ImportUnmarshaller

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package org.exolab.castor.xml.schema.reader;

import org.exolab.castor.net.URIException;
import org.exolab.castor.net.URILocation;
import org.exolab.castor.net.URIResolver;
import org.exolab.castor.xml.AttributeSet;
import org.exolab.castor.xml.XMLException;
import org.exolab.castor.xml.schema.SchemaContext;
import org.exolab.castor.xml.schema.Schema;
import org.exolab.castor.xml.schema.SchemaException;
import org.exolab.castor.xml.schema.SchemaNames;
import org.xml.sax.InputSource;
import org.xml.sax.Locator;
import org.xml.sax.Parser;

public class ImportUnmarshaller extends ComponentReader
{


    public ImportUnmarshaller(
            final SchemaContext schemaContext,
            final Schema schema,
            final AttributeSet atts,
            final URIResolver uriResolver,
            final Locator locator,
            final SchemaUnmarshallerState state)
    throws XMLException {
        super(schemaContext);
        setURIResolver(uriResolver);

        URILocation uri = null;
        //-- Get schemaLocation
        String schemaLocation = atts.getValue(SchemaNames.SCHEMALOCATION_ATTR);
        //-- Get namespace
        String namespace = atts.getValue("namespace");

        if ((schemaLocation == null) && (namespace == null)) {
            //-- A legal <import/> element...just return
            return;
        }

        boolean hasLocation = (schemaLocation != null);
        if (hasLocation) {

            if (schemaLocation.indexOf("\\") != -1) {
                String err = "'" + schemaLocation +
                    "' is not a valid URI as defined by IETF RFC 2396.";
                err += "The URI mustn't contain '\\'.";
                throw new SchemaException(err);
            }

            if (namespace == null) namespace = "";

            try {
                String documentBase = locator.getSystemId();
                if (documentBase != null) {
                    if (!documentBase.endsWith("/"))
                        documentBase = documentBase.substring(0, documentBase.lastIndexOf('/') +1 );
                }
                uri = getURIResolver().resolve(schemaLocation, documentBase);
                if (uri != null) {
                    schemaLocation = uri.getAbsoluteURI();
                }
            }
            catch (URIException urix) {
                throw new XMLException(urix);
            }
        }
        else {
            schemaLocation = namespace;
            try {
                uri = getURIResolver().resolveURN(namespace);
            }
            catch (URIException urix) {
                throw new XMLException(urix);
            }
            if (uri == null) {
                String err = "Unable to resolve Schema corresponding " +
                    "to namespace '" + namespace + "'.";
                throw new SchemaException(err);

            }
        }

        //-- Make sure targetNamespace is not the same as the
        //-- importing schema, see section 4.2.3 in the
        //-- XML Schema Recommendation
        if (namespace.equals(schema.getTargetNamespace()) )
            throw new SchemaException("the 'namespace' attribute in the <import> element cannot be the same of the targetNamespace of the global schema");

        //-- Schema object to hold import schema
        boolean addSchema = false;
        Schema importedSchema = schema.getImportedSchema(namespace, true);

        //-- Have we already imported this XML Schema file?
        if (state.processed(schemaLocation)) {
           if (importedSchema == null)
               schema.addImportedSchema(state.getSchema(schemaLocation));
           return;
        }

        boolean alreadyLoaded = false;
        if (importedSchema == null) {
            if (uri instanceof SchemaLocation) {
                importedSchema = ((SchemaLocation)uri).getSchema();
                schema.addImportedSchema(importedSchema);
                alreadyLoaded = true;
            }
            else {
                importedSchema = new Schema();
                addSchema = true;
            }
        }
        else {
            // check schema location, if different, allow merge
            if (hasLocation) {
                String tmpLocation = importedSchema.getSchemaLocation();
                alreadyLoaded = schemaLocation.equals(tmpLocation) || importedSchema.includeProcessed(schemaLocation);
                //-- keep track of the original schemaLocation as an include
                if(! alreadyLoaded) {
                    importedSchema.addInclude(tmpLocation);
                }
            } else {
                //-- only namespace can be used, no way to distinguish
                //-- multiple imports...mark as alreadyLoaded
                //-- see W3C XML Schema 1.0 Recommendation (part 1)
                //-- section 4.2.3...
                //-- <quote>... Given that the schemaLocation [attribute] is only
                //--   a hint, it is open to applications to ignore all but the
                //--   first <import> for a given namespace, regardless of the
                //--   <em>actual value</em> of schemaLocation, but such a strategy
                //--   risks missing useful information when new schemaLocations
                //--  are offered.</quote>
                alreadyLoaded = true;
            }
        }

        state.markAsProcessed(schemaLocation, importedSchema);

        if (alreadyLoaded) return;

        //-- Parser Schema
        Parser parser = null;
        try {
            parser = getSchemaContext().getParser();
        }
        catch(RuntimeException rte) {}
        if (parser == null) {
            throw new SchemaException("Error failed to create parser for import");
        }
    //-- Create Schema object and setup unmarshaller
    SchemaUnmarshaller schemaUnmarshaller = new SchemaUnmarshaller(getSchemaContext(), state);
          schemaUnmarshaller.setURIResolver(getURIResolver());
    schemaUnmarshaller.setSchema(importedSchema);
    Sax2ComponentReader handler = new Sax2ComponentReader(schemaUnmarshaller);
    parser.setDocumentHandler(handler);
    parser.setErrorHandler(handler);

        try {
            InputSource source = new InputSource(uri.getReader());
            source.setSystemId(uri.getAbsoluteURI());
            parser.parse(source);
        }
        catch(java.io.IOException ioe) {
            throw new SchemaException("Error reading import file '"+schemaLocation+"': "+ ioe);
        }
        catch(org.xml.sax.SAXException sx) {
            throw new SchemaException(sx);
        }

        //-- Add schema to list of imported schemas (if not already present)
        if (addSchema)
        {
            importedSchema.setSchemaLocation(schemaLocation);
            schema.addImportedSchema(importedSchema);
        }
    }


    /**
     * Sets the name of the element that this UnknownUnmarshaller handles
    **/
    public String elementName() {
        return SchemaNames.IMPORT;
    } //-- elementName

    /**
     * Returns the Object created by this ComponentReader
     * @return the Object created by this ComponentReader
    **/
    public Object getObject() {
        return null;
    } //-- getObject

}