Re: [xml-dev] How to open XML file that reference entity resolver (DTD)

[Andrew Welch <andrew.j.welch@gmail.com>]

The entity resolver I wrote for Kernow is here:

http://kernowforsaxon.svn.sourceforge.net/viewvc/kernowforsaxon/kernow/trunk/src/net/sf/kernow/transform/CustomEntityResolver.java?revision=256&view=markup

That will check a local directory first, then the store in memory,
falling back to getting the doc itself.

To use it:

xmlReader.setEntityResolver(CustomerEntityResolver.getInstance())

cheers
andrew


On 30 June 2010 15:23, Jack Bush <netbeansfan@yahoo.com.au> wrote:
> Hi Liam,
>
> I took up your 3rd suggestion by overriding the default entity resolver by creating LocalDTDResolver.java as follows:
>
>     public class LocalDTDResolver implements EntityResolver {
>         String mySystemIdToIntercept;
>         File myLocalDtdPath;
>         URL localDtdFileAsUrl;
>         public LocalDTDResolver( String systemIdToIntercept, File localDtdPath ) throws MalformedURLException {
>             mySystemIdToIntercept = systemIdToIntercept;
>             myLocalDtdPath = localDtdPath;
>             localDtdFileAsUrl = myLocalDtdPath.toURI().toURL();
>         }
>         public InputSource resolveEntity (String publicId, String systemId) {
>             if (systemId.equals( mySystemIdToIntercept )) {
>                 return new InputSource( localDtdFileAsUrl.toString() );
>             }
>             else {
>                 // use the default behaviour (?)
>                 return null;
>             }
>         }
>     }
> MyApplication.java
>     .....
>     LocalDTDResolver localDTDResolver =
>     new LocalDTDResolver("http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd";,
>     new File("E:\\Tmp\\xhtml1-transitional.dtd")); // Place xhtml1-transitional.dtd in E:\
>     SAXBuilder saxBuilder = new SAXBuilder(false);
>     saxBuilder.setEntityResolver(localDTDResolver);
>     cityJDOMDocument = saxBuilder.build(new BufferedReader(new FileReader("C:\City.xml")));
>     ......
>
> However, it appears that the LocalDTDResolver class is partly working by generating the following different error:
>
> java.io.FileNotFoundException: E:\Tmp\xhtml-lat1.ent (The system cannot find the file specified)
> at java.io.FileInputStream.open(Native Method)
> at java.io.FileInputStream.<init>(FileInputStream.java:106)
> at java.io.FileInputStream.<init>(FileInputStream.java:66)
> at sun.net.www.protocol.file.FileURLConnection.connect(FileURLConnection.java:70)
> at sun.net.www.protocol.file.FileURLConnection.getInputStream(FileURLConnection.java:161)
> at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.setupCurrentEntity(XMLEntityManager.java:653)
> at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.startEntity(XMLEntityManager.java:1315)
> at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.startEntity(XMLEntityManager.java:1252)
> at com.sun.org.apache.xerces.internal.impl.XMLDTDScannerImpl.startPE(XMLDTDScannerImpl.java:722)
> at com.sun.org.apache.xerces.internal.impl.XMLDTDScannerImpl.skipSeparator(XMLDTDScannerImpl.java:2068)
> at com.sun.org.apache.xerces.internal.impl.XMLDTDScannerImpl.scanDecls(XMLDTDScannerImpl.java:2031)
> at com.sun.org.apache.xerces.internal.impl.XMLDTDScannerImpl.scanDTDExternalSubset(XMLDTDScannerImpl.java:320)
> at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.dispatch(XMLDocumentScannerImpl.java:1202)
> at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.next(XMLDocumentScannerImpl.java:1090)
> at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:1003)
> at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:648)
> at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:140)
> at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510)
> at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:807)
> at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737)
> at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:107)
> at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1205)
> at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:522)
> at org.jdom.input.SAXBuilder.build(SAXBuilder.java:489)
> at org.jdom.input.SAXBuilder.build(SAXBuilder.java:888)
>
> Do I need to put xhtml-lat1.ent (where from?) to E:\Tmp as well? And how to include it in LocalDTDResolver class as well?
>
> Btw, is Apache xml-commons-resolver-1.2 needed to be included in the CLASSPATH for this solution to work?
> Thanks again,
> Jack
>
> ----- Original Message ----
> From: Liam R E Quin <liam@w3.org>
> To: Jack Bush <netbeansfan@yahoo.com.au>
> Cc: xml-dev@lists.xml.org
> Sent: Tue, 29 June, 2010 11:36:44 PM
> Subject: Re: [xml-dev] How to open XML file that reference entity resolver (DTD)
>
> On Tue, 2010-06-29 at 01:00 -0700, Jack Bush wrote:
> [...]
>
>> Looks like it is the default Sax parser possibly via JAXP that does
>> not come with the XHTML DTDs and with an XML catalog set up to use
>> them instead of going to www.w3.org each time.
>> I am still waying through the references to use XML Catalog but it
>> doesn't appears to provide every facets to a Java solution. It would
>> great if you could provide some example of how everything are
>> interconnected together.
>
> When the XML parser sees it needs to fetch an external entity such as
> the document type definition, it gets a SYSTEM identifier, and often (as
> in this case) a PUBLIC identifier too.
>
> There is a piece of code that maps the (PUBLIC, SYSTEM) pair into a data
> stream. This code is usually called the entity resolver.
>
> The default entity resolver will look up the SYSTEM and PUBLIC
> identifiers in an external file, an XML Catalog, to see if they map
> to a pre-configured local copy.
>
> If not, the default entity resolver will treat the SYSTEM identifier as
> a URI (relative to the actual document in which it occurred, just like a
> link in an HTML document) and try to fetch it.
>
> So you have several choices to avoid network access:
> (1) add entries to the system XML Catalog
> (2) add your own XML Catalog file
> (3) override the default entity resolver
> (4) edit the document.
>
>> The 3rd option you have suggested by turning off validation with
>> SAXBuilder.setValidating(false) does not prevent the process of
>> resolving DTD document.
> OK. Others have said that too, although I've seen it work -- you do
> probably want the DTD loaded, though, with XHTML, so that entities work.
>
> There are plenty of examples of options 1 to 3 floating around, using
> Java.
>
> Liam
>
> --
> Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
> Pictures from old books: http://fromoldbooks.org/
> Ankh: irc.sorcery.net irc.gnome.org www.advogato.org
>
>
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-- 
Andrew Welch
http://andrewjwelch.com
Kernow: http://kernowforsaxon.sf.net/