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com.sun.syndication.io
Class XmlReader
java.lang.Objectjava.io.Reader
- public class XmlReader
- extends java.io.Reader
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.
| Field Summary | |
private java.lang.String |
_encoding
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private java.io.Reader |
_reader
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private static java.util.regex.Pattern |
CHARSET_PATTERN
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private static java.util.regex.Pattern |
ENCODING_PATTERN
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private static java.text.MessageFormat |
HTTP_EX_1
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private static java.text.MessageFormat |
HTTP_EX_2
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private static java.text.MessageFormat |
HTTP_EX_3
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private static int |
PUSHBACK_MAX_SIZE
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private static java.text.MessageFormat |
RAW_EX_1
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private static java.text.MessageFormat |
RAW_EX_2
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private static java.lang.String |
US_ASCII
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private static java.lang.String |
UTF_16
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private static java.lang.String |
UTF_16BE
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private static java.lang.String |
UTF_16LE
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private static java.lang.String |
UTF_8
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| Fields inherited from class java.io.Reader |
lock |
| Constructor Summary | |
XmlReader(java.io.File file)
Creates a Reader for a File. |
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XmlReader(java.io.InputStream is)
Creates a Reader for a raw InputStream. |
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XmlReader(java.io.InputStream is,
boolean lenient)
Creates a Reader for a raw InputStream. |
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XmlReader(java.io.InputStream is,
java.lang.String httpContentType)
Creates a Reader using an InputStream an the associated content-type header. |
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XmlReader(java.io.InputStream is,
java.lang.String httpContentType,
boolean lenient)
Creates a Reader using an InputStream an the associated content-type header. |
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XmlReader(java.net.URL url)
Creates a Reader using the InputStream of a URL. |
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XmlReader(java.net.URLConnection conn)
Creates a Reader using the InputStream of a URLConnection. |
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| Methods inherited from class java.io.Reader |
mark, markSupported, read, read, ready, reset, skip |
| Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Field Detail |
PUSHBACK_MAX_SIZE
private static final int PUSHBACK_MAX_SIZE
- See Also:
- Constant Field Values
UTF_8
private static final java.lang.String UTF_8
- See Also:
- Constant Field Values
US_ASCII
private static final java.lang.String US_ASCII
- See Also:
- Constant Field Values
UTF_16BE
private static final java.lang.String UTF_16BE
- See Also:
- Constant Field Values
UTF_16LE
private static final java.lang.String UTF_16LE
- See Also:
- Constant Field Values
UTF_16
private static final java.lang.String UTF_16
- See Also:
- Constant Field Values
_reader
private java.io.Reader _reader
_encoding
private java.lang.String _encoding
CHARSET_PATTERN
private static final java.util.regex.Pattern CHARSET_PATTERN
ENCODING_PATTERN
private static final java.util.regex.Pattern ENCODING_PATTERN
RAW_EX_1
private static final java.text.MessageFormat RAW_EX_1
RAW_EX_2
private static final java.text.MessageFormat RAW_EX_2
HTTP_EX_1
private static final java.text.MessageFormat HTTP_EX_1
HTTP_EX_2
private static final java.text.MessageFormat HTTP_EX_2
HTTP_EX_3
private static final java.text.MessageFormat HTTP_EX_3
| Constructor Detail |
XmlReader
public XmlReader(java.io.File file) throws java.io.IOException
- 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.
XmlReader
public XmlReader(java.io.InputStream is) throws java.io.IOException
- 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.
XmlReader
public XmlReader(java.io.InputStream is, boolean lenient) throws java.io.IOException, XmlReaderException
- 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 XmlReaderException is never thrown.
XmlReader
public XmlReader(java.net.URL url) throws java.io.IOException
- 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.
XmlReader
public XmlReader(java.net.URLConnection conn) throws java.io.IOException
- 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.
XmlReader
public XmlReader(java.io.InputStream is, java.lang.String httpContentType) throws java.io.IOException
- 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.
XmlReader
public XmlReader(java.io.InputStream is, java.lang.String httpContentType, boolean lenient) throws java.io.IOException, XmlReaderException
- 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 XmlReaderException is never thrown.
| Method Detail |
doLenientDetection
private void doLenientDetection(java.lang.String httpContentType, XmlReaderException ex) throws java.io.IOException
getEncoding
public java.lang.String getEncoding()
- Returns the charset encoding of the XmlReader.
read
public int read(char[] buf,
int offset,
int len)
throws java.io.IOException
- Description copied from class:
java.io.Reader - Read chars from a stream and stores them into a caller
supplied buffer. It starts storing the data at index
offsetinto the buffer and attempts to readlenchars. This method can return before reading the number of chars requested. The actual number of chars read is returned as an int. A -1 is returned to indicate the end of the stream.This method will block until some data can be read.
This method operates by calling the single char
read()method in a loop until the desired number of chars are read. The read loop stops short if the end of the stream is encountered or if an IOException is encountered on any read operation except the first. If the first attempt to read a chars fails, the IOException is allowed to propagate upward. And subsequent IOException is caught and treated identically to an end of stream condition. Subclasses can (and should if possible) override this method to provide a more efficient implementation.
close
public void close()
throws java.io.IOException
- Closes the XmlReader stream.
doRawStream
private void doRawStream(java.io.InputStream is, boolean lenient) throws java.io.IOException
doHttpStream
private void doHttpStream(java.io.InputStream is, java.lang.String httpContentType, boolean lenient) throws java.io.IOException
prepareReader
private void prepareReader(java.io.InputStream is, java.lang.String encoding) throws java.io.IOException
calculateRawEncoding
private static java.lang.String calculateRawEncoding(java.lang.String bomEnc, java.lang.String xmlGuessEnc, java.lang.String xmlEnc, java.io.InputStream is) throws java.io.IOException
calculateHttpEncoding
private static java.lang.String calculateHttpEncoding(java.lang.String cTMime, java.lang.String cTEnc, java.lang.String bomEnc, java.lang.String xmlGuessEnc, java.lang.String xmlEnc, java.io.InputStream is, boolean lenient) throws java.io.IOException
getContentTypeMime
private static java.lang.String getContentTypeMime(java.lang.String httpContentType)
getContentTypeEncoding
private static java.lang.String getContentTypeEncoding(java.lang.String httpContentType)
getBOMEncoding
private static java.lang.String getBOMEncoding(java.io.PushbackInputStream is) throws java.io.IOException
getXMLGuessEncoding
private static java.lang.String getXMLGuessEncoding(java.io.PushbackInputStream is) throws java.io.IOException
getXmlProlog
private static java.lang.String getXmlProlog(java.io.PushbackInputStream is, java.lang.String guessedEnc) throws java.io.IOException
isAppXml
private static boolean isAppXml(java.lang.String mime)
isTextXml
private static boolean isTextXml(java.lang.String mime)
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DETAIL: FIELD | CONSTR | METHOD | ||||||||