http://codehaus-plexus.github.io/plexus-utils/: A collection of various utility classes to ease working with strings, files, command lines, XML and more. (Codehaus Plexus)
  • Jason van Zyl
  • Pete Kazmier ()
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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.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StringReader;
import java.net.URL;
import java.net.URLConnection;
import java.net.HttpURLConnection;
import java.util.Locale;
import java.util.regex.Pattern;
import java.util.regex.Matcher;
import java.text.MessageFormat;


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
/**
 * <p>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.</p>
 * 
 * <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, XmlReader handles it and things work in all parsers).</p>
 * 
 * <p>The XmlReader 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 an script
 * (following HTTP MIME and XML specifications). All this is nicely explained by Mark Pilgrim in his blog,
 * <a href="http://diveintomark.org/archives/2004/02/13/xml-media-types"> Determining the character encoding of a
 * feed</a>.</p>
 *
 * @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
 */
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.


Params:
  • encoding – charset encoding to default to.
/**
     * <p>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.</p>
     * 
     * <p>If it is set to NULL the content-type based rules are used.</p>
     * 
     * <p>By default it is NULL.</p>
     *
     * @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.


Returns:the default encoding to use.
/**
     * <p>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.</p>
     * 
     * <p>If it is NULL the content-type based rules are used.</p>
     *
     * @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.



Params:
  • file – File to create a Reader from.
Throws:
  • IOException – thrown if there is a problem reading the file.
/**
     * Creates 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>
     * 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 IOException thrown if there is a problem reading the file.
     */
    public XmlReader( 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.



Params:
  • is – InputStream to create a Reader from.
Throws:
  • IOException – thrown if there is a problem reading the stream.
/**
     * Creates a Reader for a raw InputStream.
     * <p>
     * It follows the same logic used for files.
     * <p>
     * It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
     * <p>
     *
     * @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.



Params:
  • is – InputStream to create a Reader from.
  • lenient – indicates if the charset encoding detection should be relaxed.
Throws:
/**
     * Creates a Reader for a raw InputStream.
     * <p>
     * It follows the same logic used for files.
     * <p>
     * If lenient detection is indicated and the detection above fails as per specifications it then attempts the
     * following:
     * <p>
     * If the content type was 'text/html' it replaces it with 'text/xml' and tries the detection again.
     * <p>
     * Else if the XML prolog had a charset encoding that encoding is used.
     * <p>
     * Else if the content type had a charset encoding that encoding is used.
     * <p>
     * Else 'UTF-8' is used.
     * <p>
     * If lenient detection is indicated an XmlStreamReaderException is never thrown.
     * <p>
     *
     * @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.



Params:
  • url – URL to create a Reader from.
Throws:
  • IOException – thrown if there is a problem reading the stream of the URL.
/**
     * Creates 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>
     * 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>
     * 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 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.



Params:
  • conn – URLConnection to create a Reader from.
Throws:
  • IOException – thrown if there is a problem reading the stream of the URLConnection.
/**
     * Creates 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>
     * 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>
     * It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
     * <p>
     *
     * @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.



Params:
  • is – InputStream to create the reader from.
  • httpContentType – content-type header to use for the resolution of the charset encoding.
Throws:
  • IOException – thrown if there is a problem reading the file.
/**
     * Creates a Reader using an InputStream an 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>
     * It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
     * <p>
     *
     * @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.



Params:
  • is – InputStream to create the reader from.
  • httpContentType – content-type header to use for the resolution of the charset encoding.
  • lenient – indicates if the charset encoding detection should be relaxed.
Throws:
/**
     * Creates a Reader using an InputStream an 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>
     * If lenient detection is indicated and the detection above fails as per specifications it then attempts the
     * following:
     * <p>
     * If the content type was 'text/html' it replaces it with 'text/xml' and tries the detection again.
     * <p>
     * Else if the XML prolog had a charset encoding that encoding is used.
     * <p>
     * Else if the content type had a charset encoding that encoding is used.
     * <p>
     * Else 'UTF-8' is used.
     * <p>
     * If lenient detection is indicated an XmlStreamReaderException is never thrown.
     * <p>
     *
     * @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, 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.



Params:
  • is – InputStream to create the reader from.
  • httpContentType – content-type header to use for the resolution of the charset encoding.
  • lenient – indicates if the charset encoding detection should be relaxed.
Throws:
/**
     * Creates a Reader using an InputStream an 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>
     * If lenient detection is indicated and the detection above fails as per specifications it then attempts the
     * following:
     * <p>
     * If the content type was 'text/html' it replaces it with 'text/xml' and tries the detection again.
     * <p>
     * Else if the XML prolog had a charset encoding that encoding is used.
     * <p>
     * Else if the content type had a charset encoding that encoding is used.
     * <p>
     * Else 'UTF-8' is used.
     * <p>
     * If lenient detection is indicated an XmlStreamReaderException is never thrown.
     * <p>
     *
     * @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.



Returns:charset encoding.
/**
     * Returns the charset encoding of the XmlReader.
     * <p>
     *
     * @return charset encoding.
     */
    public String getEncoding()
    {
        return _encoding;
    }

    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.
/**
     * Closes the XmlReader stream.
     * <p>
     *
     * @throws IOException thrown if there was a problem closing the stream.
     */
    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, '<?'
    private static String getXMLGuessEncoding( BufferedInputStream is )
        throws IOException
    {
        String encoding = null;
        int[] bytes = new int[4];
        is.mark( 4 );
        bytes[0] = is.read();
        bytes[1] = is.read();
        bytes[2] = is.read();
        bytes[3] = is.read();
        is.reset();

        if ( bytes[0] == 0x00 && bytes[1] == 0x3C && bytes[2] == 0x00 && bytes[3] == 0x3F )
        {
            encoding = UTF_16BE;
        }
        else if ( bytes[0] == 0x3C && bytes[1] == 0x00 && bytes[2] == 0x3F && bytes[3] == 0x00 )
        {
            encoding = UTF_16LE;
        }
        else if ( bytes[0] == 0x3C && bytes[1] == 0x3F && bytes[2] == 0x78 && bytes[3] == 0x6D )
        {
            encoding = UTF_8;
        }
        else if ( bytes[0] == 0x4C && bytes[1] == 0x6F && bytes[2] == 0xA7 && bytes[3] == 0x94 )
        {
            encoding = EBCDIC;
        }
        return encoding;
    }

    static final Pattern ENCODING_PATTERN =
        Pattern.compile( "<\\?xml.*encoding[\\s]*=[\\s]*((?:\".[^\"]*\")|(?:'.[^']*'))", Pattern.MULTILINE );

    // returns the encoding declared in the <?xml encoding=...?>, 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" );

}