/*
* Copyright 2010 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.
*/
package org.drools.examples.templates;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.drools.KnowledgeBase;
import org.drools.KnowledgeBaseFactory;
import org.drools.builder.KnowledgeBuilder;
import org.drools.builder.KnowledgeBuilderError;
import org.drools.builder.KnowledgeBuilderFactory;
import org.drools.builder.ResourceType;
import org.drools.decisiontable.ExternalSpreadsheetCompiler;
import org.drools.io.ResourceFactory;
import org.drools.io.impl.ByteArrayResource;
import org.drools.runtime.StatefulKnowledgeSession;
/**
* This shows off a very simple rule template where the data provider is a spreadsheet.
*/
public class SimpleRuleTemplateExample {
public static void main(String[] args) {
SimpleRuleTemplateExample launcher = new SimpleRuleTemplateExample();
launcher.executeExample();
}
private void executeExample() {
//BUILD THE KBASE
final KnowledgeBase kbase = this.buildKBase();
//GET A KSESSION
StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession();
//now create some test data
ksession.insert( new Cheese( "stilton",
42 ) );
ksession.insert( new Person( "michael",
"stilton",
42 ) );
final List<String> list = new ArrayList<String>();
ksession.setGlobal( "list",
list );
ksession.fireAllRules();
System.out.println(list);
ksession.dispose();
}
/**
* Creates a new kbase containing the rules generated from the xls file and
* the template.
* @return
* @throws IOException
*/
private KnowledgeBase buildKBase() {
//first we compile the decision table into a whole lot of rules.
final ExternalSpreadsheetCompiler converter = new ExternalSpreadsheetCompiler();
//the data we are interested in starts at row 2, column 2 (e.g. B2)
String drl = null;
try {
drl = converter.compile(getSpreadsheetStream(), getRulesStream(), 2, 2);
} catch (IOException e) {
throw new IllegalArgumentException("Could not read spreadsheet or rules stream." ,e);
}
//compile the drl
KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();
kbuilder.add(new ByteArrayResource(drl.getBytes()), ResourceType.DRL);
//compilation errors?
if (kbuilder.hasErrors()) {
System.out.println("Error compiling resources:");
Iterator<KnowledgeBuilderError> errors = kbuilder.getErrors().iterator();
while (errors.hasNext()) {
System.out.println("\t" + errors.next().getMessage());
}
throw new IllegalStateException("Error compiling resources");
}
//Uncomment to see the rules
//System.out.println(drl);
//BUILD KBASE
KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();
kbase.addKnowledgePackages(kbuilder.getKnowledgePackages());
return kbase;
}
private InputStream getSpreadsheetStream() throws IOException {
return ResourceFactory.newClassPathResource("org/drools/examples/templates/ExampleCheese.xls").getInputStream();
}
private InputStream getRulesStream() throws IOException {
return ResourceFactory.newClassPathResource("org/drools/examples/templates/Cheese.drt").getInputStream();
}
}