x6D, 0x00, 0x00, 0x00),
new ByteOrderMark(EBCDIC, 0x4C, 0x6F, 0xA7, 0x94)
};
private final Reader reader;
private final String encoding;
private final String defaultEncoding;
/**
* Returns the default encoding to use if none is set in HTTP content-type,
* XML prolog and the rules based on content-type are not adequate.
*
* If it is NULL the content-type based rules are used.
*
* @return the default encoding to use.
*/
public String getDefaultEncoding() {
return defaultEncoding;
}
/**
* Creates a Reader for a File.
*
* It looks for the UTF-8 BOM first, if none sniffs the XML prolog charset,
* if this is also missing defaults to UTF-8.
*
* It does a lenient charset encoding detection, check the constructor with
* the lenient parameter for details.
*
* @param file File to create a Reader from.
* @throws IOException thrown if there is a problem reading the file.
*/
public XmlStreamReader(final File file) throws IOException {
this(new FileInputStream(file));
}
/**
* Creates a Reader for a raw InputStream.
*
* It follows the same logic used for files.
*
* It does a lenient charset encoding detection, check the constructor with
* the lenient parameter for details.
*
* @param is InputStream to create a Reader from.
* @throws IOException thrown if there is a problem reading the stream.
*/
public XmlStreamReader(final InputStream is) throws IOException {
this(is, true);
}
/**
* Creates a Reader for a raw InputStream.
*
* It follows the same logic used for files.
*
* If lenient detection is indicated and the detection above fails as per
* specifications it then attempts the following:
*
* If the content type was 'text/html' it replaces it with 'text/xml' and
* tries the detection again.
*
* Else if the XML prolog had a charset encoding that encoding is used.
*
* Else if the content type had a charset encoding that encoding is used.
*
* Else 'UTF-8' is used.
*
* If lenient detection is indicated an XmlStreamReaderException is never
* thrown.
*
* @param is InputStream to create a Reader from.
* @param lenient indicates if the charset encoding detection should be
* relaxed.
* @throws IOException thrown if there is a problem reading the stream.
* @throws XmlStreamReaderException thrown if the charset encoding could not
* be determined according to the specs.
*/
public XmlStreamReader(final InputStream is, final boolean lenient) throws IOException {
this(is, lenient, null);
}
/**
* Creates a Reader for a raw InputStream.
*
* It follows the same logic used for files.
*
* If lenient detection is indicated and the detection above fails as per
* specifications it then attempts the following:
*
* If the content type was 'text/html' it replaces it with 'text/xml' and
* tries the detection again.
*
* Else if the XML prolog had a charset encoding that encoding is used.
*
* Else if the content type had a charset encoding that encoding is used.
*
* Else 'UTF-8' is used.
*
* If lenient detection is indicated an XmlStreamReaderException is never
* thrown.
*
* @param is InputStream to create a Reader from.
* @param lenient indicates if the charset encoding detection should be
* relaxed.
* @param defaultEncoding The default encoding
* @throws IOException thrown if there is a problem reading the stream.
* @throws XmlStreamReaderException thrown if the charset encoding could not
* be determined according to the specs.
*/
public XmlStreamReader(final InputStream is, final boolean lenient, final String defaultEncoding)
throws IOException {
this.defaultEncoding = defaultEncoding;
final BOMInputStream bom = new BOMInputStream(new BufferedInputStream(is, BUFFER_SIZE), false, BOMS);
final BOMInputStream pis = new BOMInputStream(bom, true, XML_GUESS_BYTES);
this.encoding = doRawStream(bom, pis, lenient);
this.reader = new InputStreamReader(pis, encoding);
}
/**
* Creates a Reader using the InputStream of a URL.
*
* If the URL is not of type HTTP and there is not 'content-type' header in
* the fetched data it uses the same logic used for Files.
*
* If the URL is a HTTP Url or there is a 'content-type' header in the
* fetched data it uses the same logic used for an InputStream with
* content-type.
*
* It does a lenient charset encoding detection, check the constructor with
* the lenient parameter for details.
*
* @param url URL to create a Reader from.
* @throws IOException thrown if there is a problem reading the stream of
* the URL.
*/
public XmlStreamReader(final URL url) throws IOException {
this(url.openConnection(), null);
}
/**
* Creates a Reader using the InputStream of a URLConnection.
*
* If the URLConnection is not of type HttpURLConnection and there is not
* 'content-type' header in the fetched data it uses the same logic used for
* files.
*
* If the URLConnection is a HTTP Url or there is a 'content-type' header in
* the fetched data it uses the same logic used for an InputStream with
* content-type.
*
* It does a lenient charset encoding detection, check the constructor with
* the lenient parameter for details.
*
* @param conn URLConnection to create a Reader from.
* @param defaultEncoding The default encoding
* @throws IOException thrown if there is a problem reading the stream of
* the URLConnection.
*/
public XmlStreamReader(final URLConnection conn, final String defaultEncoding) throws IOException {
this.defaultEncoding = defaultEncoding;
final boolean lenient = true;
final String contentType = conn.getContentType();
final InputStream is = conn.getInputStream();
final BOMInputStream bom = new BOMInputStream(new BufferedInputStream(is, BUFFER_SIZE), false, BOMS);
final BOMInputStream pis = new BOMInputStream(bom, true, XML_GUESS_BYTES);
if (conn instanceof HttpURLConnection || contentType != null) {
this.encoding = doHttpStream(bom, pis, contentType, lenient);
} else {
this.encoding = doRawStream(bom, pis, lenient);
}
this.reader = new InputStreamReader(pis, encoding);
}
/**
* Creates a Reader using an InputStream and the associated content-type
* header.
*
* First it checks if the stream has BOM. If there is not BOM checks the
* content-type encoding. If there is not content-type encoding checks the
* XML prolog encoding. If there is not XML prolog encoding uses the default
* encoding mandated by the content-type MIME type.
*
* It does a lenient charset encoding detection, check the constructor with
* the lenient parameter for details.
*
* @param is InputStream to create the reader from.
* @param httpContentType content-type header to use for the resolution of
* the charset encoding.
* @throws IOException thrown if there is a problem reading the file.
*/
public XmlStreamReader(final InputStream is, final String httpContentType)
throws IOException {
this(is, httpContentType, true);
}
/**
* Creates a Reader using an InputStream and the associated content-type
* header. This constructor is lenient regarding the encoding detection.
*
* First it checks if the stream has BOM. If there is not BOM checks the
* content-type encoding. If there is not content-type encoding checks the
* XML prolog encoding. If there is not XML prolog encoding uses the default
* encoding mandated by the content-type MIME type.
*
* If lenient detection is indicated and the detection above fails as per
* specifications it then attempts the following:
*
* If the content type was 'text/html' it replaces it with 'text/xml' and
* tries the detection again.
*
* Else if the XML prolog had a charset encoding that encoding is used.
*
* Else if the content type had a charset encoding that encoding is used.
*
* Else 'UTF-8' is used.
*
* If lenient detection is indicated an XmlStreamReaderException is never
* thrown.
*
* @param is InputStream to create the reader from.
* @param httpContentType content-type header to use for the resolution of
* the charset encoding.
* @param lenient indicates if the charset encoding detection should be
* relaxed.
* @param defaultEncoding The default encoding
* @throws IOException thrown if there is a problem reading the file.
* @throws XmlStreamReaderException thrown if the charset encoding could not
* be determined according to the specs.
*/
public XmlStreamReader(final InputStream is, final String httpContentType,
final boolean lenient, final String defaultEncoding) throws IOException {
this.defaultEncoding = defaultEncoding;
final BOMInputStream bom = new BOMInputStream(new BufferedInputStream(is, BUFFER_SIZE), false, BOMS);
final BOMInputStream pis = new BOMInputStream(bom, true, XML_GUESS_BYTES);
this.encoding = doHttpStream(bom, pis, httpContentType, lenient);
this.reader = new InputStreamReader(pis, encoding);
}
/**
* Creates a Reader using an InputStream and the associated content-type
* header. This constructor is lenient regarding the encoding detection.
*
* First it checks if the stream has BOM. If there is not BOM checks the
* content-type encoding. If there is not content-type encoding checks the
* XML prolog encoding. If there is not XML prolog encoding uses the default
* encoding mandated by the content-type MIME type.
*
* If lenient detection is indicated and the detection above fails as per
* specifications it then attempts the following:
*
* If the content type was 'text/html' it replaces it with 'text/xml' and
* tries the detection again.
*
* Else if the XML prolog had a charset encoding that encoding is used.
*
* Else if the content type had a charset encoding that encoding is used.
*
* Else 'UTF-8' is used.
*
* If lenient detection is indicated an XmlStreamReaderException is never
* thrown.
*
* @param is InputStream to create the reader from.
* @param httpContentType content-type header to use for the resolution of
* the charset encoding.
* @param lenient indicates if the charset encoding detection should be
* relaxed.
* @throws IOException thrown if there is a problem reading the file.
* @throws XmlStreamReaderException thrown if the charset encoding could not
* be determined according to the specs.
*/
public XmlStreamReader(final InputStream is, final String httpContentType,
final boolean lenient) throws IOException {
this(is, httpContentType, lenient, null);
}
/**
* Returns the charset encoding of the XmlStreamReader.
*
* @return charset encoding.
*/
public String getEncoding() {
return encoding;
}
/**
* Invokes the underlying reader's read(char[], int, int) method.
* @param buf the buffer to read the characters into
* @param offset The start offset
* @param len The number of bytes to read
* @return the number of characters read or -1 if the end of stream
* @throws IOException if an I/O error occurs
*/
@Override
public int read(final char[] buf, final int offset, final int len) throws IOException {
return reader.read(buf, offset, len);
}
/**
* Closes the XmlStreamReader stream.
*
* @throws IOException thrown if there was a problem closing the stream.
*/
@Override
public void close() throws IOException {
reader.close();
}
/**
* Process the raw stream.
*
* @param bom BOMInputStream to detect byte order marks
* @param pis BOMInputStream to guess XML encoding
* @param lenient indicates if the charset encoding detection should be
* relaxed.
* @return the encoding to be used
* @throws IOException thrown if there is a problem reading the stream.
*/
private String doRawStream(final BOMInputStream bom, final BOMInputStream pis, final boolean lenient)
throws IOException {
final String bomEnc = bom.getBOMCharsetName();
final String xmlGuessEnc = pis.getBOMCharsetName();
final String xmlEnc = getXmlProlog(pis, xmlGuessEnc);
try {
return calculateRawEncoding(bomEnc, xmlGuessEnc, xmlEnc);
} catch (final XmlStreamReaderException ex) {
if (lenient) {
return doLenientDetection(null, ex);
}
throw ex;
}
}
/**
* Process a HTTP stream.
*
* @param bom BOMInputStream to detect byte order marks
* @param pis BOMInputStream to guess XML encoding
* @param httpContentType The HTTP content type
* @param lenient indicates if the charset encoding detection should be
* relaxed.
* @return the encoding to be used
* @throws IOException thrown if there is a problem reading the stream.
*/
private String doHttpStream(final BOMInputStream bom, final BOMInputStream pis, final String httpContentType,
final boolean lenient) throws IOException {
final String bomEnc = bom.getBOMCharsetName();
final String xmlGuessEnc = pis.getBOMCharsetName();
final String xmlEnc = getXmlProlog(pis, xmlGuessEnc);
try {
return calculateHttpEncoding(httpContentType, bomEnc,
xmlGuessEnc, xmlEnc, lenient);
} catch (final XmlStreamReaderException ex) {
if (lenient) {
return doLenientDetection(httpContentType, ex);
}
throw ex;
}
}
/**
* Do lenient detection.
*
* @param httpContentType content-type header to use for the resolution of
* the charset encoding.
* @param ex The thrown exception
* @return the encoding
* @throws IOException thrown if there is a problem reading the stream.
*/
private String doLenientDetection(String httpContentType,
XmlStreamReaderException ex) throws IOException {
if (httpContentType != null && httpContentType.startsWith("text/html")) {
httpContentType = httpContentType.substring("text/html".length());
httpContentType = "text/xml" + httpContentType;
try {
return calculateHttpEncoding(httpContentType, ex.getBomEncoding(),
ex.getXmlGuessEncoding(), ex.getXmlEncoding(), true);
} catch (final XmlStreamReaderException ex2) {
ex = ex2;
}
}
String encoding = ex.getXmlEncoding();
if (encoding == null) {
encoding = ex.getContentTypeEncoding();
}
if (encoding == null) {
encoding = defaultEncoding == null ? UTF_8 : defaultEncoding;
}
return encoding;
}
/**
* Calculate the raw encoding.
*
* @param bomEnc BOM encoding
* @param xmlGuessEnc XML Guess encoding
* @param xmlEnc XML encoding
* @return the raw encoding
* @throws IOException thrown if there is a problem reading the stream.
*/
String calculateRawEncoding(final String bomEnc, final String xmlGuessEnc,
final String xmlEnc) throws IOException {
// BOM is Null
if (bomEnc == null) {
if (xmlGuessEnc == null || xmlEnc == null) {
return defaultEncoding == null ? UTF_8 : defaultEncoding;
}
if (xmlEnc.equals(UTF_16) &&
(xmlGuessEnc.equals(UTF_16BE) || xmlGuessEnc.equals(UTF_16LE))) {
return xmlGuessEnc;
}
return xmlEnc;
}
// BOM is UTF-8
if (bomEnc.equals(UTF_8)) {
if (xmlGuessEnc != null && !xmlGuessEnc.equals(UTF_8)) {
final String msg = MessageFormat.format(RAW_EX_1, bomEnc, xmlGuessEnc, xmlEnc);
throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
}
if (xmlEnc != null && !xmlEnc.equals(UTF_8)) {
final String msg = MessageFormat.format(RAW_EX_1, bomEnc, xmlGuessEnc, xmlEnc);
throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
}
return bomEnc;
}
// BOM is UTF-16BE or UTF-16LE
if (bomEnc.equals(UTF_16BE) || bomEnc.equals(UTF_16LE)) {
if (xmlGuessEnc != null && !xmlGuessEnc.equals(bomEnc)) {
final String msg = MessageFormat.format(RAW_EX_1, bomEnc, xmlGuessEnc, xmlEnc);
throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
}
if (xmlEnc != null && !xmlEnc.equals(UTF_16) && !xmlEnc.equals(bomEnc)) {
final String msg = MessageFormat.format(RAW_EX_1, bomEnc, xmlGuessEnc, xmlEnc);
throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
}
return bomEnc;
}
// BOM is UTF-32BE or UTF-32LE
if (bomEnc.equals(UTF_32BE) || bomEnc.equals(UTF_32LE)) {
if (xmlGuessEnc != null && !xmlGuessEnc.equals(bomEnc)) {
final String msg = MessageFormat.format(RAW_EX_1, bomEnc, xmlGuessEnc, xmlEnc);
throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
}
if (xmlEnc != null && !xmlEnc.equals(UTF_32) && !xmlEnc.equals(bomEnc)) {
final String msg = MessageFormat.format(RAW_EX_1, bomEnc, xmlGuessEnc, xmlEnc);
throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
}
return bomEnc;
}
// BOM is something else
final String msg = MessageFormat.format(RAW_EX_2, bomEnc, xmlGuessEnc, xmlEnc);
throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
}
/**
* Calculate the HTTP encoding.
*
* @param httpContentType The HTTP content type
* @param bomEnc BOM encoding
* @param xmlGuessEnc XML Guess encoding
* @param xmlEnc XML encoding
* @param lenient indicates if the charset encoding detection should be
* relaxed.
* @return the HTTP encoding
* @throws IOException thrown if there is a problem reading the stream.
*/
String calculateHttpEncoding(final String httpContentType,
final String bomEnc, final String xmlGuessEnc, final String xmlEnc,
final boolean lenient) throws IOException {
// Lenient and has XML encoding
if (lenient && xmlEnc != null) {
return xmlEnc;
}
// Determine mime/encoding content types from HTTP Content Type
final String cTMime = getContentTypeMime(httpContentType);
final String cTEnc = getContentTypeEncoding(httpContentType);
final boolean appXml = isAppXml(cTMime);
final boolean textXml = isTextXml(cTMime);
// Mime type NOT "application/xml" or "text/xml"
if (!appXml && !textXml) {
final String msg = MessageFormat.format(HTTP_EX_3, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
throw new XmlStreamReaderException(msg, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
}
// No content type encoding
if (cTEnc == null) {
if (appXml) {
return calculateRawEncoding(bomEnc, xmlGuessEnc, xmlEnc);
}
return defaultEncoding == null ? US_ASCII : defaultEncoding;
}
// UTF-16BE or UTF-16LE content type encoding
if (cTEnc.equals(UTF_16BE) || cTEnc.equals(UTF_16LE)) {
if (bomEnc != null) {
final String msg = MessageFormat.format(HTTP_EX_1, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
throw new XmlStreamReaderException(msg, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
}
return cTEnc;
}
// UTF-16 content type encoding
if (cTEnc.equals(UTF_16)) {
if (bomEnc != null && bomEnc.startsWith(UTF_16)) {
return bomEnc;
}
final String msg = MessageFormat.format(HTTP_EX_2, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
throw new XmlStreamReaderException(msg, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
}
// UTF-32BE or UTF-132E content type encoding
if (cTEnc.equals(UTF_32BE) || cTEnc.equals(UTF_32LE)) {
if (bomEnc != null) {
final String msg = MessageFormat.format(HTTP_EX_1, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
throw new XmlStreamReaderException(msg, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
}
return cTEnc;
}
// UTF-32 content type encoding
if (cTEnc.equals(UTF_32)) {
if (bomEnc != null && bomEnc.startsWith(UTF_32)) {
return bomEnc;
}
final String msg = MessageFormat.format(HTTP_EX_2, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
throw new XmlStreamReaderException(msg, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
}
return cTEnc;
}
/**
* Returns MIME type or NULL if httpContentType is NULL.
*
* @param httpContentType the HTTP content type
* @return The mime content type
*/
static String getContentTypeMime(final String httpContentType) {
String mime = null;
if (httpContentType != null) {
final int i = httpContentType.indexOf(";");
if (i >= 0) {
mime = httpContentType.substring(0, i);
} else {
mime = httpContentType;
}
mime = mime.trim();
}
return mime;
}
private static final Pattern CHARSET_PATTERN = Pattern
.compile("charset=[\"']?([.[^; \"']]*)[\"']?");
/**
* Returns charset parameter value, NULL if not present, NULL if
* httpContentType is NULL.
*
* @param httpContentType the HTTP content type
* @return The content type encoding (upcased)
*/
static String getContentTypeEncoding(final String httpContentType) {
String encoding = null;
if (httpContentType != null) {
final int i = httpContentType.indexOf(";");
if (i > -1) {
final String postMime = httpContentType.substring(i + 1);
final Matcher m = CHARSET_PATTERN.matcher(postMime);
encoding = m.find() ? m.group(1) : null;
encoding = encoding != null ? encoding.toUpperCase(Locale.ROOT) : null;
}
}
return encoding;
}
public static final Pattern ENCODING_PATTERN = Pattern.compile(
"<\\?xml.*encoding[\\s]*=[\\s]*((?:\".[^\"]*\")|(?:'.[^']*'))",
Pattern.MULTILINE);
/**
* Returns the encoding declared in the , NULL if none.
*
* @param is InputStream to create the reader from.
* @param guessedEnc guessed encoding
* @return the encoding declared in the
* @throws IOException thrown if there is a problem reading the stream.
*/
private static String getXmlProlog(final InputStream is, final String guessedEnc)
throws IOException {
String encoding = null;
if (guessedEnc != null) {
final byte[] bytes = new byte[BUFFER_SIZE];
is.mark(BUFFER_SIZE);
int offset = 0;
int max = BUFFER_SIZE;
int c = is.read(bytes, offset, max);
int firstGT = -1;
String xmlProlog = ""; // avoid possible NPE warning (cannot happen; this just silences the warning)
while (c != -1 && firstGT == -1 && offset < BUFFER_SIZE) {
offset += c;
max -= c;
c = is.read(bytes, offset, max);
xmlProlog = new String(bytes, 0, offset, guessedEnc);
firstGT = xmlProlog.indexOf('>');
}
if (firstGT == -1) {
if (c == -1) {
throw new IOException("Unexpected end of XML stream");
}
throw new IOException(
"XML prolog or ROOT element not found on first "
+ offset + " bytes");
}
final int bytesRead = offset;
if (bytesRead > 0) {
is.reset();
final BufferedReader bReader = new BufferedReader(new StringReader(
xmlProlog.substring(0, firstGT + 1)));
final StringBuffer prolog = new StringBuffer();
String line = bReader.readLine();
while (line != null) {
prolog.append(line);
line = bReader.readLine();
}
final Matcher m = ENCODING_PATTERN.matcher(prolog);
if (m.find()) {
encoding = m.group(1).toUpperCase(Locale.ROOT);
encoding = encoding.substring(1, encoding.length() - 1);
}
}
}
return encoding;
}
/**
* Indicates if the MIME type belongs to the APPLICATION XML family.
*
* @param mime The mime type
* @return true if the mime type belongs to the APPLICATION XML family,
* otherwise false
*/
static boolean isAppXml(final String mime) {
return mime != null &&
(mime.equals("application/xml") ||
mime.equals("application/xml-dtd") ||
mime.equals("application/xml-external-parsed-entity") ||
mime.startsWith("application/") && mime.endsWith("+xml"));
}
/**
* Indicates if the MIME type belongs to the TEXT XML family.
*
* @param mime The mime type
* @return true if the mime type belongs to the TEXT XML family,
* otherwise false
*/
static boolean isTextXml(final String mime) {
return mime != null &&
(mime.equals("text/xml") ||
mime.equals("text/xml-external-parsed-entity") ||
mime.startsWith("text/") && mime.endsWith("+xml"));
}
private static final String RAW_EX_1 =
"Invalid encoding, BOM [{0}] XML guess [{1}] XML prolog [{2}] encoding mismatch";
private static final String RAW_EX_2 =
"Invalid encoding, BOM [{0}] XML guess [{1}] XML prolog [{2}] unknown BOM";
private static final String HTTP_EX_1 =
"Invalid encoding, CT-MIME [{0}] CT-Enc [{1}] BOM [{2}] XML guess [{3}] XML prolog [{4}], BOM must be NULL";
private static final String HTTP_EX_2 =
"Invalid encoding, CT-MIME [{0}] CT-Enc [{1}] BOM [{2}] XML guess [{3}] XML prolog [{4}], encoding mismatch";
private static final String HTTP_EX_3 =
"Invalid encoding, CT-MIME [{0}] CT-Enc [{1}] BOM [{2}] XML guess [{3}] XML prolog [{4}], Invalid MIME";
}