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

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
voidclose()
Closes the XmlReader stream.
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.
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.

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

close

public void close()
Closes the XmlReader stream.

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

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.

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.

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