Spring - Drools

 1package com.demo.project63;
 2
 3import java.util.Arrays;
 4import java.util.Collections;
 5import java.util.HashMap;
 6import java.util.Map;
 7
 8import lombok.extern.slf4j.Slf4j;
 9import org.kie.api.KieServices;
10import org.kie.api.builder.KieBuilder;
11import org.kie.api.builder.KieFileSystem;
12import org.kie.api.builder.KieModule;
13import org.kie.api.runtime.KieContainer;
14import org.kie.api.runtime.KieSession;
15import org.kie.internal.io.ResourceFactory;
16import org.springframework.boot.CommandLineRunner;
17import org.springframework.boot.SpringApplication;
18import org.springframework.boot.autoconfigure.SpringBootApplication;
19import org.springframework.context.annotation.Bean;
20
21@SpringBootApplication
22@Slf4j
23public class Main {
24
25    public static void main(String[] args) {
26        SpringApplication.run(Main.class, args);
27    }
28
29    @Bean
30    public CommandLineRunner sendData(KieContainer kContainer) {
31        return args -> {
32            //Simple
33            KieSession kieSession1 = kContainer.newKieSession();
34            Product p1 = new Product();
35            p1.setType("desktop");
36            p1.setRegions(Collections.emptyMap());
37            p1.setManufacturers(Collections.emptyList());
38            kieSession1.insert(p1);
39            kieSession1.fireAllRules();
40            kieSession1.dispose();
41            log.info("Discount on {} is {}", p1.getType(), p1.getDiscount());
42
43            //Iterates a Map.
44            KieSession kieSession2 = kContainer.newKieSession();
45            Product p2 = new Product();
46            p2.setType("laptop");
47            Map<String, String> r2 = new HashMap<>();
48            r2.put("region1", "A");
49            r2.put("region2", "B");
50            r2.put("region3", "C");
51            p2.setRegions(r2);
52            p2.setManufacturers(Collections.emptyList());
53            kieSession2.insert(p2);
54            kieSession2.fireAllRules();
55            kieSession2.dispose();
56            log.info("Discount on {} is {}", p2.getType(), p2.getDiscount());
57
58            //Iterates List
59            KieSession kieSession3 = kContainer.newKieSession();
60            Product p3 = new Product();
61            p3.setType("keyboard");
62            p3.setRegions(Collections.emptyMap());
63            p3.setManufacturers(Arrays.asList("Company1", "Company2"));
64            kieSession3.insert(p3);
65            kieSession3.fireAllRules();
66            kieSession3.dispose();
67            log.info("Discount on {} is {}", p3.getType(), p3.getDiscount());
68        };
69    }
70
71    @Bean
72    public KieContainer kieContainer() {
73        KieServices kieServices = KieServices.Factory.get();
74        KieFileSystem kieFileSystem = kieServices.newKieFileSystem();
75        kieFileSystem.write(ResourceFactory.newClassPathResource("product-discount.drl"));
76        KieBuilder kieBuilder = kieServices.newKieBuilder(kieFileSystem);
77        kieBuilder.buildAll();
78        KieModule kieModule = kieBuilder.getKieModule();
79        return kieServices.newKieContainer(kieModule.getReleaseId());
80    }
81
82}

 1import com.demo.project63.Product;
 2import java.util.Map;
 3
 4rule "Discount Based on Product"
 5	when
 6		$product: Product(type == "desktop")
 7	then
 8	    System.out.println("Discount provided for product");
 9		$product.setDiscount(15);
10	end
11
12
13rule "Discount Based on Store A,B,C"
14	when 
15		$product: Product($regions : regions)
16		$region: Map() from $regions
17		$entry: Map.Entry( $key: key, $val: value ) from $region.entrySet()
18		eval($val.equals("A") || $val.equals("B") || $val.equals("C"))
19	then
20	    System.out.println("Discount provided for product in specific region");
21		$product.setDiscount(10);
22	end
23
24rule "Discount Based Manufacturer"
25	when
26		$product: Product($manufacturers : manufacturers)
27		$manufacturer: String() from $manufacturers
28		eval($manufacturer.equals("Company1") || $manufacturer.equals("Company2"))
29	then
30	    System.out.println("Discount provided for manufacturer");
31		$product.setDiscount(5);
32	end

1./gradlew bootRun