org.codehaus.plexus.util.xml.XmlReader Maven / Gradle / Ivy
/*
* 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 attemtps 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
*/
public class XmlReader extends Reader
{
private static final int BUFFER_SIZE = 4096;
private static final String UTF_8 = "UTF-8";
private static final String US_ASCII = "US-ASCII";
private static final String UTF_16BE = "UTF-16BE";
private static final String UTF_16LE = "UTF-16LE";
private static final String UTF_16 = "UTF-16";
private static final String EBCDIC = "CP1047";
private static String _staticDefaultEncoding = null;
private Reader _reader;
private String _encoding;
private String _defaultEncoding;
/**
* Sets the default encoding to use if none is set in HTTP content-type, XML prolog and the rules based on
* content-type are not adequate.
If it is set to NULL the content-type based rules are used. By default
* it is NULL.
*
* @param encoding
* charset encoding to default to.
*/
public static void setDefaultEncoding( String encoding )
{
_staticDefaultEncoding = encoding;
}
/**
* Returns the default encoding to use if none is set in HTTP content-type, XML prolog and the rules based on
* content-type are not adequate. If it is NULL the content-type based rules are used.
*
* @return the default encoding to use.
*/
public static String getDefaultEncoding()
{
return _staticDefaultEncoding;
}
/**
* Creates a Reader for a File.
*
* It looks for the UTF-8 BOM first, if none sniffs the XML prolog charset, if this is also missing defaults to
* UTF-8.
*
* It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
*
*
* @param file
* File to create a Reader from.
* @throws IOException
* thrown if there is a problem reading the file.
*
*/
public XmlReader( File file ) throws IOException
{
this( 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.
*
*
* @param is
* InputStream to create a Reader from.
* @throws IOException
* thrown if there is a problem reading the stream.
*
*/
public XmlReader( InputStream is ) throws IOException
{
this( is, true );
}
/**
* Creates a Reader for a raw InputStream.
*
* It follows the same logic used for files.
*
* If lenient detection is indicated and the detection above fails as per specifications it then attempts the
* following:
*
* If the content type was 'text/html' it replaces it with 'text/xml' and tries the detection again.
*
* Else if the XML prolog had a charset encoding that encoding is used.
*
* Else if the content type had a charset encoding that encoding is used.
*
* Else 'UTF-8' is used.
*
* If lenient detection is indicated an XmlStreamReaderException is never thrown.
*
*
* @param is
* InputStream to create a Reader from.
* @param lenient
* indicates if the charset encoding detection should be relaxed.
* @throws IOException
* thrown if there is a problem reading the stream.
* @throws XmlStreamReaderException
* thrown if the charset encoding could not be determined according to the specs.
*
*/
public XmlReader( InputStream is, boolean lenient ) throws IOException, XmlStreamReaderException
{
_defaultEncoding = _staticDefaultEncoding;
try
{
doRawStream( is, lenient );
}
catch ( XmlStreamReaderException ex )
{
if ( !lenient )
{
throw ex;
}
else
{
doLenientDetection( null, ex );
}
}
}
/**
* Creates a Reader using the InputStream of a URL.
*
* If the URL is not of type HTTP and there is not 'content-type' header in the fetched data it uses the same logic
* used for Files.
*
* If the URL is a HTTP Url or there is a 'content-type' header in the fetched data it uses the same logic used for
* an InputStream with content-type.
*
* It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
*
*
* @param url
* URL to create a Reader from.
* @throws IOException
* thrown if there is a problem reading the stream of the URL.
*
*/
public XmlReader( URL url ) throws IOException
{
this( url.openConnection() );
}
/**
* Creates a Reader using the InputStream of a URLConnection.
*
* If the URLConnection is not of type HttpURLConnection and there is not 'content-type' header in the fetched data
* it uses the same logic used for files.
*
* If the URLConnection is a HTTP Url or there is a 'content-type' header in the fetched data it uses the same logic
* used for an InputStream with content-type.
*
* It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
*
*
* @param conn
* URLConnection to create a Reader from.
* @throws IOException
* thrown if there is a problem reading the stream of the URLConnection.
*
*/
public XmlReader( URLConnection conn ) throws IOException
{
_defaultEncoding = _staticDefaultEncoding;
boolean lenient = true;
if ( conn instanceof HttpURLConnection )
{
try
{
doHttpStream( conn.getInputStream(), conn.getContentType(), lenient );
}
catch ( XmlStreamReaderException ex )
{
doLenientDetection( conn.getContentType(), ex );
}
}
else if ( conn.getContentType() != null )
{
try
{
doHttpStream( conn.getInputStream(), conn.getContentType(), lenient );
}
catch ( XmlStreamReaderException ex )
{
doLenientDetection( conn.getContentType(), ex );
}
}
else
{
try
{
doRawStream( conn.getInputStream(), lenient );
}
catch ( XmlStreamReaderException ex )
{
doLenientDetection( null, ex );
}
}
}
/**
* Creates a Reader using an InputStream an the associated content-type header.
*
* First it checks if the stream has BOM. If there is not BOM checks the content-type encoding. If there is not
* content-type encoding checks the XML prolog encoding. If there is not XML prolog encoding uses the default
* encoding mandated by the content-type MIME type.
*
* It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
*
*
* @param is
* InputStream to create the reader from.
* @param httpContentType
* content-type header to use for the resolution of the charset encoding.
* @throws IOException
* thrown if there is a problem reading the file.
*
*/
public XmlReader( InputStream is, String httpContentType ) throws IOException
{
this( is, httpContentType, true );
}
/**
* Creates a Reader using an InputStream an the associated content-type header. This constructor is lenient
* regarding the encoding detection.
*
* First it checks if the stream has BOM. If there is not BOM checks the content-type encoding. If there is not
* content-type encoding checks the XML prolog encoding. If there is not XML prolog encoding uses the default
* encoding mandated by the content-type MIME type.
*
* If lenient detection is indicated and the detection above fails as per specifications it then attempts the
* following:
*
* If the content type was 'text/html' it replaces it with 'text/xml' and tries the detection again.
*
* Else if the XML prolog had a charset encoding that encoding is used.
*
* Else if the content type had a charset encoding that encoding is used.
*
* Else 'UTF-8' is used.
*
* If lenient detection is indicated an XmlStreamReaderException is never thrown.
*
*
* @param is
* InputStream to create the reader from.
* @param httpContentType
* content-type header to use for the resolution of the charset encoding.
* @param lenient
* indicates if the charset encoding detection should be relaxed.
* @throws IOException
* thrown if there is a problem reading the file.
* @throws XmlStreamReaderException
* thrown if the charset encoding could not be determined according to the specs.
*
*/
public XmlReader( InputStream is, String httpContentType, boolean lenient, String defaultEncoding )
throws IOException, XmlStreamReaderException
{
_defaultEncoding = ( defaultEncoding == null ) ? _staticDefaultEncoding : defaultEncoding;
try
{
doHttpStream( is, httpContentType, lenient );
}
catch ( XmlStreamReaderException ex )
{
if ( !lenient )
{
throw ex;
}
else
{
doLenientDetection( httpContentType, ex );
}
}
}
/**
* Creates a Reader using an InputStream an the associated content-type header. This constructor is lenient
* regarding the encoding detection.
*
* First it checks if the stream has BOM. If there is not BOM checks the content-type encoding. If there is not
* content-type encoding checks the XML prolog encoding. If there is not XML prolog encoding uses the default
* encoding mandated by the content-type MIME type.
*
* If lenient detection is indicated and the detection above fails as per specifications it then attempts the
* following:
*
* If the content type was 'text/html' it replaces it with 'text/xml' and tries the detection again.
*
* Else if the XML prolog had a charset encoding that encoding is used.
*
* Else if the content type had a charset encoding that encoding is used.
*
* Else 'UTF-8' is used.
*
* If lenient detection is indicated an XmlStreamReaderException is never thrown.
*
*
* @param is
* InputStream to create the reader from.
* @param httpContentType
* content-type header to use for the resolution of the charset encoding.
* @param lenient
* indicates if the charset encoding detection should be relaxed.
* @throws IOException
* thrown if there is a problem reading the file.
* @throws XmlStreamReaderException
* thrown if the charset encoding could not be determined according to the specs.
*
*/
public XmlReader( InputStream is, String httpContentType, boolean lenient ) throws IOException, XmlStreamReaderException
{
this( is, httpContentType, lenient, null );
}
private void doLenientDetection( String httpContentType, XmlStreamReaderException ex ) throws IOException
{
if ( httpContentType != null )
{
if ( httpContentType.startsWith( "text/html" ) )
{
httpContentType = httpContentType.substring( "text/html".length() );
httpContentType = "text/xml" + httpContentType;
try
{
doHttpStream( ex.getInputStream(), httpContentType, true );
ex = null;
}
catch ( XmlStreamReaderException ex2 )
{
ex = ex2;
}
}
}
if ( ex != null )
{
String encoding = ex.getXmlEncoding();
if ( encoding == null )
{
encoding = ex.getContentTypeEncoding();
}
if ( encoding == null )
{
encoding = ( _defaultEncoding == null ) ? UTF_8 : _defaultEncoding;
}
prepareReader( ex.getInputStream(), encoding );
}
}
/**
* Returns the charset encoding of the XmlReader.
*
*
* @return charset encoding.
*
*/
public String getEncoding()
{
return _encoding;
}
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.
*
*/
public void close() throws IOException
{
_reader.close();
}
private void doRawStream( InputStream is, boolean lenient ) throws IOException
{
BufferedInputStream pis = new BufferedInputStream( is, BUFFER_SIZE );
String bomEnc = getBOMEncoding( pis );
String xmlGuessEnc = getXMLGuessEncoding( pis );
String xmlEnc = getXmlProlog( pis, xmlGuessEnc );
String encoding = calculateRawEncoding( bomEnc, xmlGuessEnc, xmlEnc, pis );
prepareReader( pis, encoding );
}
private void doHttpStream( InputStream is, String httpContentType, boolean lenient ) throws IOException
{
BufferedInputStream pis = new BufferedInputStream( is, BUFFER_SIZE );
String cTMime = getContentTypeMime( httpContentType );
String cTEnc = getContentTypeEncoding( httpContentType );
String bomEnc = getBOMEncoding( pis );
String xmlGuessEnc = getXMLGuessEncoding( pis );
String xmlEnc = getXmlProlog( pis, xmlGuessEnc );
String encoding = calculateHttpEncoding( cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc, pis, lenient );
prepareReader( pis, encoding );
}
private void prepareReader( InputStream is, String encoding ) throws IOException
{
_reader = new InputStreamReader( is, encoding );
_encoding = encoding;
}
// InputStream is passed for XmlStreamReaderException creation only
private String calculateRawEncoding( String bomEnc, String xmlGuessEnc, String xmlEnc, InputStream is )
throws IOException
{
String encoding;
if ( bomEnc == null )
{
if ( xmlGuessEnc == null || xmlEnc == null )
{
encoding = ( _defaultEncoding == null ) ? UTF_8 : _defaultEncoding;
}
else if ( xmlEnc.equals( UTF_16 ) && ( xmlGuessEnc.equals( UTF_16BE ) || xmlGuessEnc.equals( UTF_16LE ) ) )
{
encoding = xmlGuessEnc;
}
else
{
encoding = xmlEnc;
}
}
else if ( bomEnc.equals( UTF_8 ) )
{
if ( xmlGuessEnc != null && !xmlGuessEnc.equals( UTF_8 ) )
{
throw new XmlStreamReaderException( RAW_EX_1.format( new Object[] { bomEnc, xmlGuessEnc, xmlEnc } ), bomEnc,
xmlGuessEnc, xmlEnc, is );
}
if ( xmlEnc != null && !xmlEnc.equals( UTF_8 ) )
{
throw new XmlStreamReaderException( RAW_EX_1.format( new Object[] { bomEnc, xmlGuessEnc, xmlEnc } ), bomEnc,
xmlGuessEnc, xmlEnc, is );
}
encoding = UTF_8;
}
else if ( bomEnc.equals( UTF_16BE ) || bomEnc.equals( UTF_16LE ) )
{
if ( xmlGuessEnc != null && !xmlGuessEnc.equals( bomEnc ) )
{
throw new IOException( RAW_EX_1.format( new Object[] { bomEnc, xmlGuessEnc, xmlEnc } ) );
}
if ( xmlEnc != null && !xmlEnc.equals( UTF_16 ) && !xmlEnc.equals( bomEnc ) )
{
throw new XmlStreamReaderException( RAW_EX_1.format( new Object[] { bomEnc, xmlGuessEnc, xmlEnc } ), bomEnc,
xmlGuessEnc, xmlEnc, is );
}
encoding = bomEnc;
}
else
{
throw new XmlStreamReaderException( RAW_EX_2.format( new Object[] { bomEnc, xmlGuessEnc, xmlEnc } ), bomEnc,
xmlGuessEnc, xmlEnc, is );
}
return encoding;
}
// InputStream is passed for XmlStreamReaderException creation only
private String calculateHttpEncoding( String cTMime, String cTEnc, String bomEnc, String xmlGuessEnc,
String xmlEnc, InputStream is, boolean lenient ) throws IOException
{
String encoding;
if ( lenient & xmlEnc != null )
{
encoding = xmlEnc;
}
else
{
boolean appXml = isAppXml( cTMime );
boolean textXml = isTextXml( cTMime );
if ( appXml || textXml )
{
if ( cTEnc == null )
{
if ( appXml )
{
encoding = calculateRawEncoding( bomEnc, xmlGuessEnc, xmlEnc, is );
}
else
{
encoding = ( _defaultEncoding == null ) ? US_ASCII : _defaultEncoding;
}
}
else if ( bomEnc != null && ( cTEnc.equals( UTF_16BE ) || cTEnc.equals( UTF_16LE ) ) )
{
throw new XmlStreamReaderException( HTTP_EX_1.format( new Object[] { cTMime, cTEnc, bomEnc, xmlGuessEnc,
xmlEnc } ), cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc, is );
}
else if ( cTEnc.equals( UTF_16 ) )
{
if ( bomEnc != null && bomEnc.startsWith( UTF_16 ) )
{
encoding = bomEnc;
}
else
{
throw new XmlStreamReaderException( HTTP_EX_2.format( new Object[] { cTMime, cTEnc, bomEnc,
xmlGuessEnc, xmlEnc } ), cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc, is );
}
}
else
{
encoding = cTEnc;
}
}
else
{
throw new XmlStreamReaderException( HTTP_EX_3.format( new Object[] { cTMime, cTEnc, bomEnc, xmlGuessEnc,
xmlEnc } ), cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc, is );
}
}
return encoding;
}
// returns MIME type or NULL if httpContentType is NULL
private static String getContentTypeMime( String httpContentType )
{
String mime = null;
if ( httpContentType != null )
{
int i = httpContentType.indexOf( ";" );
mime = ( ( i == -1 ) ? httpContentType : httpContentType.substring( 0, i ) ).trim();
}
return mime;
}
private static final Pattern CHARSET_PATTERN = Pattern.compile( "charset=([.[^; ]]*)" );
// returns charset parameter value, NULL if not present, NULL if httpContentType is NULL
private static String getContentTypeEncoding( String httpContentType )
{
String encoding = null;
if ( httpContentType != null )
{
int i = httpContentType.indexOf( ";" );
if ( i > -1 )
{
String postMime = httpContentType.substring( i + 1 );
Matcher m = CHARSET_PATTERN.matcher( postMime );
encoding = ( m.find() ) ? m.group( 1 ) : null;
encoding = ( encoding != null ) ? encoding.toUpperCase( Locale.ENGLISH ) : null;
}
}
return encoding;
}
// returns the BOM in the stream, NULL if not present,
// if there was BOM the in the stream it is consumed
private static String getBOMEncoding( BufferedInputStream is ) throws IOException
{
String encoding = null;
int[] bytes = new int[3];
is.mark( 3 );
bytes[0] = is.read();
bytes[1] = is.read();
bytes[2] = is.read();
if ( bytes[0] == 0xFE && bytes[1] == 0xFF )
{
encoding = UTF_16BE;
is.reset();
is.read();
is.read();
}
else if ( bytes[0] == 0xFF && bytes[1] == 0xFE )
{
encoding = UTF_16LE;
is.reset();
is.read();
is.read();
}
else if ( bytes[0] == 0xEF && bytes[1] == 0xBB && bytes[2] == 0xBF )
{
encoding = UTF_8;
}
else
{
is.reset();
}
return encoding;
}
// returns the best guess for the encoding by looking the first bytes of the stream, ', NULL if none
private static String getXmlProlog( BufferedInputStream is, String guessedEnc ) throws IOException
{
String encoding = null;
if ( guessedEnc != null )
{
byte[] bytes = new byte[BUFFER_SIZE];
is.mark( BUFFER_SIZE );
int offset = 0;
int max = BUFFER_SIZE;
int c = is.read( bytes, offset, max );
int firstGT = -1;
String xmlProlog = null;
while ( c != -1 && firstGT == -1 && offset < BUFFER_SIZE )
{
offset += c;
max -= c;
c = is.read( bytes, offset, max );
xmlProlog = new String( bytes, 0, offset, guessedEnc );
firstGT = xmlProlog.indexOf( '>' );
}
if ( firstGT == -1 )
{
if ( c == -1 )
{
throw new IOException( "Unexpected end of XML stream" );
}
else
{
throw new IOException( "XML prolog or ROOT element not found on first " + offset + " bytes" );
}
}
int bytesRead = offset;
if ( bytesRead > 0 )
{
is.reset();
BufferedReader bReader = new BufferedReader( new StringReader( xmlProlog.substring( 0, firstGT + 1 ) ) );
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( 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" );
}