com.sun.syndication.io
Class XmlReader

java.lang.Object
  extended byjava.io.Reader
      extended bycom.sun.syndication.io.XmlReader

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 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.

There are also some convenience static methods to find out charset encodings following the rules defined by HTTP, MIME types and XML specifications. All this is nicely explained by Mark Pilgrim in his blog, Determining the character encoding of a feed.

Author:
Alejandro Abdelnur

Field Summary
 
Fields inherited from class java.io.Reader
lock
 
Constructor Summary
XmlReader(java.io.File file)
          Creates a Reader for a File.
XmlReader(java.io.InputStream is)
          Creates a Reader for a raw InputStream.
XmlReader(java.io.InputStream is, java.lang.String httpContentType)
          Creates a Reader using an InputStream an the associated content-type header.
XmlReader(java.net.URL url)
          Creates a Reader using the InputStream of a URL.
XmlReader(java.net.URLConnection conn)
          Creates a Reader using the InputStream of a URLConnection.
 
Method Summary
 void close()
          Closes the XmlReader stream.
 java.lang.String getEncoding()
          Returns the charset encoding of the XmlReader.
 int read(char[] buf, int offset, int len)
           
 
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
 

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.

Parameters:
file - File to create a Reader from.
Throws:
java.io.IOException - thrown if there is a problem reading the file.

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.

Parameters:
is - InputStream to create a Reader from.
Throws:
java.io.IOException - thrown if there is a problem reading the stream.

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.

Parameters:
url - URL to create a Reader from.
Throws:
java.io.IOException - thrown if there is a problem reading the stream of the URL.

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.

Parameters:
conn - URLConnection to create a Reader from.
Throws:
java.io.IOException - thrown if there is a problem reading the stream of the URLConnection.

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.

Parameters:
is - InputStream to create the reader from.
httpContentType - content-type header to use for the resolution of the charset encoding.
Throws:
java.io.IOException - thrown if there is a problem reading the file.
Method Detail

getEncoding

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

Returns:
charset encoding.

read

public int read(char[] buf,
                int offset,
                int len)
         throws java.io.IOException
Throws:
java.io.IOException

close

public void close()
           throws java.io.IOException
Closes the XmlReader stream.

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


Copyright © 2004 Sun Microsystems. All Rights Reserved.