org.apache.xerces.readers
Class XCatalog

java.lang.Object
  |
  +--org.apache.xerces.readers.XMLCatalogHandler
        |
        +--org.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:

• You must follow the XCatalog grammar.
• You must specify the <!DOCTYPE> line with the PUBLIC specified as "-//DTD XCatalog//EN" or make sure that the system identifier is able to locate the XCatalog 0.2 DTD (which is included in the Jar file containing the org.apache.xerces.readers.XCatalog class). For example:

     <!DOCTYPE XCatalog PUBLIC "-//DTD XCatalog//EN" "org/apache/xerces/readers/xcatalog.dtd">
     

• The enclosing <XCatalog> document root element is not optional -- it must be specified.
• The Version attribute of the <XCatalog> has been modified from '#FIXED "1.0"' to '(0.1|0.2) "0.2"'.

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:

• No error checking is done to avoid circular Delegate or Extend references. Do not specify a combination of catalog files that reference each other.

Version:

$Id: XCatalog.java 315404 2000-04-04 21:14:25Z andyc $

Author:

Andy Clark, IBM

Field Summary

static java.lang.String

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

Constructor Summary

XCatalog()
Constructs an XCatalog instance.

Method Summary

void	addDelegateCatalog(java.lang.String prefix, XCatalog catalog) Adds a delegate mapping.
XCatalog	getDelegateCatalog(java.lang.String prefix) Returns the catalog for the given delegate prefix.
java.util.Enumeration	getDelegateCatalogKeys() Returns an enumeration of delegate prefixes.
void	loadCatalog(InputSource source) Loads the catalog stream specified by the given input source and appends the contents to the catalog.
void	removeDelegateCatalog(java.lang.String prefix) Removes a delegate.
InputSource	resolveEntity(java.lang.String publicId, java.lang.String systemId) Resolves external entities.

Methods inherited from class org.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 java.lang.String XCATALOG_DTD_PUBLICID

XCatalog public identifier string ("-//DTD XCatalog//EN").

Constructor Detail

XCatalog

public XCatalog()

Constructs an XCatalog instance.

Method Detail

loadCatalog

public void loadCatalog(InputSource source)
                 throws SAXException,
                        java.io.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.

java.io.IOException - Throws exception on i/o error.

resolveEntity

public InputSource resolveEntity(java.lang.String publicId,
                                 java.lang.String systemId)
                          throws SAXException,
                                 java.io.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.

java.io.IOException - Exception thrown on i/o error.

addDelegateCatalog

public void addDelegateCatalog(java.lang.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(java.lang.String prefix)

Removes a delegate.

Parameters:

prefix - The delegate prefix to remove.

getDelegateCatalogKeys

public java.util.Enumeration getDelegateCatalogKeys()

Returns an enumeration of delegate prefixes.

getDelegateCatalog

public XCatalog getDelegateCatalog(java.lang.String prefix)

Returns the catalog for the given delegate prefix.