http://codehaus-plexus.github.io/plexus-utils/: A collection of various utility classes to ease working with strings, files, command lines, XML and more. (Codehaus Plexus)
  • Jason van Zyl
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/*
 * 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.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;


Character stream that handles (or at least attempts 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)
Since:1.4.4
/**
 * Character stream that handles (or at least attempts to) all the necessary Voodo to figure out the charset encoding of
 * the XML document within the stream.
 * <p>
 * IMPORTANT: This class is not related in any way to the org.xml.sax.XMLReader. This one IS a character stream.
 * <p>
 * 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).
 * <p>
 * The XmlReader class handles the charset encoding of XML documents in Files, raw streams and HTTP streams by offering
 * a wide set of constructors.
 * <P>
 * 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,
 * <a href="http://diveintomark.org/archives/2004/02/13/xml-media-types"> Determining the character encoding of a
 * feed</a>.
 * <p>
 * 
 * @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)
 * @since 1.4.4
 */
public class XmlStreamReader
    extends XmlReader
{
    
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.



Params:
  • file – File to create a Reader from.
Throws:
  • IOException – thrown if there is a problem reading the file.
/**
     * Creates a Reader for a File.
     * <p>
     * It looks for the UTF-8 BOM first, if none sniffs the XML prolog charset, if this is also missing defaults to
     * UTF-8.
     * <p>
     * It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
     * <p>
     * 
     * @param file File to create a Reader from.
     * @throws IOException thrown if there is a problem reading the file.
     */
    public XmlStreamReader( File file )
        throws IOException
    {
        super( 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.



Params:
  • is – InputStream to create a Reader from.
Throws:
  • IOException – thrown if there is a problem reading the stream.
/**
     * Creates a Reader for a raw InputStream.
     * <p>
     * It follows the same logic used for files.
     * <p>
     * It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
     * <p>
     * 
     * @param is InputStream to create a Reader from.
     * @throws IOException thrown if there is a problem reading the stream.
     */
    public XmlStreamReader( InputStream is )
        throws IOException
    {
        super( is );
    }

    
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.



Params:
  • is – InputStream to create a Reader from.
  • lenient – indicates if the charset encoding detection should be relaxed.
Throws:
/**
     * Creates a Reader for a raw InputStream.
     * <p>
     * It follows the same logic used for files.
     * <p>
     * If lenient detection is indicated and the detection above fails as per specifications it then attempts the
     * following:
     * <p>
     * If the content type was 'text/html' it replaces it with 'text/xml' and tries the detection again.
     * <p>
     * Else if the XML prolog had a charset encoding that encoding is used.
     * <p>
     * Else if the content type had a charset encoding that encoding is used.
     * <p>
     * Else 'UTF-8' is used.
     * <p>
     * If lenient detection is indicated an XmlStreamReaderException is never thrown.
     * <p>
     * 
     * @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 XmlStreamReader( InputStream is, boolean lenient )
        throws IOException, XmlStreamReaderException
    {
        super( is, lenient );
    }

    
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.



Params:
  • url – URL to create a Reader from.
Throws:
  • IOException – thrown if there is a problem reading the stream of the URL.
/**
     * Creates a Reader using the InputStream of a URL.
     * <p>
     * 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.
     * <p>
     * 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.
     * <p>
     * It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
     * <p>
     * 
     * @param url URL to create a Reader from.
     * @throws IOException thrown if there is a problem reading the stream of the URL.
     */
    public XmlStreamReader( URL url )
        throws IOException
    {
        super( url );
    }

    
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.



Params:
  • conn – URLConnection to create a Reader from.
Throws:
  • IOException – thrown if there is a problem reading the stream of the URLConnection.
/**
     * Creates a Reader using the InputStream of a URLConnection.
     * <p>
     * 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.
     * <p>
     * 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.
     * <p>
     * It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
     * <p>
     * 
     * @param conn URLConnection to create a Reader from.
     * @throws IOException thrown if there is a problem reading the stream of the URLConnection.
     */
    public XmlStreamReader( URLConnection conn )
        throws IOException
    {
        super( conn );
    }

    
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.



Params:
  • 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.
/**
     * Creates a Reader using an InputStream an the associated content-type header.
     * <p>
     * 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.
     * <p>
     * It does a lenient charset encoding detection, check the constructor with the lenient parameter for details.
     * <p>
     * 
     * @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 XmlStreamReader( InputStream is, String httpContentType )
        throws IOException
    {
        super( is, httpContentType );
    }

    
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.



Params:
  • 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:
/**
     * Creates a Reader using an InputStream an the associated content-type header. This constructor is lenient
     * regarding the encoding detection.
     * <p>
     * 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.
     * <p>
     * If lenient detection is indicated and the detection above fails as per specifications it then attempts the
     * following:
     * <p>
     * If the content type was 'text/html' it replaces it with 'text/xml' and tries the detection again.
     * <p>
     * Else if the XML prolog had a charset encoding that encoding is used.
     * <p>
     * Else if the content type had a charset encoding that encoding is used.
     * <p>
     * Else 'UTF-8' is used.
     * <p>
     * If lenient detection is indicated an XmlStreamReaderException is never thrown.
     * <p>
     * 
     * @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 XmlStreamReader( InputStream is, String httpContentType, boolean lenient, String defaultEncoding )
        throws IOException, XmlStreamReaderException
    {
        super( is, httpContentType, lenient, 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.



Params:
  • 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:
/**
     * Creates a Reader using an InputStream an the associated content-type header. This constructor is lenient
     * regarding the encoding detection.
     * <p>
     * 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.
     * <p>
     * If lenient detection is indicated and the detection above fails as per specifications it then attempts the
     * following:
     * <p>
     * If the content type was 'text/html' it replaces it with 'text/xml' and tries the detection again.
     * <p>
     * Else if the XML prolog had a charset encoding that encoding is used.
     * <p>
     * Else if the content type had a charset encoding that encoding is used.
     * <p>
     * Else 'UTF-8' is used.
     * <p>
     * If lenient detection is indicated an XmlStreamReaderException is never thrown.
     * <p>
     * 
     * @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 XmlStreamReader( InputStream is, String httpContentType, boolean lenient )
        throws IOException, XmlStreamReaderException
    {
        super( is, httpContentType, lenient );
    }
}