org.drools.KnowledgeBaseFactory Maven / Gradle / Ivy

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package org.drools;

import java.util.Properties;

/**
 * 
 * This factory will create and return a KnowledgeBase instance, an optional KnowledgeBaseConfiguration
 * can be provided. The KnowlegeBaseConfiguration is also itself created from this factory.
 * 
 *  * KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();
 * 
 *
 * @see org.drools.KnowledgeBase
 */
public class KnowledgeBaseFactory {
    private static KnowledgeBaseProvider provider;

    /**
     * Create a new KnowledgeBase using the default KnowledgeBaseConfiguration
     * @return
     *     The KnowledgeBase
     */
    public static KnowledgeBase newKnowledgeBase() {
        return getKnowledgeBaseProvider().newKnowledgeBase();
    }

    /**
     * Create a new KnowledgeBase using the given KnowledgeBaseConfiguration
     * @return
     *     The KnowledgeBase
     */
    public static KnowledgeBase newKnowledgeBase(KnowledgeBaseConfiguration conf) {
        return getKnowledgeBaseProvider().newKnowledgeBase( conf );
    }

    /**
     * Create a KnowledgeBaseConfiguration on which properties can be set.
     * @return
     *     The KnowledgeBaseConfiguration.
     */
    public static KnowledgeBaseConfiguration newKnowledgeBaseConfiguration() {
        return getKnowledgeBaseProvider().newKnowledgeBaseConfiguration();
    }

    /**
     * Create a KnowledgeBaseConfiguration on which properties can be set. Use
     * the given properties file and ClassLoader - either of which can be null.
     * @return
     *     The KnowledgeBaseConfiguration.
     */
    public static KnowledgeBaseConfiguration newKnowledgeBaseConfiguration(Properties properties,
                                                                           ClassLoader classLoader) {
        return getKnowledgeBaseProvider().newKnowledgeBaseConfiguration( properties,
                                                                         classLoader );
    }

    private static synchronized void setKnowledgeBaseProvider(KnowledgeBaseProvider provider) {
        KnowledgeBaseFactory.provider = provider;
    }

    private static synchronized KnowledgeBaseProvider getKnowledgeBaseProvider() {
        if ( provider == null ) {
            loadProvider();
        }
        return provider;
    }

    private static void loadProvider() {
        try {
            // we didn't find anything in properties so lets try and us reflection
            Class cls = (Class) Class.forName( "org.drools.impl.KnowledgeBaseProviderImpl" );
            setKnowledgeBaseProvider( cls.newInstance() );
        } catch ( Exception e ) {
            throw new ProviderInitializationException( "Provider org.drools.impl.KnowledgeBaseProviderImpl could not be set.", e );
        }
    }
}