Class XmlStreamReader
- java.lang.Object
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- java.io.Reader
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- org.apache.commons.io.input.XmlStreamReader
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
,java.lang.Readable
public class XmlStreamReader extends java.io.Reader
Character stream that handles all the necessary Voodoo 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, XmlStreamReader handles it and things work in all parsers).
The XmlStreamReader 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 a 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.
To build an instance, see
XmlStreamReader.Builder
.Originally developed for ROME under Apache License 2.0.
- Since:
- 2.0
- See Also:
XmlStreamWriter
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
XmlStreamReader.Builder
Builds a newXmlStreamWriter
instance.
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Field Summary
Fields Modifier and Type Field Description private static ByteOrderMark[]
BOMS
private static java.util.regex.Pattern
CHARSET_PATTERN
private java.lang.String
defaultEncoding
private static java.lang.String
EBCDIC
private java.lang.String
encoding
static java.util.regex.Pattern
ENCODING_PATTERN
Pattern capturing the encoding of the "xml" processing instruction.private static java.lang.String
HTTP_EX_1
private static java.lang.String
HTTP_EX_2
private static java.lang.String
HTTP_EX_3
private static java.lang.String
RAW_EX_1
private static java.lang.String
RAW_EX_2
private java.io.Reader
reader
private static java.lang.String
US_ASCII
private static java.lang.String
UTF_16
private static java.lang.String
UTF_16BE
private static java.lang.String
UTF_16LE
private static java.lang.String
UTF_32
private static java.lang.String
UTF_32BE
private static java.lang.String
UTF_32LE
private static java.lang.String
UTF_8
private static ByteOrderMark[]
XML_GUESS_BYTES
UTF_16LE and UTF_32LE have the same two starting BOM bytes.
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Constructor Summary
Constructors Constructor Description XmlStreamReader(java.io.File file)
Deprecated.XmlStreamReader(java.io.InputStream inputStream)
Deprecated.XmlStreamReader(java.io.InputStream inputStream, boolean lenient)
Deprecated.XmlStreamReader(java.io.InputStream inputStream, boolean lenient, java.lang.String defaultEncoding)
Deprecated.XmlStreamReader(java.io.InputStream inputStream, java.lang.String httpContentType)
Deprecated.XmlStreamReader(java.io.InputStream inputStream, java.lang.String httpContentType, boolean lenient)
Deprecated.XmlStreamReader(java.io.InputStream inputStream, java.lang.String httpContentType, boolean lenient, java.lang.String defaultEncoding)
Deprecated.XmlStreamReader(java.net.URL url)
Constructs a Reader using the InputStream of a URL.XmlStreamReader(java.net.URLConnection urlConnection, java.lang.String defaultEncoding)
Constructs a Reader using the InputStream of a URLConnection.XmlStreamReader(java.nio.file.Path file)
Deprecated.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description static XmlStreamReader.Builder
builder()
Constructs a newXmlStreamReader.Builder
.(package private) java.lang.String
calculateHttpEncoding(java.lang.String httpContentType, java.lang.String bomEnc, java.lang.String xmlGuessEnc, java.lang.String xmlEnc, boolean lenient)
Calculates the HTTP encoding.(package private) java.lang.String
calculateRawEncoding(java.lang.String bomEnc, java.lang.String xmlGuessEnc, java.lang.String xmlEnc)
Calculate the raw encoding.void
close()
Closes the XmlStreamReader stream.private java.lang.String
doLenientDetection(java.lang.String httpContentType, XmlStreamReaderException ex)
Does lenient detection.private java.lang.String
doRawStream(BOMInputStream bom, BOMInputStream pis, boolean lenient)
Process the raw stream.(package private) static java.lang.String
getContentTypeEncoding(java.lang.String httpContentType)
Gets the charset parameter value, NULL if not present, NULL if httpContentType is NULL.(package private) static java.lang.String
getContentTypeMime(java.lang.String httpContentType)
Gets the MIME type or NULL if httpContentType is NULL.java.lang.String
getDefaultEncoding()
Gets 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.java.lang.String
getEncoding()
Gets the charset encoding of the XmlStreamReader.private static java.lang.String
getXmlProlog(java.io.InputStream inputStream, java.lang.String guessedEnc)
Gets the encoding declared in the , NULL if none.(package private) static boolean
isAppXml(java.lang.String mime)
Tests if the MIME type belongs to the APPLICATION XML family.(package private) static boolean
isTextXml(java.lang.String mime)
Tests if the MIME type belongs to the TEXT XML family.private java.lang.String
processHttpStream(BOMInputStream bomInput, BOMInputStream piInput, java.lang.String httpContentType, boolean lenient)
Processes an HTTP stream.int
read(char[] buf, int offset, int len)
Reads the underlying reader'sread(char[], int, int)
method.
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Field Detail
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UTF_8
private static final java.lang.String UTF_8
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US_ASCII
private static final java.lang.String US_ASCII
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UTF_16BE
private static final java.lang.String UTF_16BE
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UTF_16LE
private static final java.lang.String UTF_16LE
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UTF_32BE
private static final java.lang.String UTF_32BE
- See Also:
- Constant Field Values
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UTF_32LE
private static final java.lang.String UTF_32LE
- See Also:
- Constant Field Values
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UTF_16
private static final java.lang.String UTF_16
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UTF_32
private static final java.lang.String UTF_32
- See Also:
- Constant Field Values
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EBCDIC
private static final java.lang.String EBCDIC
- See Also:
- Constant Field Values
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BOMS
private static final ByteOrderMark[] BOMS
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XML_GUESS_BYTES
private static final ByteOrderMark[] XML_GUESS_BYTES
UTF_16LE and UTF_32LE have the same two starting BOM bytes.
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CHARSET_PATTERN
private static final java.util.regex.Pattern CHARSET_PATTERN
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ENCODING_PATTERN
public static final java.util.regex.Pattern ENCODING_PATTERN
Pattern capturing the encoding of the "xml" processing instruction.
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RAW_EX_1
private static final java.lang.String RAW_EX_1
- See Also:
- Constant Field Values
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RAW_EX_2
private static final java.lang.String RAW_EX_2
- See Also:
- Constant Field Values
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HTTP_EX_1
private static final java.lang.String HTTP_EX_1
- See Also:
- Constant Field Values
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HTTP_EX_2
private static final java.lang.String HTTP_EX_2
- See Also:
- Constant Field Values
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HTTP_EX_3
private static final java.lang.String HTTP_EX_3
- See Also:
- Constant Field Values
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reader
private final java.io.Reader reader
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encoding
private final java.lang.String encoding
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defaultEncoding
private final java.lang.String defaultEncoding
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Constructor Detail
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XmlStreamReader
@Deprecated public XmlStreamReader(java.io.File file) throws java.io.IOException
Deprecated.Constructs 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:
java.lang.NullPointerException
- if the input isnull
.java.io.IOException
- thrown if there is a problem reading the file.
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XmlStreamReader
@Deprecated public XmlStreamReader(java.io.InputStream inputStream) throws java.io.IOException
Deprecated.Constructs 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:
inputStream
- InputStream to create a Reader from.- Throws:
java.lang.NullPointerException
- if the input stream isnull
.java.io.IOException
- thrown if there is a problem reading the stream.
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XmlStreamReader
@Deprecated public XmlStreamReader(java.io.InputStream inputStream, boolean lenient) throws java.io.IOException
Deprecated.Constructs 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:
inputStream
- InputStream to create a Reader from.lenient
- indicates if the charset encoding detection should be relaxed.- Throws:
java.lang.NullPointerException
- if the input stream isnull
.java.io.IOException
- thrown if there is a problem reading the stream.XmlStreamReaderException
- thrown if the charset encoding could not be determined according to the specification.
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XmlStreamReader
@Deprecated public XmlStreamReader(java.io.InputStream inputStream, boolean lenient, java.lang.String defaultEncoding) throws java.io.IOException
Deprecated.Constructs 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:
inputStream
- InputStream to create a Reader from.lenient
- indicates if the charset encoding detection should be relaxed.defaultEncoding
- The default encoding- Throws:
java.lang.NullPointerException
- if the input stream isnull
.java.io.IOException
- thrown if there is a problem reading the stream.XmlStreamReaderException
- thrown if the charset encoding could not be determined according to the specification.
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XmlStreamReader
@Deprecated public XmlStreamReader(java.io.InputStream inputStream, java.lang.String httpContentType) throws java.io.IOException
Deprecated.Constructs a Reader using an InputStream and 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:
inputStream
- InputStream to create the reader from.httpContentType
- content-type header to use for the resolution of the charset encoding.- Throws:
java.lang.NullPointerException
- if the input stream isnull
.java.io.IOException
- thrown if there is a problem reading the file.
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XmlStreamReader
@Deprecated public XmlStreamReader(java.io.InputStream inputStream, java.lang.String httpContentType, boolean lenient) throws java.io.IOException
Deprecated.Constructs a Reader using an InputStream and 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:
inputStream
- 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:
java.lang.NullPointerException
- if the input stream isnull
.java.io.IOException
- thrown if there is a problem reading the file.XmlStreamReaderException
- thrown if the charset encoding could not be determined according to the specification.
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XmlStreamReader
@Deprecated public XmlStreamReader(java.io.InputStream inputStream, java.lang.String httpContentType, boolean lenient, java.lang.String defaultEncoding) throws java.io.IOException
Deprecated.Constructs a Reader using an InputStream and 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:
inputStream
- 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.defaultEncoding
- The default encoding- Throws:
java.lang.NullPointerException
- if the input stream isnull
.java.io.IOException
- thrown if there is a problem reading the file.XmlStreamReaderException
- thrown if the charset encoding could not be determined according to the specification.
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XmlStreamReader
@Deprecated public XmlStreamReader(java.nio.file.Path file) throws java.io.IOException
Deprecated.Constructs 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:
java.lang.NullPointerException
- if the input isnull
.java.io.IOException
- thrown if there is a problem reading the file.- Since:
- 2.11.0
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XmlStreamReader
public XmlStreamReader(java.net.URL url) throws java.io.IOException
Constructs 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:
java.lang.NullPointerException
- if the input isnull
.java.io.IOException
- thrown if there is a problem reading the stream of the URL.
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XmlStreamReader
public XmlStreamReader(java.net.URLConnection urlConnection, java.lang.String defaultEncoding) throws java.io.IOException
Constructs 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:
urlConnection
- URLConnection to create a Reader from.defaultEncoding
- The default encoding- Throws:
java.lang.NullPointerException
- if the input isnull
.java.io.IOException
- thrown if there is a problem reading the stream of the URLConnection.
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Method Detail
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builder
public static XmlStreamReader.Builder builder()
Constructs a newXmlStreamReader.Builder
.- Returns:
- a new
XmlStreamReader.Builder
. - Since:
- 2.12.0
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getContentTypeEncoding
static java.lang.String getContentTypeEncoding(java.lang.String httpContentType)
Gets the charset parameter value, NULL if not present, NULL if httpContentType is NULL.- Parameters:
httpContentType
- the HTTP content type- Returns:
- The content type encoding (upcased)
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getContentTypeMime
static java.lang.String getContentTypeMime(java.lang.String httpContentType)
Gets the MIME type or NULL if httpContentType is NULL.- Parameters:
httpContentType
- the HTTP content type- Returns:
- The mime content type
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getXmlProlog
private static java.lang.String getXmlProlog(java.io.InputStream inputStream, java.lang.String guessedEnc) throws java.io.IOException
Gets the encoding declared in the , NULL if none.- Parameters:
inputStream
- InputStream to create the reader from.guessedEnc
- guessed encoding- Returns:
- the encoding declared in the
- Throws:
java.io.IOException
- thrown if there is a problem reading the stream.
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isAppXml
static boolean isAppXml(java.lang.String mime)
Tests if the MIME type belongs to the APPLICATION XML family.- Parameters:
mime
- The mime type- Returns:
- true if the mime type belongs to the APPLICATION XML family, otherwise false
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isTextXml
static boolean isTextXml(java.lang.String mime)
Tests if the MIME type belongs to the TEXT XML family.- Parameters:
mime
- The mime type- Returns:
- true if the mime type belongs to the TEXT XML family, otherwise false
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calculateHttpEncoding
java.lang.String calculateHttpEncoding(java.lang.String httpContentType, java.lang.String bomEnc, java.lang.String xmlGuessEnc, java.lang.String xmlEnc, boolean lenient) throws java.io.IOException
Calculates the HTTP encoding.- Parameters:
httpContentType
- The HTTP content typebomEnc
- BOM encodingxmlGuessEnc
- XML Guess encodingxmlEnc
- XML encodinglenient
- indicates if the charset encoding detection should be relaxed.- Returns:
- the HTTP encoding
- Throws:
java.io.IOException
- thrown if there is a problem reading the stream.
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calculateRawEncoding
java.lang.String calculateRawEncoding(java.lang.String bomEnc, java.lang.String xmlGuessEnc, java.lang.String xmlEnc) throws java.io.IOException
Calculate the raw encoding.- Parameters:
bomEnc
- BOM encodingxmlGuessEnc
- XML Guess encodingxmlEnc
- XML encoding- Returns:
- the raw encoding
- Throws:
java.io.IOException
- thrown if there is a problem reading the stream.
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close
public void close() throws java.io.IOException
Closes the XmlStreamReader stream.- Specified by:
close
in interfacejava.lang.AutoCloseable
- Specified by:
close
in interfacejava.io.Closeable
- Specified by:
close
in classjava.io.Reader
- Throws:
java.io.IOException
- thrown if there was a problem closing the stream.
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doLenientDetection
private java.lang.String doLenientDetection(java.lang.String httpContentType, XmlStreamReaderException ex) throws java.io.IOException
Does lenient detection.- Parameters:
httpContentType
- content-type header to use for the resolution of the charset encoding.ex
- The thrown exception- Returns:
- the encoding
- Throws:
java.io.IOException
- thrown if there is a problem reading the stream.
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doRawStream
private java.lang.String doRawStream(BOMInputStream bom, BOMInputStream pis, boolean lenient) throws java.io.IOException
Process the raw stream.- Parameters:
bom
- BOMInputStream to detect byte order markspis
- BOMInputStream to guess XML encodinglenient
- indicates if the charset encoding detection should be relaxed.- Returns:
- the encoding to be used
- Throws:
java.io.IOException
- thrown if there is a problem reading the stream.
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getDefaultEncoding
public java.lang.String getDefaultEncoding()
Gets 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.
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getEncoding
public java.lang.String getEncoding()
Gets the charset encoding of the XmlStreamReader.- Returns:
- charset encoding.
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processHttpStream
private java.lang.String processHttpStream(BOMInputStream bomInput, BOMInputStream piInput, java.lang.String httpContentType, boolean lenient) throws java.io.IOException
Processes an HTTP stream.- Parameters:
bomInput
- BOMInputStream to detect byte order markspiInput
- BOMInputStream to guess XML encodinghttpContentType
- The HTTP content typelenient
- indicates if the charset encoding detection should be relaxed.- Returns:
- the encoding to be used
- Throws:
java.io.IOException
- thrown if there is a problem reading the stream.
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read
public int read(char[] buf, int offset, int len) throws java.io.IOException
Reads the underlying reader'sread(char[], int, int)
method.- Specified by:
read
in classjava.io.Reader
- Parameters:
buf
- the buffer to read the characters intooffset
- The start offsetlen
- The number of bytes to read- Returns:
- the number of characters read or -1 if the end of stream
- Throws:
java.io.IOException
- if an I/O error occurs.
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