xmlpackagereader.java

jboss规则引擎

package org.drools.xml;

/*
 * Copyright 2005 JBoss Inc
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.net.URL;
import java.text.MessageFormat;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.ListIterator;
import java.util.Map;
import java.util.Set;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.drools.lang.descr.PackageDescr;
import org.drools.lang.descr.RuleDescr;
import org.xml.sax.Attributes;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.SAXNotRecognizedException;
import org.xml.sax.SAXParseException;
import org.xml.sax.helpers.DefaultHandler;

/**
 * <code>RuleSet</code> loader.
 *
 * Note you can override the default entity resolver by setting the System property of:
 *  <code>org.drools.io.EntityResolve</code> to your own custom entity resolver.
 *  This can be done using -Dorg.drools.io.EntityResolver=YourClassHere on the command line, for instance.
 *
 * @author <a href="mailto:[e-mail]">bob mcwhirter </a>
 */
public class XmlPackageReader extends DefaultHandler {
    // ----------------------------------------------------------------------
    // Constants
    // ----------------------------------------------------------------------
    public static final String  ENTITY_RESOLVER_PROPERTY_NAME = "org.drools.io.EntityResolver";

    /** Namespace URI for the general tags. */
    public static final String  RULES_NAMESPACE_URI           = "http://drools.org/rules";

    private static final String JAXP_SCHEMA_LANGUAGE          = "http://java.sun.com/xml/jaxp/properties/schemaLanguage";

    private static final String W3C_XML_SCHEMA                = "http://www.w3.org/2001/XMLSchema";

    // ----------------------------------------------------------------------
    // Instance members
    // ----------------------------------------------------------------------
    /** SAX parser. */
    private SAXParser           parser;

    /** isValidating */
    private boolean             isValidating                  = true;

    /** Locator for errors. */
    private Locator             locator;

    // private Map repo;

    /** Stack of configurations. */
    private LinkedList          configurationStack;

    /** Current configuration text. */
    private StringBuffer        characters;

    private Map                 handlers;

    private boolean             lastWasEndElement;

    private LinkedList          parents;

    private Object              peer;

    private Object              current;

    private PackageDescr        packageDescr;

    private boolean             inHandledRuleSubElement;

    private final MessageFormat       message                       = new MessageFormat( "({0}: {1}, {2}): {3}" );

    private final Map                 namespaces                    = new HashMap();

    EntityResolver              entityResolver;

    // ----------------------------------------------------------------------
    // Constructors
    // ----------------------------------------------------------------------

    /**
     * Construct.
     *
     * <p>
     * Uses the default JAXP SAX parser and the default classpath-based
     * <code>DefaultSemanticModule</code>.
     * </p>
     */
    public XmlPackageReader() {
        // init
        this.configurationStack = new LinkedList();
        this.parents = new LinkedList();

        this.handlers = new HashMap();

        this.handlers.put( "package",
                           new PackageHandler( this ) );
        this.handlers.put( "rule",
                           new RuleHandler( this ) );
        this.handlers.put( "query",
                           new QueryHandler( this ) );
        this.handlers.put( "attribute",
                           null );
        this.handlers.put( "function",
                           new FunctionHandler( this ) );

        // Conditional Elements
        this.handlers.put( "lhs",
                           new AndHandler( this ) );
        this.handlers.put( "and",
                           new AndHandler( this ) );
        this.handlers.put( "or",
                           new OrHandler( this ) );
        this.handlers.put( "not",
                           new NotHandler( this ) );
        this.handlers.put( "exists",
                           new ExistsHandler( this ) );
        this.handlers.put( "eval",
                           new EvalHandler( this ) );
        this.handlers.put( "column",
                           new ColumnHandler( this ) );

        // Field Constraints
        this.handlers.put( "literal",
                           new LiteralHandler( this ) );
        this.handlers.put( "predicate",
                           new PredicateHandler( this ) );
        this.handlers.put( "return-value",
                           new ReturnValueHandler( this ) );
        this.handlers.put( "field-binding",
                           new FieldBindingHandler( this ) );
        this.handlers.put( "bound-variable",
                           new BoundVariableHandler( this ) );

        initEntityResolver();

    }

    /**
     * Construct.
     *
     * <p>
     * Uses the default classpath-based <code>DefaultSemanticModule</code>.
     * </p>
     *
     * @param parser
     *            The SAX parser.
     */
    public XmlPackageReader(final SAXParser parser) {
        this.parser = parser;
    }

    // ----------------------------------------------------------------------
    // Instance methods
    // ----------------------------------------------------------------------

    /**
     * Read a <code>RuleSet</code> from a <code>Reader</code>.
     *
     * @param reader
     *            The reader containing the rule-set.
     *
     * @return The rule-set.
     */
    public PackageDescr read(final Reader reader) throws SAXException,
                                           IOException {
        return read( new InputSource( reader ) );
    }

    /**
     * Read a <code>RuleSet</code> from an <code>InputStream</code>.
     *
     * @param inputStream
     *            The input-stream containing the rule-set.
     *
     * @return The rule-set.
     */
    public PackageDescr read(final InputStream inputStream) throws SAXException,
                                                     IOException {
        return read( new InputSource( inputStream ) );
    }

    /**
     * Read a <code>RuleSet</code> from an <code>InputSource</code>.
     *
     * @param in
     *            The rule-set input-source.
     *
     * @return The rule-set.
     */
    public PackageDescr read(final InputSource in) throws SAXException,
                                            IOException {
        SAXParser localParser = null;
        if ( this.parser == null ) {
            final SAXParserFactory factory = SAXParserFactory.newInstance();
            factory.setNamespaceAware( true );

            final String isValidatingString = System.getProperty( "drools.schema.validating" );
            if ( System.getProperty( "drools.schema.validating" ) != null ) {
                this.isValidating = Boolean.getBoolean( "drools.schema.validating" );
            }

            if ( this.isValidating == true ) {
                factory.setValidating( true );
                try {
                    localParser = factory.newSAXParser();
                } catch ( final ParserConfigurationException e ) {
                    throw new RuntimeException( e.getMessage() );
                }

                try {
                    localParser.setProperty( XmlPackageReader.JAXP_SCHEMA_LANGUAGE,
                                             XmlPackageReader.W3C_XML_SCHEMA );
                } catch ( final SAXNotRecognizedException e ) {
                    boolean hideWarnings = Boolean.getBoolean( "drools.schema.hidewarnings" );
                    if ( !hideWarnings ) {
                        System.err.println( "Your SAX parser is not JAXP 1.2 compliant - turning off validation." );
                    }
                    localParser = null;
                }
            }

            if ( localParser == null ) {
                // not jaxp1.2 compliant so turn off validation
                try {
                    this.isValidating = false;
                    factory.setValidating( this.isValidating );
                    localParser = factory.newSAXParser();
                } catch ( final ParserConfigurationException e ) {
                    throw new RuntimeException( e.getMessage() );
                }
            }
        } else {
            localParser = this.parser;
        }

        if ( !localParser.isNamespaceAware() ) {
            throw new RuntimeException( "parser must be namespace-aware" );
        }

        localParser.parse( in,
                           this );

        return this.packageDescr;
    }

    void setPackageDescr(final PackageDescr packageDescr) {
        this.packageDescr = packageDescr;
    }

    public PackageDescr getPackageDescr() {
        return this.packageDescr;
    }

    /**
     * @see org.xml.sax.ContentHandler
     */
    public void setDocumentLocator(final Locator locator) {
        this.locator = locator;
    }

    /**
     * Get the <code>Locator</code>.
     *
     * @return The locator.
     */
    public Locator getLocator() {
        return this.locator;
    }

    public void startDocument() {
        this.isValidating = true;
        this.packageDescr = null;
        this.current = null;
        this.peer = null;
        this.lastWasEndElement = false;
        this.parents.clear();
        this.characters = null;
        this.configurationStack.clear();
        this.namespaces.clear();
    }

    /**
     * @param uri
     * @param localName
     * @param qname
     * @param attrs
     * @throws SAXException
     * @see org.xml.sax.ContentHandler
     *
     * @todo: better way to manage unhandled elements
     */
    public void startElement(final String uri,
                             final String localName,
                             final String qname,
                             final Attributes attrs) throws SAXException {
        // going down so no peer
        if ( !this.lastWasEndElement ) {
            this.peer = null;
        }

        final Handler handler = getHandler( localName );

        if ( (handler != null) && (!this.parents.isEmpty() && this.parents.getLast() instanceof RuleDescr) ) {
            this.inHandledRuleSubElement = true;
        }

        if ( handler == null ) {
            //            if ( ((this.inHandledRuleSubElement == false) && (this.parents.getLast() instanceof RuleDescr)) || (this.parents.getLast() instanceof PackageDescr) ) {
            //                throw new SAXParseException( "unknown tag '" + localName + "' in namespace '" + uri + "'",
            //                                             getLocator() );
            //            }
            // no handler so build up the configuration
            startConfiguration( localName,
                                attrs );
            return;
        }

        validate( uri,
                  localName,
                  handler );

        final Object node = handler.start( uri,
                                     localName,
                                     attrs );

        if ( node != null ) {
            this.parents.add( node );
            this.current = node;
        }
        this.lastWasEndElement = false;
    }

    /**
     * @param uri
     * @param localName
     * @param qname
     * @throws SAXException