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Commons IO example source code file (XmlStreamReader.java)

This example Commons IO source code file (XmlStreamReader.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons IO tags/keywords

bom, bominputstream, byteordermark, invalid, io, ioexception, ioexception, net, network, object, regex, string, string, text, xml, xml, xmlstreamreader, xmlstreamreaderexception, xmlstreamreaderexception

The Commons IO XmlStreamReader.java source code

/*
 * 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.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.io.ByteOrderMark;

/**
 * Character stream that handles all the necessary Voodo 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 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>
 * Originally developed for <a href="http://rome.dev.java.net">ROME under
 * Apache License 2.0.
 *
 * @author Alejandro Abdelnur
 * @version $Id: XmlStreamReader.java 1021884 2010-10-12 18:49:16Z ggregory $
 * @see org.apache.commons.io.output.XmlStreamWriter
 * @since Commons IO 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_16 = "UTF-16";

    private static final String EBCDIC = "CP1047";

    private static final ByteOrderMark[] BOMS = new ByteOrderMark[] {
        ByteOrderMark.UTF_8,
        ByteOrderMark.UTF_16BE,
        ByteOrderMark.UTF_16LE
    };
    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(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.
     * <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.
     * <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(File file) throws IOException {
        this(new FileInputStream(file));
    }

    /**
     * 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(InputStream is) throws IOException {
        this(is, true);
    }

    /**
     * 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(InputStream is, boolean lenient) throws IOException {
        this(is, lenient, null);
    }

    /**
     * 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(InputStream is, boolean lenient, String defaultEncoding) throws IOException {
        this.defaultEncoding = defaultEncoding;
        this.encoding = doRawStream(is, lenient);
        this.reader = new InputStreamReader(is, encoding);
    }

    /**
     * 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(URL url) throws IOException {
        this(url.openConnection(), null);
    }

    /**
     * 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(URLConnection conn, String defaultEncoding) throws IOException {
        this.defaultEncoding = defaultEncoding;
        boolean lenient = true;
        String contentType = conn.getContentType();
        InputStream is = conn.getInputStream();
        if (conn instanceof HttpURLConnection || contentType != null) {
            this.encoding = doHttpStream(is, contentType, lenient);
        } else {
            this.encoding = doRawStream(is, lenient);
        }
        this.reader = new InputStreamReader(is, encoding);
    }

    /**
     * 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.
     *
     * @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(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.
     * <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(InputStream is, String httpContentType,
            boolean lenient, String defaultEncoding) throws IOException {
        this.defaultEncoding = defaultEncoding;
        this.encoding = doHttpStream(is, httpContentType, lenient);
        this.reader = new InputStreamReader(is, encoding);
    }

    /**
     * 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.
     *
     * @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(InputStream is, String httpContentType,
            boolean lenient) throws IOException {
        this(is, httpContentType, lenient, null);
    }

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

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

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

    /**
     * Process the raw stream.
     *
     * @param is InputStream to create the reader from.
     * @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(InputStream is, boolean lenient)
            throws IOException {
        BOMInputStream bom = new BOMInputStream(new BufferedInputStream(is, BUFFER_SIZE), false, BOMS);
        BOMInputStream pis = new BOMInputStream(bom, true, XML_GUESS_BYTES);
        String bomEnc      = bom.getBOMCharsetName();
        String xmlGuessEnc = pis.getBOMCharsetName();
        String xmlEnc = getXmlProlog(pis, xmlGuessEnc);
        try {
            return calculateRawEncoding(bomEnc, xmlGuessEnc, xmlEnc);
        } catch (XmlStreamReaderException ex) {
            if (lenient) {
                return doLenientDetection(null, is, ex);
            } else {
                throw ex;
            }
        }
    }

    /**
     * Process a HTTP stream.
     *
     * @param is InputStream to create the reader from.
     * @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(InputStream is, String httpContentType,
            boolean lenient) throws IOException {
        BOMInputStream bom = new BOMInputStream(new BufferedInputStream(is, BUFFER_SIZE), false, BOMS);
        BOMInputStream pis = new BOMInputStream(bom, true, XML_GUESS_BYTES);
        String bomEnc      = bom.getBOMCharsetName();
        String xmlGuessEnc = pis.getBOMCharsetName();
        String xmlEnc = getXmlProlog(pis, xmlGuessEnc);
        try {
            return calculateHttpEncoding(httpContentType, bomEnc,
                    xmlGuessEnc, xmlEnc, lenient);
        } catch (XmlStreamReaderException ex) {
            if (lenient) {
                return doLenientDetection(httpContentType, is, ex);
            } else {
                throw ex;
            }
        }
    }

    /**
     * Do lenient detection.
     *
     * @param httpContentType content-type header to use for the resolution of
     *        the charset encoding.
     * @param is the unconsumed InputStream
     * @param ex The thrown exception
     * @return the encoding
     * @throws IOException thrown if there is a problem reading the stream.
     */
    private String doLenientDetection(String httpContentType, InputStream is,
            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 (XmlStreamReaderException ex2) {
                ex = ex2;
            }
        }
        String encoding = ex.getXmlEncoding();
        if (encoding == null) {
            encoding = ex.getContentTypeEncoding();
        }
        if (encoding == null) {
            encoding = (defaultEncoding == null) ? UTF_8 : defaultEncoding;
        }
        return encoding;
    }

    /**
     * Calculate the raw encoding.
     *
     * @param bomEnc BOM encoding
     * @param xmlGuessEnc XML Guess encoding
     * @param xmlEnc XML encoding
     * @return the raw encoding
     * @throws IOException thrown if there is a problem reading the stream.
     */
    String calculateRawEncoding(String bomEnc, String xmlGuessEnc,
            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)) {
                String msg = MessageFormat.format(RAW_EX_1, new Object[] { bomEnc, xmlGuessEnc, xmlEnc });
                throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
            }
            if (xmlEnc != null && !xmlEnc.equals(UTF_8)) {
                String msg = MessageFormat.format(RAW_EX_1, new Object[] { 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)) {
                String msg = MessageFormat.format(RAW_EX_1, new Object[] { bomEnc, xmlGuessEnc, xmlEnc });
                throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
            }
            if (xmlEnc != null && !xmlEnc.equals(UTF_16) && !xmlEnc.equals(bomEnc)) {
                String msg = MessageFormat.format(RAW_EX_1, new Object[] { bomEnc, xmlGuessEnc, xmlEnc });
                throw new XmlStreamReaderException(msg, bomEnc, xmlGuessEnc, xmlEnc);
            }
            return bomEnc;
        }

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


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

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

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

        // Mime type NOT "application/xml" or "text/xml"
        if (!appXml && !textXml) {
            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) {
                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;
            }
            String msg = MessageFormat.format(HTTP_EX_2, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
            throw new XmlStreamReaderException(msg, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
        }

        return cTEnc;
    }

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

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

    /**
     * Returns charset parameter value, NULL if not present, NULL if
     * httpContentType is NULL.
     *
     * @param httpContentType the HTTP content type
     * @return The content type encoding
     */
    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() : null;
            }
        }
        return encoding;
    }

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

    /**
     * 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(InputStream 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)));
                StringBuffer prolog = new StringBuffer();
                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();
                    encoding = encoding.substring(1, encoding.length() - 1);
                }
            }
        }
        return encoding;
    }

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

    /**
     * Indicates if the MIME type belongs to the TEXT XML family.
     * 
     * @param mime The mime type
     * @return true if the mime type belongs to the TEXT XML family,
     * otherwise false
     */
    static boolean isTextXml(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";

}

Other Commons IO examples (source code examples)

Here is a short list of links related to this Commons IO XmlStreamReader.java source code file:



my book on functional programming

 

new blog posts

 

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