XmlStreamReader.java
/*
* 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.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.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.text.MessageFormat;
import java.util.Locale;
import java.util.Objects;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.commons.io.ByteOrderMark;
import org.apache.commons.io.Charsets;
import org.apache.commons.io.IOUtils;
import org.apache.commons.io.build.AbstractStreamBuilder;
import org.apache.commons.io.function.IOConsumer;
import org.apache.commons.io.output.XmlStreamWriter;
/**
* Character stream that handles all the necessary Voodoo to figure out the charset encoding of the XML document within the stream.
* <p>
* IMPORTANT: This class is not related in any way to the org.xml.sax.XMLReader. This one IS a character stream.
* </p>
* <p>
* 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).
* </p>
* <p>
* The XmlStreamReader class handles the charset encoding of XML documents in Files, raw streams and HTTP streams by offering a wide set of constructors.
* </p>
* <p>
* 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, <a href="https://diveintomark.org/archives/2004/02/13/xml-media-types">
* Determining the character encoding of a feed</a>.
* </p>
* <p>
* To build an instance, use {@link Builder}.
* </p>
* <p>
* Originally developed for <a href="https://rome.dev.java.net">ROME</a> under Apache License 2.0.
* </p>
*
* @see Builder
* @see org.apache.commons.io.output.XmlStreamWriter
* @since 2.0
*/
public class XmlStreamReader extends Reader {
// @formatter:off
/**
* Builds a new {@link XmlStreamWriter}.
*
* Constructs a Reader using an InputStream and the associated content-type header. This constructor is lenient regarding the encoding detection.
* <p>
* 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.
* </p>
* <p>
* If lenient detection is indicated and the detection above fails as per specifications it then attempts the following:
* </p>
* <p>
* If the content type was 'text/html' it replaces it with 'text/xml' and tries the detection again.
* </p>
* <p>
* Else if the XML prolog had a charset encoding that encoding is used.
* </p>
* <p>
* Else if the content type had a charset encoding that encoding is used.
* </p>
* <p>
* Else 'UTF-8' is used.
* </p>
* <p>
* If lenient detection is indicated an XmlStreamReaderException is never thrown.
* </p>
* <p>
* For example:
* </p>
*
* <pre>{@code
* XmlStreamReader r = XmlStreamReader.builder()
* .setPath(path)
* .setCharset(StandardCharsets.UTF_8)
* .get();
* }
* </pre>
*
* @see #get()
* @since 2.12.0
*/
// @formatter:on
public static class Builder extends AbstractStreamBuilder<XmlStreamReader, Builder> {
private boolean nullCharset = true;
private boolean lenient = true;
private String httpContentType;
/**
* Builds a new {@link XmlStreamWriter}.
* <p>
* You must set input that supports {@link #getInputStream()}, otherwise, this method throws an exception.
* </p>
* <p>
* This builder use the following aspects:
* </p>
* <ul>
* <li>{@link #getInputStream()}</li>
* <li>{@link #getCharset()}</li>
* <li>lenient</li>
* <li>httpContentType</li>
* </ul>
*
* @return a new instance.
* @throws IllegalStateException if the {@code origin} is {@code null}.
* @throws UnsupportedOperationException if the origin cannot be converted to an {@link InputStream}.
* @throws IOException if an I/O error occurs.
* @throws XmlStreamReaderException thrown if the Charset encoding could not be determined according to the specification.
* @see #getInputStream()
*/
@SuppressWarnings("resource")
@Override
public XmlStreamReader get() throws IOException {
final String defaultEncoding = nullCharset ? null : getCharset().name();
// @formatter:off
return httpContentType == null
? new XmlStreamReader(getInputStream(), lenient, defaultEncoding)
: new XmlStreamReader(getInputStream(), httpContentType, lenient, defaultEncoding);
// @formatter:on
}
@Override
public Builder setCharset(final Charset charset) {
nullCharset = charset == null;
return super.setCharset(charset);
}
@Override
public Builder setCharset(final String charset) {
nullCharset = charset == null;
return super.setCharset(Charsets.toCharset(charset, getCharsetDefault()));
}
/**
* Sets the HTTP content type.
*
* @param httpContentType the HTTP content type.
* @return {@code this} instance.
*/
public Builder setHttpContentType(final String httpContentType) {
this.httpContentType = httpContentType;
return this;
}
/**
* Sets the lenient toggle.
*
* @param lenient the lenient toggle.
* @return {@code this} instance.
*/
public Builder setLenient(final boolean lenient) {
this.lenient = lenient;
return this;
}
}
private static final String UTF_8 = StandardCharsets.UTF_8.name();
private static final String US_ASCII = StandardCharsets.US_ASCII.name();
private static final String UTF_16BE = StandardCharsets.UTF_16BE.name();
private static final String UTF_16LE = StandardCharsets.UTF_16LE.name();
private static final String UTF_32BE = "UTF-32BE";
private static final String UTF_32LE = "UTF-32LE";
private static final String UTF_16 = StandardCharsets.UTF_16.name();
private static final String UTF_32 = "UTF-32";
private static final String EBCDIC = "CP1047";
private static final ByteOrderMark[] BOMS = { 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(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 static final Pattern CHARSET_PATTERN = Pattern.compile("charset=[\"']?([.[^; \"']]*)[\"']?");
/**
* Pattern capturing the encoding of the <a href="https://www.w3.org/TR/REC-xml/#sec-pi">{@code 'xml'} processing instruction</a>.
* <p>
* See also the <a href="https://www.w3.org/TR/2008/REC-xml-20081126/#NT-EncName">NT-EncName</a> XML specification.
* </p>
* <p>
* Note the documented pattern is:
* </p>
* <pre>
* EncName ::= [A-Za-z] ([A-Za-z0-9._] | '-')*
* </pre>
* <p>
* However this does not match all the aliases that are supported by Java. For example, {@code '437'}, {@code 'ISO_8859-1:1987'} and
* {@code 'ebcdic-de-273+euro'}.
* </p>
*/
public static final Pattern ENCODING_PATTERN = Pattern.compile(
// @formatter:off
"^<\\?xml\\s+"
+ "(?:version\\s*=\\s*(?:(?:\"1\\.[0-9]+\")|(?:'1.[0-9]+'))\\s+)??"
+ "encoding\\s*=\\s*"
+ "((?:\"[A-Za-z0-9][A-Za-z0-9._+:-]*\")" // double-quoted
+ "|(?:'[A-Za-z0-9][A-Za-z0-9._+:-]*'))", // single-quoted
Pattern.MULTILINE);
// @formatter:on
private static final String RAW_EX_1 = "Illegal encoding, BOM [{0}] XML guess [{1}] XML prolog [{2}] encoding mismatch";
private static final String RAW_EX_2 = "Illegal encoding, BOM [{0}] XML guess [{1}] XML prolog [{2}] unknown BOM";
private static final String HTTP_EX_1 = "Illegal 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 = "Illegal encoding, CT-MIME [{0}] CT-Enc [{1}] BOM [{2}] XML guess [{3}] XML prolog [{4}], encoding mismatch";
private static final String HTTP_EX_3 = "Illegal encoding, CT-MIME [{0}] CT-Enc [{1}] BOM [{2}] XML guess [{3}] XML prolog [{4}], Illegal MIME";
/**
* Constructs a new {@link Builder}.
*
* @return a new {@link Builder}.
* @since 2.12.0
*/
public static Builder builder() {
return new Builder();
}
/**
* Gets the charset parameter value, {@code null} if not present, {@code null} if httpContentType is {@code 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;
}
/**
* Gets the MIME type or {@code null} if httpContentType is {@code 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(";");
mime = i >= 0 ? httpContentType.substring(0, i) : httpContentType;
mime = mime.trim();
}
return mime;
}
/**
* Gets the encoding declared in the <?xml encoding=...?>, {@code null} if none.
*
* @param inputStream InputStream to create the reader from.
* @param guessedEnc guessed encoding
* @return the encoding declared in the <?xml encoding=...?>
* @throws IOException thrown if there is a problem reading the stream.
*/
private static String getXmlProlog(final InputStream inputStream, final String guessedEnc) throws IOException {
String encoding = null;
if (guessedEnc != null) {
final byte[] bytes = IOUtils.byteArray();
inputStream.mark(IOUtils.DEFAULT_BUFFER_SIZE);
int offset = 0;
int max = IOUtils.DEFAULT_BUFFER_SIZE;
int c = inputStream.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 < IOUtils.DEFAULT_BUFFER_SIZE) {
offset += c;
max -= c;
c = inputStream.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) {
inputStream.reset();
final BufferedReader bReader = new BufferedReader(new StringReader(xmlProlog.substring(0, firstGT + 1)));
final StringBuilder prolog = new StringBuilder();
IOConsumer.forEach(bReader.lines(), l -> prolog.append(l).append(' '));
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;
}
/**
* Tests 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"));
}
/**
* Tests 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 final Reader reader;
private final String encoding;
private final String defaultEncoding;
/**
* Constructs a Reader for a File.
* <p>
* It looks for the UTF-8 BOM first, if none sniffs the XML prolog charset, if this is also missing defaults to UTF-8.
* </p>
* <p>
* It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
* </p>
*
* @param file File to create a Reader from.
* @throws NullPointerException if the input is {@code null}.
* @throws IOException thrown if there is a problem reading the file.
* @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
*/
@Deprecated
public XmlStreamReader(final File file) throws IOException {
this(Objects.requireNonNull(file, "file").toPath());
}
/**
* Constructs a Reader for a raw InputStream.
* <p>
* It follows the same logic used for files.
* </p>
* <p>
* It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
* </p>
*
* @param inputStream InputStream to create a Reader from.
* @throws NullPointerException if the input stream is {@code null}.
* @throws IOException thrown if there is a problem reading the stream.
* @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
*/
@Deprecated
public XmlStreamReader(final InputStream inputStream) throws IOException {
this(inputStream, true);
}
/**
* Constructs a Reader for a raw InputStream.
* <p>
* It follows the same logic used for files.
* </p>
* <p>
* If lenient detection is indicated and the detection above fails as per specifications it then attempts the following:
* </p>
* <p>
* If the content type was 'text/html' it replaces it with 'text/xml' and tries the detection again.
* </p>
* <p>
* Else if the XML prolog had a charset encoding that encoding is used.
* </p>
* <p>
* Else if the content type had a charset encoding that encoding is used.
* </p>
* <p>
* Else 'UTF-8' is used.
* </p>
* <p>
* If lenient detection is indicated an XmlStreamReaderException is never thrown.
* </p>
*
* @param inputStream InputStream to create a Reader from.
* @param lenient indicates if the charset encoding detection should be relaxed.
* @throws NullPointerException if the input stream is {@code null}.
* @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 specification.
* @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
*/
@Deprecated
public XmlStreamReader(final InputStream inputStream, final boolean lenient) throws IOException {
this(inputStream, lenient, null);
}
/**
* Constructs a Reader for a raw InputStream.
* <p>
* It follows the same logic used for files.
* </p>
* <p>
* If lenient detection is indicated and the detection above fails as per specifications it then attempts the following:
* </p>
* <p>
* If the content type was 'text/html' it replaces it with 'text/xml' and tries the detection again.
* </p>
* <p>
* Else if the XML prolog had a charset encoding that encoding is used.
* </p>
* <p>
* Else if the content type had a charset encoding that encoding is used.
* </p>
* <p>
* Else 'UTF-8' is used.
* </p>
* <p>
* If lenient detection is indicated an XmlStreamReaderException is never thrown.
* </p>
*
* @param inputStream InputStream to create a Reader from.
* @param lenient indicates if the charset encoding detection should be relaxed.
* @param defaultEncoding The default encoding
* @throws NullPointerException if the input stream is {@code null}.
* @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 specification.
* @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
*/
@Deprecated
@SuppressWarnings("resource") // InputStream is managed through a InputStreamReader in this instance.
public XmlStreamReader(final InputStream inputStream, final boolean lenient, final String defaultEncoding) throws IOException {
this.defaultEncoding = defaultEncoding;
final BOMInputStream bom = new BOMInputStream(new BufferedInputStream(Objects.requireNonNull(inputStream, "inputStream"), IOUtils.DEFAULT_BUFFER_SIZE),
false, BOMS);
final BOMInputStream pis = new BOMInputStream(bom, true, XML_GUESS_BYTES);
this.encoding = processHttpStream(bom, pis, lenient);
this.reader = new InputStreamReader(pis, encoding);
}
/**
* Constructs a Reader using an InputStream and the associated content-type header.
* <p>
* 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.
* </p>
* <p>
* It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
* </p>
*
* @param inputStream InputStream to create the reader from.
* @param httpContentType content-type header to use for the resolution of the charset encoding.
* @throws NullPointerException if the input stream is {@code null}.
* @throws IOException thrown if there is a problem reading the file.
* @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
*/
@Deprecated
public XmlStreamReader(final InputStream inputStream, final String httpContentType) throws IOException {
this(inputStream, httpContentType, true);
}
/**
* Constructs a Reader using an InputStream and the associated content-type header. This constructor is lenient regarding the encoding detection.
* <p>
* 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.
* </p>
* <p>
* If lenient detection is indicated and the detection above fails as per specifications it then attempts the following:
* </p>
* <p>
* If the content type was 'text/html' it replaces it with 'text/xml' and tries the detection again.
* </p>
* <p>
* Else if the XML prolog had a charset encoding that encoding is used.
* </p>
* <p>
* Else if the content type had a charset encoding that encoding is used.
* </p>
* <p>
* Else 'UTF-8' is used.
* </p>
* <p>
* If lenient detection is indicated an XmlStreamReaderException is never thrown.
* </p>
*
* @param inputStream 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 NullPointerException if the input stream is {@code null}.
* @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 specification.
* @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
*/
@Deprecated
public XmlStreamReader(final InputStream inputStream, final String httpContentType, final boolean lenient) throws IOException {
this(inputStream, httpContentType, lenient, null);
}
/**
* Constructs a Reader using an InputStream and the associated content-type header. This constructor is lenient regarding the encoding detection.
* <p>
* 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.
* </p>
* <p>
* If lenient detection is indicated and the detection above fails as per specifications it then attempts the following:
* </p>
* <p>
* If the content type was 'text/html' it replaces it with 'text/xml' and tries the detection again.
* </p>
* <p>
* Else if the XML prolog had a charset encoding that encoding is used.
* </p>
* <p>
* Else if the content type had a charset encoding that encoding is used.
* </p>
* <p>
* Else 'UTF-8' is used.
* </p>
* <p>
* If lenient detection is indicated an XmlStreamReaderException is never thrown.
* </p>
*
* @param inputStream 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 NullPointerException if the input stream is {@code null}.
* @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 specification.
* @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
*/
@Deprecated
@SuppressWarnings("resource") // InputStream is managed through a InputStreamReader in this instance.
public XmlStreamReader(final InputStream inputStream, final String httpContentType, final boolean lenient, final String defaultEncoding)
throws IOException {
this.defaultEncoding = defaultEncoding;
final BOMInputStream bom = new BOMInputStream(new BufferedInputStream(Objects.requireNonNull(inputStream, "inputStream"), IOUtils.DEFAULT_BUFFER_SIZE),
false, BOMS);
final BOMInputStream pis = new BOMInputStream(bom, true, XML_GUESS_BYTES);
this.encoding = processHttpStream(bom, pis, lenient, httpContentType);
this.reader = new InputStreamReader(pis, encoding);
}
/**
* Constructs a Reader for a File.
* <p>
* It looks for the UTF-8 BOM first, if none sniffs the XML prolog charset, if this is also missing defaults to UTF-8.
* </p>
* <p>
* It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
* </p>
*
* @param file File to create a Reader from.
* @throws NullPointerException if the input is {@code null}.
* @throws IOException thrown if there is a problem reading the file.
* @since 2.11.0
* @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
*/
@Deprecated
@SuppressWarnings("resource") // InputStream is managed through another reader in this instance.
public XmlStreamReader(final Path file) throws IOException {
this(Files.newInputStream(Objects.requireNonNull(file, "file")));
}
/**
* Constructs a Reader using the InputStream of a URL.
* <p>
* 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.
* </p>
* <p>
* 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.
* </p>
* <p>
* It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
* </p>
*
* @param url URL to create a Reader from.
* @throws NullPointerException if the input is {@code null}.
* @throws IOException thrown if there is a problem reading the stream of the URL.
*/
public XmlStreamReader(final URL url) throws IOException {
this(Objects.requireNonNull(url, "url").openConnection(), null);
}
/**
* Constructs a Reader using the InputStream of a URLConnection.
* <p>
* 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.
* </p>
* <p>
* 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.
* </p>
* <p>
* It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
* </p>
*
* @param urlConnection URLConnection to create a Reader from.
* @param defaultEncoding The default encoding
* @throws NullPointerException if the input is {@code null}.
* @throws IOException thrown if there is a problem reading the stream of the URLConnection.
*/
public XmlStreamReader(final URLConnection urlConnection, final String defaultEncoding) throws IOException {
Objects.requireNonNull(urlConnection, "urlConnection");
this.defaultEncoding = defaultEncoding;
final boolean lenient = true;
final String contentType = urlConnection.getContentType();
final InputStream inputStream = urlConnection.getInputStream();
@SuppressWarnings("resource") // managed by the InputStreamReader tracked by this instance
// @formatter:off
final BOMInputStream bomInput = BOMInputStream.builder()
.setInputStream(new BufferedInputStream(inputStream, IOUtils.DEFAULT_BUFFER_SIZE))
.setInclude(false)
.setByteOrderMarks(BOMS)
.get();
@SuppressWarnings("resource")
final BOMInputStream piInput = BOMInputStream.builder()
.setInputStream(new BufferedInputStream(bomInput, IOUtils.DEFAULT_BUFFER_SIZE))
.setInclude(true)
.setByteOrderMarks(XML_GUESS_BYTES)
.get();
// @formatter:on
if (urlConnection instanceof HttpURLConnection || contentType != null) {
this.encoding = processHttpStream(bomInput, piInput, lenient, contentType);
} else {
this.encoding = processHttpStream(bomInput, piInput, lenient);
}
this.reader = new InputStreamReader(piInput, encoding);
}
/**
* Calculates the HTTP encoding.
* @param bomEnc BOM encoding
* @param xmlGuessEnc XML Guess encoding
* @param xmlEnc XML encoding
* @param lenient indicates if the charset encoding detection should be relaxed.
* @param httpContentType The HTTP content type
*
* @return the HTTP encoding
* @throws IOException thrown if there is a problem reading the stream.
*/
String calculateHttpEncoding(final String bomEnc, final String xmlGuessEnc, final String xmlEnc, final boolean lenient, final String httpContentType)
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;
}
/**
* 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);
}
/**
* Closes the XmlStreamReader stream.
*
* @throws IOException thrown if there was a problem closing the stream.
*/
@Override
public void close() throws IOException {
reader.close();
}
/**
* Does 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(ex.getBomEncoding(), ex.getXmlGuessEncoding(), ex.getXmlEncoding(), true, httpContentType);
} 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;
}
/**
* Gets 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.
* <p>
* If it is {@code null} the content-type based rules are used.
* </p>
*
* @return the default encoding to use.
*/
public String getDefaultEncoding() {
return defaultEncoding;
}
/**
* Gets the charset encoding of the XmlStreamReader.
*
* @return charset encoding.
*/
public String getEncoding() {
return encoding;
}
/**
* Process the raw stream.
*
* @param bomInput BOMInputStream to detect byte order marks
* @param piInput 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 processHttpStream(final BOMInputStream bomInput, final BOMInputStream piInput, final boolean lenient) throws IOException {
final String bomEnc = bomInput.getBOMCharsetName();
final String xmlGuessEnc = piInput.getBOMCharsetName();
final String xmlEnc = getXmlProlog(piInput, xmlGuessEnc);
try {
return calculateRawEncoding(bomEnc, xmlGuessEnc, xmlEnc);
} catch (final XmlStreamReaderException ex) {
if (lenient) {
return doLenientDetection(null, ex);
}
throw ex;
}
}
/**
* Processes an HTTP stream.
*
* @param bomInput BOMInputStream to detect byte order marks
* @param piInput BOMInputStream to guess XML encoding
* @param lenient indicates if the charset encoding detection should be relaxed.
* @param httpContentType The HTTP content type
* @return the encoding to be used
* @throws IOException thrown if there is a problem reading the stream.
*/
private String processHttpStream(final BOMInputStream bomInput, final BOMInputStream piInput, final boolean lenient, final String httpContentType)
throws IOException {
final String bomEnc = bomInput.getBOMCharsetName();
final String xmlGuessEnc = piInput.getBOMCharsetName();
final String xmlEnc = getXmlProlog(piInput, xmlGuessEnc);
try {
return calculateHttpEncoding(bomEnc, xmlGuessEnc, xmlEnc, lenient, httpContentType);
} catch (final XmlStreamReaderException ex) {
if (lenient) {
return doLenientDetection(httpContentType, ex);
}
throw ex;
}
}
/**
* Reads the underlying reader's {@code 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);
}
}