import com.sun.org.apache.xerces.internal.xni.grammars.XMLDTDDescription; //导入依赖的package包/类
/**
 * <p>Locates an external subset for documents which do not explicitly
 * provide one. If no external subset is provided, this method should
 * return <code>null</code>.</p>
 *
 * @param grammarDescription a description of the DTD
 *
 * @throws XNIException Thrown on general error.
 * @throws IOException  Thrown if resolved entity stream cannot be
 *                      opened or some other i/o error occurs.
 */
public XMLInputSource getExternalSubset(XMLDTDDescription grammarDescription)
        throws XNIException, IOException {

    if (fEntityResolver != null) {

        String name = grammarDescription.getRootName();
        String baseURI = grammarDescription.getBaseSystemId();

        // Resolve using EntityResolver2
        try {
            InputSource inputSource = fEntityResolver.getExternalSubset(name, baseURI);
            return (inputSource != null) ? createXMLInputSource(inputSource, baseURI) : null;
        }
        // error resolving external subset
        catch (SAXException e) {
            Exception ex = e.getException();
            if (ex == null) {
                ex = e;
            }
            throw new XNIException(ex);
        }
    }

    // unable to resolve external subset
    return null;

}
 

import com.sun.org.apache.xerces.internal.xni.grammars.XMLDTDDescription; //导入依赖的package包/类
/**
 * Resolves an external parsed entity. If the entity cannot be
 * resolved, this method should return null.
 *
 * @param resourceIdentifier contains the physical co-ordinates of the resource to be resolved
 *
 * @throws XNIException Thrown on general error.
 * @throws IOException  Thrown if resolved entity stream cannot be
 *                      opened or some other i/o error occurs.
 */
public XMLInputSource resolveEntity(XMLResourceIdentifier resourceIdentifier)
        throws XNIException, IOException {

    if (fEntityResolver != null) {

        String pubId = resourceIdentifier.getPublicId();
        String sysId = resourceIdentifier.getLiteralSystemId();
        String baseURI = resourceIdentifier.getBaseSystemId();
        String name = null;
        if (resourceIdentifier instanceof XMLDTDDescription) {
            name = "[dtd]";
        }
        else if (resourceIdentifier instanceof XMLEntityDescription) {
            name = ((XMLEntityDescription) resourceIdentifier).getEntityName();
        }

        // When both pubId and sysId are null, the user's entity resolver
        // can do nothing about it. We'd better not bother calling it.
        // This happens when the resourceIdentifier is a GrammarDescription,
        // which describes a schema grammar of some namespace, but without
        // any schema location hint. -Sg
        if (pubId == null && sysId == null) {
            return null;
        }

        // Resolve using EntityResolver2
        try {
            InputSource inputSource =
                fEntityResolver.resolveEntity(name, pubId, baseURI, sysId);
            return (inputSource != null) ? createXMLInputSource(inputSource, baseURI) : null;
        }
        // error resolving entity
        catch (SAXException e) {
            Exception ex = e.getException();
            if (ex == null) {
                ex = e;
            }
            throw new XNIException(ex);
        }
    }

    // unable to resolve entity
    return null;

}
 

import com.sun.org.apache.xerces.internal.xni.grammars.XMLDTDDescription; //导入依赖的package包/类
/**
 * <p>Locates an external subset for documents which do not explicitly
 * provide one. If no external subset is provided, this method should
 * return <code>null</code>.</p>
 *
 * @param grammarDescription a description of the DTD
 *
 * @throws XNIException Thrown on general error.
 * @throws IOException  Thrown if resolved entity stream cannot be
 *                      opened or some other i/o error occurs.
 */
public XMLInputSource getExternalSubset(XMLDTDDescription grammarDescription)
    throws XNIException, IOException;