Chapter 4 XML Processing

181

return source;

}

return null;

}

// Maps an external entity URI or Public Identifier to a

// physical location.

public String mapEntityURI(String entityURI) {

return entityCatalog.getProperty(entityURI);

}

public InputSource resolveEntity(String entityURI,

String entityURL) {

InputSource source = null;

try {

// Try first to map its URI/PublicId using the catalog.

if (entityURI != null) {

String mappedLocation = mapEntityURI(entityURI);

if (mappedLocation != null) {

source = openLocation(mappedLocation);

if (source != null) { return source; }

}

}

// Try then to access the entity using its URL/System Id.

if (entityURL != null) {

source = openLocation(entityURL);

if (source != null) { return source; }

}

}

} catch (Exception exception) { ... }

return null; // Let the default entity resolver handle it.

}

}

Code Example 4.11

Entity Resolver Using a Simple Entity Catalog

# DTD Public Indentifier to physical location (URL or resource path)

 //Sun Microsystems, Inc.  

J2EE Blueprints Group//DTD LineItem 1.0//EN: /com/sun/j2ee/blue 

prints/xmldocuments/rsrc/schemas/LineItem.dtd