org.enhydra.apache.xerces.readers
Class XCatalog

java.lang.Object
  |
  +--org.enhydra.apache.xerces.readers.XMLCatalogHandler
        |
        +--org.enhydra.apache.xerces.readers.XCatalog
All Implemented Interfaces:
EntityResolver

public class XCatalog
extends XMLCatalogHandler

This catalog supports the XCatalog proposal draft 0.2 posted to the xml-dev mailing list by John Cowan. XCatalog is an XML representation of the SGML Open TR9401:1997 catalog format. The current proposal supports public identifier maps, system identifier aliases, and public identifier prefix delegates. Refer to the XCatalog DTD for the full specification of this catalog format at http://www.ccil.org/~cowan/XML/XCatalog.html.

In order to use XCatalogs, you must write the catalog files with the following restrictions:

To use this catalog in a parser, set an XCatalog instance as the parser's EntityResolver. For example:

   XMLParser parser  = new AnyParser();
   Catalog   catalog = new XCatalog();
   parser.getEntityHandler().setEntityResolver(catalog);
 

Once installed, catalog files that conform to the XCatalog grammar can be appended to the catalog by calling the loadCatalog method on the parser or the catalog instance. The following example loads the contents of two catalog files:

   parser.loadCatalog(new InputSource("catalogs/cat1.xml"));
   parser.loadCatalog(new InputSource("http://host/catalogs/cat2.xml"));
 

Limitations: The following are the current limitations of this XCatalog implementation:

Version:
$Id: XCatalog.java,v 1.2 2005/01/26 08:28:44 jkjome Exp $
Author:
Andy Clark, IBM

Inner Class Summary
(package private)  class XCatalog.Parser
          Parser for XCatalog document instances.
 
Field Summary
(package private) static String BASE
          Base element name ("Base").
(package private) static String DELEGATE
          Delegate element name ("Delegate").
(package private) static String DTD
          XCatalog DTD resource name ("xcatalog.dtd").
(package private) static String EXTEND
          Extend element name ("Extend").
(package private) static String HREF
          HRef attribute name ("HRef").
(package private) static String MAP
          Map element name ("Map").
(package private) static String PUBLICID
          PublicID attribute name ("PublicID").
(package private) static String REMAP
          Remap element name ("Remap").
(package private) static String SYSTEMID
          SystemID attribute name ("SystemID").
(package private) static String XCATALOG
          XCatalog element name ("XCatalog").
static String XCATALOG_DTD_PUBLICID
          XCatalog public identifier string ("-//DTD XCatalog//EN").
 
Constructor Summary
XCatalog()
          Constructs an XCatalog instance.
 
Method Summary
 void addDelegateCatalog(String prefix, XCatalog catalog)
          Adds a delegate mapping.
 XCatalog getDelegateCatalog(String prefix)
          Returns the catalog for the given delegate prefix.
 Enumeration getDelegateCatalogKeys()
          Returns an enumeration of delegate prefixes.
(package private)  boolean isURL(String str)
          Returns true if the string is a valid URL.
 void loadCatalog(InputSource source)
          Loads the catalog stream specified by the given input source and appends the contents to the catalog.
 void removeDelegateCatalog(String prefix)
          Removes a delegate.
 InputSource resolveEntity(String publicId, String systemId)
          Resolves external entities.
 
Methods inherited from class org.enhydra.apache.xerces.readers.XMLCatalogHandler
addPublicMapping, addSystemMapping, getPublicMapping, getPublicMappingKeys, getSystemMapping, getSystemMappingKeys, removePublicMapping, removeSystemMapping
 
Methods inherited from class java.lang.Object
, clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

XCATALOG_DTD_PUBLICID

public static final String XCATALOG_DTD_PUBLICID
XCatalog public identifier string ("-//DTD XCatalog//EN").

DTD

static final String DTD
XCatalog DTD resource name ("xcatalog.dtd").

XCATALOG

static final String XCATALOG
XCatalog element name ("XCatalog").

MAP

static final String MAP
Map element name ("Map").

PUBLICID

static final String PUBLICID
PublicID attribute name ("PublicID").

HREF

static final String HREF
HRef attribute name ("HRef").

DELEGATE

static final String DELEGATE
Delegate element name ("Delegate").

EXTEND

static final String EXTEND
Extend element name ("Extend").

BASE

static final String BASE
Base element name ("Base").

REMAP

static final String REMAP
Remap element name ("Remap").

SYSTEMID

static final String SYSTEMID
SystemID attribute name ("SystemID").
Constructor Detail

XCatalog

public XCatalog()
Constructs an XCatalog instance.
Method Detail

loadCatalog

public void loadCatalog(InputSource source)
                 throws SAXException,
                        IOException
Loads the catalog stream specified by the given input source and appends the contents to the catalog.
Overrides:
loadCatalog in class XMLCatalogHandler
Parameters:
source - The catalog source.
Throws:
SAXException - Throws exception on SAX error.
IOException - Throws exception on i/o error.

resolveEntity

public InputSource resolveEntity(String publicId,
                                 String systemId)
                          throws SAXException,
                                 IOException
Resolves external entities.
Overrides:
resolveEntity in class XMLCatalogHandler
Parameters:
publicId - The public identifier used for entity resolution.
systemId - If the publicId is not null, this systemId is to be considered the default system identifier; else a system identifier alias mapping is requested.
Returns:
Returns the input source of the resolved entity or null if no resolution is possible.
Throws:
SAXException - Exception thrown on SAX error.
IOException - Exception thrown on i/o error.

addDelegateCatalog

public void addDelegateCatalog(String prefix,
                               XCatalog catalog)
Adds a delegate mapping. If the prefix of a public identifier matches a delegate prefix, then the delegate catalog is searched in order to resolve the identifier.

This method makes sure that prefixes that match each other are inserted into the delegate list in order of longest prefix length first.

Parameters:
prefix - The delegate prefix.
catalog - The delegate catalog.

removeDelegateCatalog

public void removeDelegateCatalog(String prefix)
Removes a delegate.
Parameters:
prefix - The delegate prefix to remove.

getDelegateCatalogKeys

public Enumeration getDelegateCatalogKeys()
Returns an enumeration of delegate prefixes.

getDelegateCatalog

public XCatalog getDelegateCatalog(String prefix)
Returns the catalog for the given delegate prefix.

isURL

boolean isURL(String str)
Returns true if the string is a valid URL.


Copyright © 1999 The Apache Software Foundation. All Rights reserved.