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/*
 * Copyright 2004 Sun Microsystems, Inc.
 *
 * Licensed 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.codehaus.plexus.util.xml;

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.file.Files;
import java.text.MessageFormat;
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * 

Character stream that handles (or at least attempts to) all the necessary Voodo 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, XmlReader handles it and things work in all parsers).

* *

The XmlReader 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 an 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.

* * @author Alejandro Abdelnur * @version revision 1.17 taken on 26/06/2007 from Rome (see * https://rome.dev.java.net/source/browse/rome/src/java/com/sun/syndication/io/XmlReader.java) * @deprecated use XmlStreamReader * @since 1.4.3 */ @Deprecated public class XmlReader 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_16 = "UTF-16"; private static final String EBCDIC = "CP1047"; private static String _staticDefaultEncoding = null; private Reader _reader; private String _encoding; private String _defaultEncoding; /** *

Sets 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 set to NULL the content-type based rules are used.

* *

By default it is NULL.

* * @param encoding charset encoding to default to. */ public static void setDefaultEncoding(String encoding) { _staticDefaultEncoding = encoding; } /** *

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 static String getDefaultEncoding() { return _staticDefaultEncoding; } /** * 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 XmlReader(File file) throws IOException { this(Files.newInputStream(file.toPath())); } /** * 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 XmlReader(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 XmlReader(InputStream is, boolean lenient) throws IOException, XmlStreamReaderException { _defaultEncoding = _staticDefaultEncoding; try { doRawStream(is, lenient); } catch (XmlStreamReaderException ex) { if (!lenient) { throw ex; } else { doLenientDetection(null, ex); } } } /** * 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 XmlReader(URL url) throws IOException { this(url.openConnection()); } /** * 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. * @throws IOException thrown if there is a problem reading the stream of the URLConnection. */ public XmlReader(URLConnection conn) throws IOException { _defaultEncoding = _staticDefaultEncoding; boolean lenient = true; if (conn instanceof HttpURLConnection) { try { doHttpStream(conn.getInputStream(), conn.getContentType(), lenient); } catch (XmlStreamReaderException ex) { doLenientDetection(conn.getContentType(), ex); } } else if (conn.getContentType() != null) { try { doHttpStream(conn.getInputStream(), conn.getContentType(), lenient); } catch (XmlStreamReaderException ex) { doLenientDetection(conn.getContentType(), ex); } } else { try { doRawStream(conn.getInputStream(), lenient); } catch (XmlStreamReaderException ex) { doLenientDetection(null, ex); } } } /** * Creates a Reader using an InputStream an 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 XmlReader(InputStream is, String httpContentType) throws IOException { this(is, httpContentType, true); } /** * Creates a Reader using an InputStream an 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 encoding to use * @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 XmlReader(InputStream is, String httpContentType, boolean lenient, String defaultEncoding) throws IOException, XmlStreamReaderException { _defaultEncoding = (defaultEncoding == null) ? _staticDefaultEncoding : defaultEncoding; try { doHttpStream(is, httpContentType, lenient); } catch (XmlStreamReaderException ex) { if (!lenient) { throw ex; } else { doLenientDetection(httpContentType, ex); } } } /** * Creates a Reader using an InputStream an 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 XmlReader(InputStream is, String httpContentType, boolean lenient) throws IOException, XmlStreamReaderException { this(is, httpContentType, lenient, null); } private void doLenientDetection(String httpContentType, XmlStreamReaderException ex) throws IOException { if (httpContentType != null) { if (httpContentType.startsWith("text/html")) { httpContentType = httpContentType.substring("text/html".length()); httpContentType = "text/xml" + httpContentType; try { doHttpStream(ex.getInputStream(), httpContentType, true); ex = null; } catch (XmlStreamReaderException ex2) { ex = ex2; } } } if (ex != null) { String encoding = ex.getXmlEncoding(); if (encoding == null) { encoding = ex.getContentTypeEncoding(); } if (encoding == null) { encoding = (_defaultEncoding == null) ? UTF_8 : _defaultEncoding; } prepareReader(ex.getInputStream(), encoding); } } /** * Returns the charset encoding of the XmlReader. *

* * @return charset encoding. */ public String getEncoding() { return _encoding; } @Override public int read(char[] buf, int offset, int len) throws IOException { return _reader.read(buf, offset, len); } /** * Closes the XmlReader stream. *

* * @throws IOException thrown if there was a problem closing the stream. */ @Override public void close() throws IOException { _reader.close(); } private void doRawStream(InputStream is, boolean lenient) throws IOException { BufferedInputStream pis = new BufferedInputStream(is, BUFFER_SIZE); String bomEnc = getBOMEncoding(pis); String xmlGuessEnc = getXMLGuessEncoding(pis); String xmlEnc = getXmlProlog(pis, xmlGuessEnc); String encoding = calculateRawEncoding(bomEnc, xmlGuessEnc, xmlEnc, pis); prepareReader(pis, encoding); } private void doHttpStream(InputStream is, String httpContentType, boolean lenient) throws IOException { BufferedInputStream pis = new BufferedInputStream(is, BUFFER_SIZE); String cTMime = getContentTypeMime(httpContentType); String cTEnc = getContentTypeEncoding(httpContentType); String bomEnc = getBOMEncoding(pis); String xmlGuessEnc = getXMLGuessEncoding(pis); String xmlEnc = getXmlProlog(pis, xmlGuessEnc); String encoding = calculateHttpEncoding(cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc, pis, lenient); prepareReader(pis, encoding); } private void prepareReader(InputStream is, String encoding) throws IOException { _reader = new InputStreamReader(is, encoding); _encoding = encoding; } // InputStream is passed for XmlStreamReaderException creation only private String calculateRawEncoding(String bomEnc, String xmlGuessEnc, String xmlEnc, InputStream is) throws IOException { String encoding; if (bomEnc == null) { if (xmlGuessEnc == null || xmlEnc == null) { encoding = (_defaultEncoding == null) ? UTF_8 : _defaultEncoding; } else if (xmlEnc.equals(UTF_16) && (xmlGuessEnc.equals(UTF_16BE) || xmlGuessEnc.equals(UTF_16LE))) { encoding = xmlGuessEnc; } else { encoding = xmlEnc; } } else if (bomEnc.equals(UTF_8)) { if (xmlGuessEnc != null && !xmlGuessEnc.equals(UTF_8)) { throw new XmlStreamReaderException( RAW_EX_1.format(new Object[] {bomEnc, xmlGuessEnc, xmlEnc}), bomEnc, xmlGuessEnc, xmlEnc, is); } if (xmlEnc != null && !xmlEnc.equals(UTF_8)) { throw new XmlStreamReaderException( RAW_EX_1.format(new Object[] {bomEnc, xmlGuessEnc, xmlEnc}), bomEnc, xmlGuessEnc, xmlEnc, is); } encoding = UTF_8; } else if (bomEnc.equals(UTF_16BE) || bomEnc.equals(UTF_16LE)) { if (xmlGuessEnc != null && !xmlGuessEnc.equals(bomEnc)) { throw new IOException(RAW_EX_1.format(new Object[] {bomEnc, xmlGuessEnc, xmlEnc})); } if (xmlEnc != null && !xmlEnc.equals(UTF_16) && !xmlEnc.equals(bomEnc)) { throw new XmlStreamReaderException( RAW_EX_1.format(new Object[] {bomEnc, xmlGuessEnc, xmlEnc}), bomEnc, xmlGuessEnc, xmlEnc, is); } encoding = bomEnc; } else { throw new XmlStreamReaderException( RAW_EX_2.format(new Object[] {bomEnc, xmlGuessEnc, xmlEnc}), bomEnc, xmlGuessEnc, xmlEnc, is); } return encoding; } // InputStream is passed for XmlStreamReaderException creation only private String calculateHttpEncoding( String cTMime, String cTEnc, String bomEnc, String xmlGuessEnc, String xmlEnc, InputStream is, boolean lenient) throws IOException { String encoding; if (lenient & xmlEnc != null) { encoding = xmlEnc; } else { boolean appXml = isAppXml(cTMime); boolean textXml = isTextXml(cTMime); if (appXml || textXml) { if (cTEnc == null) { if (appXml) { encoding = calculateRawEncoding(bomEnc, xmlGuessEnc, xmlEnc, is); } else { encoding = (_defaultEncoding == null) ? US_ASCII : _defaultEncoding; } } else if (bomEnc != null && (cTEnc.equals(UTF_16BE) || cTEnc.equals(UTF_16LE))) { throw new XmlStreamReaderException( HTTP_EX_1.format(new Object[] {cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc}), cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc, is); } else if (cTEnc.equals(UTF_16)) { if (bomEnc != null && bomEnc.startsWith(UTF_16)) { encoding = bomEnc; } else { throw new XmlStreamReaderException( HTTP_EX_2.format(new Object[] {cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc}), cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc, is); } } else { encoding = cTEnc; } } else { throw new XmlStreamReaderException( HTTP_EX_3.format(new Object[] {cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc}), cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc, is); } } return encoding; } // returns MIME type or NULL if httpContentType is NULL private static String getContentTypeMime(String httpContentType) { String mime = null; if (httpContentType != null) { int i = httpContentType.indexOf(";"); mime = ((i == -1) ? httpContentType : httpContentType.substring(0, i)).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 private static String getContentTypeEncoding(String httpContentType) { String encoding = null; if (httpContentType != null) { int i = httpContentType.indexOf(";"); if (i > -1) { String postMime = httpContentType.substring(i + 1); Matcher m = CHARSET_PATTERN.matcher(postMime); encoding = (m.find()) ? m.group(1) : null; encoding = (encoding != null) ? encoding.toUpperCase(Locale.ENGLISH) : null; } } return encoding; } // returns the BOM in the stream, NULL if not present, // if there was BOM the in the stream it is consumed private static String getBOMEncoding(BufferedInputStream is) throws IOException { String encoding = null; int[] bytes = new int[3]; is.mark(3); bytes[0] = is.read(); bytes[1] = is.read(); bytes[2] = is.read(); if (bytes[0] == 0xFE && bytes[1] == 0xFF) { encoding = UTF_16BE; is.reset(); is.read(); is.read(); } else if (bytes[0] == 0xFF && bytes[1] == 0xFE) { encoding = UTF_16LE; is.reset(); is.read(); is.read(); } else if (bytes[0] == 0xEF && bytes[1] == 0xBB && bytes[2] == 0xBF) { encoding = UTF_8; } else { is.reset(); } return encoding; } // returns the best guess for the encoding by looking the first bytes of the stream, ', NULL if none private static String getXmlProlog(BufferedInputStream is, String guessedEnc) throws IOException { String encoding = null; if (guessedEnc != null) { 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 = null; 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"); } else { throw new IOException("XML prolog or ROOT element not found on first " + offset + " bytes"); } } int bytesRead = offset; if (bytesRead > 0) { is.reset(); BufferedReader bReader = new BufferedReader(new StringReader(xmlProlog.substring(0, firstGT + 1))); StringBuilder prolog = new StringBuilder(); String line = bReader.readLine(); while (line != null) { prolog.append(line); line = bReader.readLine(); } Matcher m = ENCODING_PATTERN.matcher(prolog); if (m.find()) { encoding = m.group(1).toUpperCase(Locale.ENGLISH); encoding = encoding.substring(1, encoding.length() - 1); } } } return encoding; } // indicates if the MIME type belongs to the APPLICATION XML family private static boolean isAppXml(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 private static boolean isTextXml(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 MessageFormat RAW_EX_1 = new MessageFormat("Invalid encoding, BOM [{0}] XML guess [{1}] XML prolog [{2}] encoding mismatch"); private static final MessageFormat RAW_EX_2 = new MessageFormat("Invalid encoding, BOM [{0}] XML guess [{1}] XML prolog [{2}] unknown BOM"); private static final MessageFormat HTTP_EX_1 = new MessageFormat( "Invalid encoding, CT-MIME [{0}] CT-Enc [{1}] BOM [{2}] XML guess [{3}] XML prolog [{4}], BOM must be NULL"); private static final MessageFormat HTTP_EX_2 = new MessageFormat( "Invalid encoding, CT-MIME [{0}] CT-Enc [{1}] BOM [{2}] XML guess [{3}] XML prolog [{4}], encoding mismatch"); private static final MessageFormat HTTP_EX_3 = new MessageFormat( "Invalid encoding, CT-MIME [{0}] CT-Enc [{1}] BOM [{2}] XML guess [{3}] XML prolog [{4}], Invalid MIME"); }





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