org.codehaus.plexus.util.xml

Class XmlReader

public class XmlReader extends Reader

Deprecated: use XmlStreamReader

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.

Since: 1.4.3

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)

Author: Alejandro Abdelnur

Field Summary
static intBUFFER_SIZE
static PatternCHARSET_PATTERN
static StringEBCDIC
static PatternENCODING_PATTERN
static MessageFormatHTTP_EX_1
static MessageFormatHTTP_EX_2
static MessageFormatHTTP_EX_3
static MessageFormatRAW_EX_1
static MessageFormatRAW_EX_2
static StringUS_ASCII
static StringUTF_16
static StringUTF_16BE
static StringUTF_16LE
static StringUTF_8
String_defaultEncoding
String_encoding
Reader_reader
static String_staticDefaultEncoding
Constructor Summary
XmlReader(File file)
Creates a Reader for a File.
XmlReader(InputStream is)
Creates a Reader for a raw InputStream.
XmlReader(InputStream is, boolean lenient)
Creates a Reader for a raw InputStream.
XmlReader(URL url)
Creates a Reader using the InputStream of a URL.
XmlReader(URLConnection conn)
Creates a Reader using the InputStream of a URLConnection.
XmlReader(InputStream is, String httpContentType)
Creates a Reader using an InputStream an the associated content-type header.
XmlReader(InputStream is, String httpContentType, boolean lenient, String defaultEncoding)
Creates a Reader using an InputStream an the associated content-type header.
XmlReader(InputStream is, String httpContentType, boolean lenient)
Creates a Reader using an InputStream an the associated content-type header.
Method Summary
StringcalculateHttpEncoding(String cTMime, String cTEnc, String bomEnc, String xmlGuessEnc, String xmlEnc, InputStream is, boolean lenient)
StringcalculateRawEncoding(String bomEnc, String xmlGuessEnc, String xmlEnc, InputStream is)
voidclose()
Closes the XmlReader stream.
voiddoHttpStream(InputStream is, String httpContentType, boolean lenient)
voiddoLenientDetection(String httpContentType, XmlStreamReaderException ex)
voiddoRawStream(InputStream is, boolean lenient)
static StringgetBOMEncoding(BufferedInputStream is)
static StringgetContentTypeEncoding(String httpContentType)
static StringgetContentTypeMime(String httpContentType)
static StringgetDefaultEncoding()
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.
StringgetEncoding()
Returns the charset encoding of the XmlReader.
static StringgetXmlProlog(BufferedInputStream is, String guessedEnc)
static StringgetXMLGuessEncoding(BufferedInputStream is)
static booleanisAppXml(String mime)
static booleanisTextXml(String mime)
voidprepareReader(InputStream is, String encoding)
intread(char[] buf, int offset, int len)
static voidsetDefaultEncoding(String encoding)
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.

Field Detail

BUFFER_SIZE

private static final int BUFFER_SIZE

CHARSET_PATTERN

private static final Pattern CHARSET_PATTERN

EBCDIC

private static final String EBCDIC

ENCODING_PATTERN

static final Pattern ENCODING_PATTERN

HTTP_EX_1

private static final MessageFormat HTTP_EX_1

HTTP_EX_2

private static final MessageFormat HTTP_EX_2

HTTP_EX_3

private static final MessageFormat HTTP_EX_3

RAW_EX_1

private static final MessageFormat RAW_EX_1

RAW_EX_2

private static final MessageFormat RAW_EX_2

US_ASCII

private static final String US_ASCII

UTF_16

private static final String UTF_16

UTF_16BE

private static final String UTF_16BE

UTF_16LE

private static final String UTF_16LE

UTF_8

private static final String UTF_8

_defaultEncoding

private String _defaultEncoding

_encoding

private String _encoding

_reader

private Reader _reader

_staticDefaultEncoding

private static String _staticDefaultEncoding

Constructor Detail

XmlReader

public XmlReader(File file)
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.

Parameters: file File to create a Reader from.

Throws: IOException thrown if there is a problem reading the file.

XmlReader

public XmlReader(InputStream is)
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.

Parameters: is InputStream to create a Reader from.

Throws: IOException thrown if there is a problem reading the stream.

XmlReader

public XmlReader(InputStream is, boolean lenient)
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.

Parameters: is InputStream to create a Reader from. lenient indicates if the charset encoding detection should be relaxed.

Throws: IOException thrown if there is a problem reading the stream. XmlStreamReaderException thrown if the charset encoding could not be determined according to the specs.

XmlReader

public XmlReader(URL url)
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.

Parameters: url URL to create a Reader from.

Throws: IOException thrown if there is a problem reading the stream of the URL.

XmlReader

public XmlReader(URLConnection conn)
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.

Parameters: conn URLConnection to create a Reader from.

Throws: IOException thrown if there is a problem reading the stream of the URLConnection.

XmlReader

public XmlReader(InputStream is, String httpContentType)
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.

Parameters: 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.

XmlReader

public XmlReader(InputStream is, String httpContentType, boolean lenient, String defaultEncoding)
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.

Parameters: 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: IOException thrown if there is a problem reading the file. XmlStreamReaderException thrown if the charset encoding could not be determined according to the specs.

XmlReader

public XmlReader(InputStream is, String httpContentType, boolean lenient)
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.

Parameters: 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: IOException thrown if there is a problem reading the file. XmlStreamReaderException thrown if the charset encoding could not be determined according to the specs.

Method Detail

calculateHttpEncoding

private String calculateHttpEncoding(String cTMime, String cTEnc, String bomEnc, String xmlGuessEnc, String xmlEnc, InputStream is, boolean lenient)

calculateRawEncoding

private String calculateRawEncoding(String bomEnc, String xmlGuessEnc, String xmlEnc, InputStream is)

close

public void close()
Closes the XmlReader stream.

Throws: IOException thrown if there was a problem closing the stream.

doHttpStream

private void doHttpStream(InputStream is, String httpContentType, boolean lenient)

doLenientDetection

private void doLenientDetection(String httpContentType, XmlStreamReaderException ex)

doRawStream

private void doRawStream(InputStream is, boolean lenient)

getBOMEncoding

private static String getBOMEncoding(BufferedInputStream is)

getContentTypeEncoding

private static String getContentTypeEncoding(String httpContentType)

getContentTypeMime

private static String getContentTypeMime(String httpContentType)

getDefaultEncoding

public static String getDefaultEncoding()
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.

getEncoding

public String getEncoding()
Returns the charset encoding of the XmlReader.

Returns: charset encoding.

getXmlProlog

private static String getXmlProlog(BufferedInputStream is, String guessedEnc)

getXMLGuessEncoding

private static String getXMLGuessEncoding(BufferedInputStream is)

isAppXml

private static boolean isAppXml(String mime)

isTextXml

private static boolean isTextXml(String mime)

prepareReader

private void prepareReader(InputStream is, String encoding)

read

public int read(char[] buf, int offset, int len)

setDefaultEncoding

public static void setDefaultEncoding(String encoding)
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.

Parameters: encoding charset encoding to default to.