http://commons.apache.org/proper/commons-io/: The Apache Commons IO library contains utility classes, stream implementations, file filters, file comparators, endian transformation classes, and much more. (The Apache Software Foundation)
  • Rahul Akolkar
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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.io.input;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StringReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.text.MessageFormat;
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.io.ByteOrderMark;


Character stream that handles all the necessary Voodoo to figure out the
charset encoding of the XML document within the stream.


IMPORTANT: This class is not related in any way to the org.xml.sax.XMLReader.
This one IS a character stream.


All this has to be done without consuming characters from the stream, if not
the XML parser will not recognized the document as a valid XML. This is not
100% true, but it's close enough (UTF-8 BOM is not handled by all parsers
right now, XmlStreamReader handles it and things work in all parsers).


The XmlStreamReader class handles the charset encoding of XML documents in
Files, raw streams and HTTP streams by offering a wide set of constructors.


By default the charset encoding detection is lenient, the constructor with
the lenient flag can be used for a script (following HTTP MIME and XML
specifications). All this is nicely explained by Mark Pilgrim in his blog, 
Determining the character encoding of a feed.


Originally developed for ROME under
Apache License 2.0.

See Also:
  • XmlStreamWriter
Since:2.0
/**
 * 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>
 * 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>
 * 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>
 * 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="http://diveintomark.org/archives/2004/02/13/xml-media-types">
 * Determining the character encoding of a feed</a>.
 * <p>
 * Originally developed for <a href="http://rome.dev.java.net">ROME</a> under
 * Apache License 2.0.
 *
 * @see org.apache.commons.io.output.XmlStreamWriter
 * @since 2.0
 */
public class XmlStreamReader extends Reader {
    private static final int BUFFER_SIZE = 4096;

    private static final String UTF_8 = "UTF-8";

    private static final String US_ASCII = "US-ASCII";

    private static final String UTF_16BE = "UTF-16BE";

    private static final String UTF_16LE = "UTF-16LE";

    private static final String UTF_32BE = "UTF-32BE";

    private static final String UTF_32LE = "UTF-32LE";

    private static final String UTF_16 = "UTF-16";

    private static final String UTF_32 = "UTF-32";

    private static final String EBCDIC = "CP1047";

    private static final ByteOrderMark[] BOMS = new ByteOrderMark[] {
        ByteOrderMark.UTF_8,
        ByteOrderMark.UTF_16BE,
        ByteOrderMark.UTF_16LE,
        ByteOrderMark.UTF_32BE,
        ByteOrderMark.UTF_32LE
    };

    // UTF_16LE and UTF_32LE have the same two starting BOM bytes.
    private static final ByteOrderMark[] XML_GUESS_BYTES = new ByteOrderMark[] {
        new ByteOrderMark(UTF_8,    0x3C, 0x3F, 0x78, 0x6D),
        new ByteOrderMark(UTF_16BE, 0x00, 0x3C, 0x00, 0x3F),
        new ByteOrderMark(UTF_16LE, 0x3C, 0x00, 0x3F, 0x00),
        new ByteOrderMark(UTF_32BE, 0x00, 0x00, 0x00, 0x3C,
                0x00, 0x00, 0x00, 0x3F, 0x00, 0x00, 0x00, 0x78, 0x00, 0x00, 0x00, 0x6D),
        new ByteOrderMark(UTF_32LE, 0x3C, 0x00, 0x00, 0x00,
                0x3F, 0x00, 0x00, 0x00, 0x78, 0x00, 0x00, 0x00, 0x6D, 0x00, 0x00, 0x00),
        new ByteOrderMark(EBCDIC,   0x4C, 0x6F, 0xA7, 0x94)
    };

    private final Reader reader;

    private final String encoding;

    private final String defaultEncoding;

    
Returns the default encoding to use if none is set in HTTP content-type,
XML prolog and the rules based on content-type are not adequate.


If it is NULL the content-type based rules are used.

Returns:the default encoding to use.
/**
     * 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>
     * If it is NULL the content-type based rules are used.
     *
     * @return the default encoding to use.
     */
    public String getDefaultEncoding() {
        return defaultEncoding;
    }

    
Creates a Reader for a File.


It looks for the UTF-8 BOM first, if none sniffs the XML prolog charset,
if this is also missing defaults to UTF-8.


It does a lenient charset encoding detection, check the constructor with
the lenient parameter for details.

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.
     *
     * @param file File to create a Reader from.
     * @throws IOException thrown if there is a problem reading the file.
     */
    public XmlStreamReader(final File file) throws IOException {
        this(new FileInputStream(file));
    }

    
Creates a Reader for a raw InputStream.


It follows the same logic used for files.


It does a lenient charset encoding detection, check the constructor with
the lenient parameter for details.

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.
     *
     * @param is InputStream to create a Reader from.
     * @throws IOException thrown if there is a problem reading the stream.
     */
    public XmlStreamReader(final InputStream is) throws IOException {
        this(is, true);
    }

    
Creates a Reader for a raw InputStream.


It follows the same logic used for files.


If lenient detection is indicated and the detection above fails as per
specifications it then attempts the following:


If the content type was 'text/html' it replaces it with 'text/xml' and
tries the detection again.


Else if the XML prolog had a charset encoding that encoding is used.


Else if the content type had a charset encoding that encoding is used.


Else 'UTF-8' is used.


If lenient detection is indicated an XmlStreamReaderException is never
thrown.

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.
     *
     * @param is InputStream to create a Reader from.
     * @param lenient indicates if the charset encoding detection should be
     *        relaxed.
     * @throws IOException thrown if there is a problem reading the stream.
     * @throws XmlStreamReaderException thrown if the charset encoding could not
     *         be determined according to the specs.
     */
    public XmlStreamReader(final InputStream is, final boolean lenient) throws IOException {
        this(is, lenient, null);
    }

    
Creates a Reader for a raw InputStream.


It follows the same logic used for files.


If lenient detection is indicated and the detection above fails as per
specifications it then attempts the following:


If the content type was 'text/html' it replaces it with 'text/xml' and
tries the detection again.


Else if the XML prolog had a charset encoding that encoding is used.


Else if the content type had a charset encoding that encoding is used.


Else 'UTF-8' is used.


If lenient detection is indicated an XmlStreamReaderException is never
thrown.

Params:
  • is – InputStream to create a Reader from.
  • lenient – indicates if the charset encoding detection should be
       relaxed.
  • defaultEncoding – The default encoding
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.
     *
     * @param is InputStream to create a Reader from.
     * @param lenient indicates if the charset encoding detection should be
     *        relaxed.
     * @param defaultEncoding The default encoding
     * @throws IOException thrown if there is a problem reading the stream.
     * @throws XmlStreamReaderException thrown if the charset encoding could not
     *         be determined according to the specs.
     */
    public XmlStreamReader(final InputStream is, final boolean lenient, final String defaultEncoding)
            throws IOException {
        this.defaultEncoding = defaultEncoding;
        final BOMInputStream bom = new BOMInputStream(new BufferedInputStream(is, BUFFER_SIZE), false, BOMS);
        final BOMInputStream pis = new BOMInputStream(bom, true, XML_GUESS_BYTES);
        this.encoding = doRawStream(bom, pis, lenient);
        this.reader = new InputStreamReader(pis, encoding);
    }

    
Creates a Reader using the InputStream of a URL.


If the URL is not of type HTTP and there is not 'content-type' header in
the fetched data it uses the same logic used for Files.


If the URL is a HTTP Url or there is a 'content-type' header in the
fetched data it uses the same logic used for an InputStream with
content-type.


It does a lenient charset encoding detection, check the constructor with
the lenient parameter for details.

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.
     *
     * @param url URL to create a Reader from.
     * @throws IOException thrown if there is a problem reading the stream of
     *         the URL.
     */
    public XmlStreamReader(final URL url) throws IOException {
        this(url.openConnection(), null);
    }

    
Creates a Reader using the InputStream of a URLConnection.


If the URLConnection is not of type HttpURLConnection and there is not
'content-type' header in the fetched data it uses the same logic used for
files.


If the URLConnection is a HTTP Url or there is a 'content-type' header in
the fetched data it uses the same logic used for an InputStream with
content-type.


It does a lenient charset encoding detection, check the constructor with
the lenient parameter for details.

Params:
  • conn – URLConnection to create a Reader from.
  • defaultEncoding – The default encoding
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.
     *
     * @param conn URLConnection to create a Reader from.
     * @param defaultEncoding The default encoding
     * @throws IOException thrown if there is a problem reading the stream of
     *         the URLConnection.
     */
    public XmlStreamReader(final URLConnection conn, final String defaultEncoding) throws IOException {
        this.defaultEncoding = defaultEncoding;
        final boolean lenient = true;
        final String contentType = conn.getContentType();
        final InputStream is = conn.getInputStream();
        final BOMInputStream bom = new BOMInputStream(new BufferedInputStream(is, BUFFER_SIZE), false, BOMS);
        final BOMInputStream pis = new BOMInputStream(bom, true, XML_GUESS_BYTES);
        if (conn instanceof HttpURLConnection || contentType != null) {
            this.encoding = doHttpStream(bom, pis, contentType, lenient);
        } else {
            this.encoding = doRawStream(bom, pis, lenient);
        }
        this.reader = new InputStreamReader(pis, encoding);
    }

    
Creates a Reader using an InputStream and the associated content-type
header.


First it checks if the stream has BOM. If there is not BOM checks the
content-type encoding. If there is not content-type encoding checks the
XML prolog encoding. If there is not XML prolog encoding uses the default
encoding mandated by the content-type MIME type.


It does a lenient charset encoding detection, check the constructor with
the lenient parameter for details.

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 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>
     * It does a lenient charset encoding detection, check the constructor with
     * the lenient parameter for details.
     *
     * @param is InputStream to create the reader from.
     * @param httpContentType content-type header to use for the resolution of
     *        the charset encoding.
     * @throws IOException thrown if there is a problem reading the file.
     */
    public XmlStreamReader(final InputStream is, final String httpContentType)
            throws IOException {
        this(is, httpContentType, true);
    }

    
Creates a Reader using an InputStream and the associated content-type
header. This constructor is lenient regarding the encoding detection.


First it checks if the stream has BOM. If there is not BOM checks the
content-type encoding. If there is not content-type encoding checks the
XML prolog encoding. If there is not XML prolog encoding uses the default
encoding mandated by the content-type MIME type.


If lenient detection is indicated and the detection above fails as per
specifications it then attempts the following:


If the content type was 'text/html' it replaces it with 'text/xml' and
tries the detection again.


Else if the XML prolog had a charset encoding that encoding is used.


Else if the content type had a charset encoding that encoding is used.


Else 'UTF-8' is used.


If lenient detection is indicated an XmlStreamReaderException is never
thrown.

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.
  • defaultEncoding – The default encoding
Throws:
/**
     * Creates 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>
     * 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.
     *
     * @param is InputStream to create the reader from.
     * @param httpContentType content-type header to use for the resolution of
     *        the charset encoding.
     * @param lenient indicates if the charset encoding detection should be
     *        relaxed.
     * @param defaultEncoding The default encoding
     * @throws IOException thrown if there is a problem reading the file.
     * @throws XmlStreamReaderException thrown if the charset encoding could not
     *         be determined according to the specs.
     */
    public XmlStreamReader(final InputStream is, final String httpContentType,
            final boolean lenient, final String defaultEncoding) throws IOException {
        this.defaultEncoding = defaultEncoding;
        final BOMInputStream bom = new BOMInputStream(new BufferedInputStream(is, BUFFER_SIZE), false, BOMS);
        final BOMInputStream pis = new BOMInputStream(bom, true, XML_GUESS_BYTES);
        this.encoding = doHttpStream(bom, pis, httpContentType, lenient);
        this.reader = new InputStreamReader(pis, encoding);
    }

    
Creates a Reader using an InputStream and the associated content-type
header. This constructor is lenient regarding the encoding detection.


First it checks if the stream has BOM. If there is not BOM checks the
content-type encoding. If there is not content-type encoding checks the
XML prolog encoding. If there is not XML prolog encoding uses the default
encoding mandated by the content-type MIME type.


If lenient detection is indicated and the detection above fails as per
specifications it then attempts the following:


If the content type was 'text/html' it replaces it with 'text/xml' and
tries the detection again.


Else if the XML prolog had a charset encoding that encoding is used.


Else if the content type had a charset encoding that encoding is used.


Else 'UTF-8' is used.


If lenient detection is indicated an XmlStreamReaderException is never
thrown.

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 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>
     * 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.
     *
     * @param is InputStream to create the reader from.
     * @param httpContentType content-type header to use for the resolution of
     *        the charset encoding.
     * @param lenient indicates if the charset encoding detection should be
     *        relaxed.
     * @throws IOException thrown if there is a problem reading the file.
     * @throws XmlStreamReaderException thrown if the charset encoding could not
     *         be determined according to the specs.
     */
    public XmlStreamReader(final InputStream is, final String httpContentType,
            final boolean lenient) throws IOException {
        this(is, httpContentType, lenient, null);
    }

    
Returns the charset encoding of the XmlStreamReader.

Returns:charset encoding.
/**
     * Returns the charset encoding of the XmlStreamReader.
     *
     * @return charset encoding.
     */
    public String getEncoding() {
        return encoding;
    }

    
Invokes the underlying reader's read(char[], int, int) method.

Params:
  • buf – the buffer to read the characters into
  • offset – The start offset
  • len – The number of bytes to read
Throws:
Returns:the number of characters read or -1 if the end of stream
/**
     * Invokes the underlying reader's <code>read(char[], int, int)</code> method.
     * @param buf the buffer to read the characters into
     * @param offset The start offset
     * @param len The number of bytes to read
     * @return the number of characters read or -1 if the end of stream
     * @throws IOException if an I/O error occurs
     */
    @Override
    public int read(final char[] buf, final int offset, final int len) throws IOException {
        return reader.read(buf, offset, len);
    }

    
Closes the XmlStreamReader stream.

Throws:
  • IOException – thrown if there was a problem closing the stream.
/**
     * Closes the XmlStreamReader stream.
     *
     * @throws IOException thrown if there was a problem closing the stream.
     */
    @Override
    public void close() throws IOException {
        reader.close();
    }

    
Process the raw stream.

Params:
  • bom – BOMInputStream to detect byte order marks
  • pis – BOMInputStream to guess XML encoding
  • lenient – indicates if the charset encoding detection should be
       relaxed.
Throws:
  • IOException – thrown if there is a problem reading the stream.
Returns:the encoding to be used
/**
     * Process the raw stream.
     *
     * @param bom BOMInputStream to detect byte order marks
     * @param pis BOMInputStream to guess XML encoding
     * @param lenient indicates if the charset encoding detection should be
     *        relaxed.
     * @return the encoding to be used
     * @throws IOException thrown if there is a problem reading the stream.
     */
    private String doRawStream(final BOMInputStream bom, final BOMInputStream pis, final boolean lenient)
            throws IOException {
        final String bomEnc      = bom.getBOMCharsetName();
        final String xmlGuessEnc = pis.getBOMCharsetName();
        final String xmlEnc = getXmlProlog(pis, xmlGuessEnc);
        try {
            return calculateRawEncoding(bomEnc, xmlGuessEnc, xmlEnc);
        } catch (final XmlStreamReaderException ex) {
            if (lenient) {
                return doLenientDetection(null, ex);
            } else {
                throw ex;
            }
        }
    }

    
Process a HTTP stream.

Params:
  • bom – BOMInputStream to detect byte order marks
  • pis – BOMInputStream to guess XML encoding
  • httpContentType – The HTTP content type
  • lenient – indicates if the charset encoding detection should be
       relaxed.
Throws:
  • IOException – thrown if there is a problem reading the stream.
Returns:the encoding to be used
/**
     * Process a HTTP stream.
     *
     * @param bom BOMInputStream to detect byte order marks
     * @param pis BOMInputStream to guess XML encoding
     * @param httpContentType The HTTP content type
     * @param lenient indicates if the charset encoding detection should be
     *        relaxed.
     * @return the encoding to be used
     * @throws IOException thrown if there is a problem reading the stream.
     */
    private String doHttpStream(final BOMInputStream bom, final BOMInputStream pis, final String httpContentType,
            final boolean lenient) throws IOException {
        final String bomEnc      = bom.getBOMCharsetName();
        final String xmlGuessEnc = pis.getBOMCharsetName();
        final String xmlEnc = getXmlProlog(pis, xmlGuessEnc);
        try {
            return calculateHttpEncoding(httpContentType, bomEnc,
                    xmlGuessEnc, xmlEnc, lenient);
        } catch (final XmlStreamReaderException ex) {
            if (lenient) {
                return doLenientDetection(httpContentType, ex);
            } else {
                throw ex;
            }
        }
    }

    
Do lenient detection.

Params:
  • httpContentType – content-type header to use for the resolution of
       the charset encoding.
  • ex – The thrown exception
Throws:
  • IOException – thrown if there is a problem reading the stream.
Returns:the encoding
/**
     * Do lenient detection.
     *
     * @param httpContentType content-type header to use for the resolution of
     *        the charset encoding.
     * @param ex The thrown exception
     * @return the encoding
     * @throws IOException thrown if there is a problem reading the stream.
     */
    private String doLenientDetection(String httpContentType,
            XmlStreamReaderException ex) throws IOException {
        if (httpContentType != null && httpContentType.startsWith("text/html")) {
            httpContentType = httpContentType.substring("text/html".length());
            httpContentType = "text/xml" + httpContentType;
            try {
                return calculateHttpEncoding(httpContentType, ex.getBomEncoding(),
                        ex.getXmlGuessEncoding(), ex.getXmlEncoding(), true);
            } catch (final XmlStreamReaderException ex2) {
                ex = ex2;
            }
        }
        String encoding = ex.getXmlEncoding();
        if (encoding == null) {
            encoding = ex.getContentTypeEncoding();
        }
        if (encoding == null) {
            encoding = defaultEncoding == null ? UTF_8 : defaultEncoding;
        }
        return encoding;
    }

    
Calculate the raw encoding.

Params:
  • bomEnc – BOM encoding
  • xmlGuessEnc – XML Guess encoding
  • xmlEnc – XML encoding
Throws:
  • IOException – thrown if there is a problem reading the stream.
Returns:the raw encoding
/**
     * Calculate the raw encoding.
     *
     * @param bomEnc BOM encoding
     * @param xmlGuessEnc XML Guess encoding
     * @param xmlEnc XML encoding
     * @return the raw encoding
     * @throws IOException thrown if there is a problem reading the stream.
     */
    String calculateRawEncoding(final String bomEnc, final String xmlGuessEnc,
            final String xmlEnc) throws IOException {

        // BOM is Null
        if (bomEnc == null) {
            if (xmlGuessEnc == null || xmlEnc == null) {
                return defaultEncoding == null ? UTF_8 : defaultEncoding;
            }
            if (xmlEnc.equals(UTF_16) &&
               (xmlGuessEnc.equals(UTF_16BE) || xmlGuessEnc.equals(UTF_16LE))) {
                return xmlGuessEnc;
            }
            return xmlEnc;
        }

        // BOM is UTF-8
        if (bomEnc.equals(UTF_8)) {
            if (xmlGuessEnc != null && !xmlGuessEnc.equals(UTF_8)) {
                final String msg = MessageFormat.format(RAW_EX_1, bomEnc, xmlGuessEnc, xmlEnc);
                throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
            }
            if (xmlEnc != null && !xmlEnc.equals(UTF_8)) {
                final String msg = MessageFormat.format(RAW_EX_1, bomEnc, xmlGuessEnc, xmlEnc);
                throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
            }
            return bomEnc;
        }

        // BOM is UTF-16BE or UTF-16LE
        if (bomEnc.equals(UTF_16BE) || bomEnc.equals(UTF_16LE)) {
            if (xmlGuessEnc != null && !xmlGuessEnc.equals(bomEnc)) {
                final String msg = MessageFormat.format(RAW_EX_1, bomEnc, xmlGuessEnc, xmlEnc);
                throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
            }
            if (xmlEnc != null && !xmlEnc.equals(UTF_16) && !xmlEnc.equals(bomEnc)) {
                final String msg = MessageFormat.format(RAW_EX_1, bomEnc, xmlGuessEnc, xmlEnc);
                throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
            }
            return bomEnc;
        }

        // BOM is UTF-32BE or UTF-32LE
        if (bomEnc.equals(UTF_32BE) || bomEnc.equals(UTF_32LE)) {
            if (xmlGuessEnc != null && !xmlGuessEnc.equals(bomEnc)) {
                final String msg = MessageFormat.format(RAW_EX_1, bomEnc, xmlGuessEnc, xmlEnc);
                throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
            }
            if (xmlEnc != null && !xmlEnc.equals(UTF_32) && !xmlEnc.equals(bomEnc)) {
                final String msg = MessageFormat.format(RAW_EX_1, bomEnc, xmlGuessEnc, xmlEnc);
                throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
            }
            return bomEnc;
        }

        // BOM is something else
        final String msg = MessageFormat.format(RAW_EX_2, bomEnc, xmlGuessEnc, xmlEnc);
        throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
    }


    
Calculate the HTTP encoding.

Params:
  • httpContentType – The HTTP content type
  • bomEnc – BOM encoding
  • xmlGuessEnc – XML Guess encoding
  • xmlEnc – XML encoding
  • lenient – indicates if the charset encoding detection should be
       relaxed.
Throws:
  • IOException – thrown if there is a problem reading the stream.
Returns:the HTTP encoding
/**
     * Calculate the HTTP encoding.
     *
     * @param httpContentType The HTTP content type
     * @param bomEnc BOM encoding
     * @param xmlGuessEnc XML Guess encoding
     * @param xmlEnc XML encoding
     * @param lenient indicates if the charset encoding detection should be
     *        relaxed.
     * @return the HTTP encoding
     * @throws IOException thrown if there is a problem reading the stream.
     */
    String calculateHttpEncoding(final String httpContentType,
            final String bomEnc, final String xmlGuessEnc, final String xmlEnc,
            final boolean lenient) throws IOException {

        // Lenient and has XML encoding
        if (lenient && xmlEnc != null) {
            return xmlEnc;
        }

        // Determine mime/encoding content types from HTTP Content Type
        final String cTMime = getContentTypeMime(httpContentType);
        final String cTEnc  = getContentTypeEncoding(httpContentType);
        final boolean appXml  = isAppXml(cTMime);
        final boolean textXml = isTextXml(cTMime);

        // Mime type NOT "application/xml" or "text/xml"
        if (!appXml && !textXml) {
            final String msg = MessageFormat.format(HTTP_EX_3, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
            throw new XmlStreamReaderException(msg, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
        }

        // No content type encoding
        if (cTEnc == null) {
            if (appXml) {
                return calculateRawEncoding(bomEnc, xmlGuessEnc, xmlEnc);
            } else {
                return defaultEncoding == null ? US_ASCII : defaultEncoding;
            }
        }

        // UTF-16BE or UTF-16LE content type encoding
        if (cTEnc.equals(UTF_16BE) || cTEnc.equals(UTF_16LE)) {
            if (bomEnc != null) {
                final String msg = MessageFormat.format(HTTP_EX_1, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
                throw new XmlStreamReaderException(msg, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
            }
            return cTEnc;
        }

        // UTF-16 content type encoding
        if (cTEnc.equals(UTF_16)) {
            if (bomEnc != null && bomEnc.startsWith(UTF_16)) {
                return bomEnc;
            }
            final String msg = MessageFormat.format(HTTP_EX_2, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
            throw new XmlStreamReaderException(msg, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
        }

        // UTF-32BE or UTF-132E content type encoding
        if (cTEnc.equals(UTF_32BE) || cTEnc.equals(UTF_32LE)) {
            if (bomEnc != null) {
                final String msg = MessageFormat.format(HTTP_EX_1, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
                throw new XmlStreamReaderException(msg, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
            }
            return cTEnc;
        }

        // UTF-32 content type encoding
        if (cTEnc.equals(UTF_32)) {
            if (bomEnc != null && bomEnc.startsWith(UTF_32)) {
                return bomEnc;
            }
            final String msg = MessageFormat.format(HTTP_EX_2, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
            throw new XmlStreamReaderException(msg, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
        }

        return cTEnc;
    }

    
Returns MIME type or NULL if httpContentType is NULL.

Params:
  • httpContentType – the HTTP content type
Returns:The mime content type
/**
     * Returns MIME type or NULL if httpContentType is NULL.
     *
     * @param httpContentType the HTTP content type
     * @return The mime content type
     */
    static String getContentTypeMime(final String httpContentType) {
        String mime = null;
        if (httpContentType != null) {
            final int i = httpContentType.indexOf(";");
            if (i >= 0) {
                mime = httpContentType.substring(0, i);
            } else {
                mime = httpContentType;
            }
            mime = mime.trim();
        }
        return mime;
    }

    private static final Pattern CHARSET_PATTERN = Pattern
            .compile("charset=[\"']?([.[^; \"']]*)[\"']?");

    
Returns charset parameter value, NULL if not present, NULL if
httpContentType is NULL.

Params:
  • httpContentType – the HTTP content type
Returns:The content type encoding (upcased)
/**
     * Returns charset parameter value, NULL if not present, NULL if
     * httpContentType is NULL.
     *
     * @param httpContentType the HTTP content type
     * @return The content type encoding (upcased)
     */
    static String getContentTypeEncoding(final String httpContentType) {
        String encoding = null;
        if (httpContentType != null) {
            final int i = httpContentType.indexOf(";");
            if (i > -1) {
                final String postMime = httpContentType.substring(i + 1);
                final Matcher m = CHARSET_PATTERN.matcher(postMime);
                encoding = m.find() ? m.group(1) : null;
                encoding = encoding != null ? encoding.toUpperCase(Locale.US) : null;
            }
        }
        return encoding;
    }

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

    
Returns the encoding declared in the , NULL if none.

Params:
  • is – InputStream to create the reader from.
  • guessedEnc – guessed encoding
Throws:
  • IOException – thrown if there is a problem reading the stream.
Returns:the encoding declared in the 
/**
     * Returns the encoding declared in the <?xml encoding=...?>, NULL if none.
     *
     * @param is 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 is, final String guessedEnc)
            throws IOException {
        String encoding = null;
        if (guessedEnc != null) {
            final byte[] bytes = new byte[BUFFER_SIZE];
            is.mark(BUFFER_SIZE);
            int offset = 0;
            int max = BUFFER_SIZE;
            int c = is.read(bytes, offset, max);
            int firstGT = -1;
            String xmlProlog = ""; // avoid possible NPE warning (cannot happen; this just silences the warning)
            while (c != -1 && firstGT == -1 && offset < BUFFER_SIZE) {
                offset += c;
                max -= c;
                c = is.read(bytes, offset, max);
                xmlProlog = new String(bytes, 0, offset, guessedEnc);
                firstGT = xmlProlog.indexOf('>');
            }
            if (firstGT == -1) {
                if (c == -1) {
                    throw new IOException("Unexpected end of XML stream");
                } else {
                    throw new IOException(
                            "XML prolog or ROOT element not found on first "
                                    + offset + " bytes");
                }
            }
            final int bytesRead = offset;
            if (bytesRead > 0) {
                is.reset();
                final BufferedReader bReader = new BufferedReader(new StringReader(
                        xmlProlog.substring(0, firstGT + 1)));
                final StringBuffer prolog = new StringBuffer();
                String line = bReader.readLine();
                while (line != null) {
                    prolog.append(line);
                    line = bReader.readLine();
                }
                final Matcher m = ENCODING_PATTERN.matcher(prolog);
                if (m.find()) {
                    encoding = m.group(1).toUpperCase();
                    encoding = encoding.substring(1, encoding.length() - 1);
                }
            }
        }
        return encoding;
    }

    
Indicates if the MIME type belongs to the APPLICATION XML family.

Params:
  • mime – The mime type
Returns:true if the mime type belongs to the APPLICATION XML family,
otherwise false
/**
     * Indicates if the MIME type belongs to the APPLICATION XML family.
     *
     * @param mime The mime type
     * @return true if the mime type belongs to the APPLICATION XML family,
     * otherwise false
     */
    static boolean isAppXml(final String mime) {
        return mime != null &&
               (mime.equals("application/xml") ||
                mime.equals("application/xml-dtd") ||
                mime.equals("application/xml-external-parsed-entity") ||
               mime.startsWith("application/") && mime.endsWith("+xml"));
    }

    
Indicates if the MIME type belongs to the TEXT XML family.

Params:
  • mime – The mime type
Returns:true if the mime type belongs to the TEXT XML family,
otherwise false
/**
     * Indicates if the MIME type belongs to the TEXT XML family.
     *
     * @param mime The mime type
     * @return true if the mime type belongs to the TEXT XML family,
     * otherwise false
     */
    static boolean isTextXml(final String mime) {
        return mime != null &&
              (mime.equals("text/xml") ||
               mime.equals("text/xml-external-parsed-entity") ||
              mime.startsWith("text/") && mime.endsWith("+xml"));
    }

    private static final String RAW_EX_1 =
        "Invalid encoding, BOM [{0}] XML guess [{1}] XML prolog [{2}] encoding mismatch";

    private static final String RAW_EX_2 =
        "Invalid encoding, BOM [{0}] XML guess [{1}] XML prolog [{2}] unknown BOM";

    private static final String HTTP_EX_1 =
        "Invalid encoding, CT-MIME [{0}] CT-Enc [{1}] BOM [{2}] XML guess [{3}] XML prolog [{4}], BOM must be NULL";

    private static final String HTTP_EX_2 =
        "Invalid encoding, CT-MIME [{0}] CT-Enc [{1}] BOM [{2}] XML guess [{3}] XML prolog [{4}], encoding mismatch";

    private static final String HTTP_EX_3 =
        "Invalid encoding, CT-MIME [{0}] CT-Enc [{1}] BOM [{2}] XML guess [{3}] XML prolog [{4}], Invalid MIME";

}