BAEL-804 A guide to Spring Drools (#1776)

* BAEL-804  A guide to Spring Drools

* BAEL-804  A guide to Spring Drools

* BAEL-804  A guide to Spring Drools

spring-drools/src/main/java/com/baeldung/spring/drools/Application.java

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+package com.baeldung.spring.drools;
+
+
+import com.baeldung.spring.drools.model.Applicant;
+import com.baeldung.spring.drools.model.Product;
+import com.baeldung.spring.drools.model.SuggestedRole;
+import com.baeldung.spring.drools.service.ApplicantService;
+import com.baeldung.spring.drools.service.ProductService;
+import org.kie.api.KieServices;
+import org.kie.api.runtime.KieContainer;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Import;
+
+@SpringBootApplication
+@Import(DroolConfiguration.class)
+public class Application {
+
+    public static void main(String[] args) {
+        ApplicationContext ctx = SpringApplication.run(Application.class, args);
+        ApplicantService applicantService=(ApplicantService)ctx.getBean("applicantService");
+        applicantService.suggestARoleForApplicant(new Applicant("Baljeet",37,1200000.0,8),new SuggestedRole());
+
+        ProductService productService=(ProductService)ctx.getBean("productService");
+        Product returnedProduct=productService.applyLabelToProduct(new Product("Microwave","Book"));
+    }
+
+}

spring-drools/src/main/java/com/baeldung/spring/drools/DroolConfiguration.java

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+package com.baeldung.spring.drools;
+
+import com.baeldung.spring.drools.service.ApplicantService;
+import com.baeldung.spring.drools.service.ProductService;
+import org.kie.api.KieBase;
+import org.kie.api.KieServices;
+import org.kie.api.builder.*;
+import org.kie.api.runtime.KieContainer;
+import org.kie.api.runtime.KieSession;
+import org.kie.internal.io.ResourceFactory;
+import org.kie.spring.KModuleBeanFactoryPostProcessor;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.io.Resource;
+import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
+import org.springframework.core.io.support.ResourcePatternResolver;
+
+import java.io.IOException;
+
+@Configuration
+public class DroolConfiguration {
+
+    private static final String RULES_PATH = "com/baeldung/spring/drools/rules/";
+
+    @Bean
+    public KieFileSystem kieFileSystem() throws IOException {
+        KieFileSystem kieFileSystem = getKieServices().newKieFileSystem();
+        for (Resource file : getRuleFiles()) {
+            kieFileSystem.write(ResourceFactory.newClassPathResource(RULES_PATH + file.getFilename(), "UTF-8"));
+        }
+        return kieFileSystem;
+    }
+
+    private Resource[] getRuleFiles() throws IOException {
+        ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
+        return resourcePatternResolver.getResources("classpath*:" + RULES_PATH + "**/*.*");
+    }
+
+    @Bean
+    public KieContainer kieContainer() throws IOException {
+        final KieRepository kieRepository = getKieServices().getRepository();
+
+        kieRepository.addKieModule(new KieModule() {
+            public ReleaseId getReleaseId() {
+                return kieRepository.getDefaultReleaseId();
+            }
+        });
+
+        KieBuilder kieBuilder = getKieServices().newKieBuilder(kieFileSystem());
+        kieBuilder.buildAll();
+
+        return getKieServices().newKieContainer(kieRepository.getDefaultReleaseId());
+    }
+
+    private KieServices getKieServices() {
+        return KieServices.Factory.get();
+    }
+
+    @Bean
+    public KieBase kieBase() throws IOException {
+        return kieContainer().getKieBase();
+    }
+
+    @Bean
+    public KieSession kieSession() throws IOException {
+        return kieContainer().newKieSession();
+    }
+
+    @Bean
+    public ApplicantService getApplicantService(){
+        return new ApplicantService();
+    }
+
+    @Bean
+    public ProductService getProductService(KieContainer kieContainer){
+        return new ProductService();
+    }
+
+    @Bean
+    public KModuleBeanFactoryPostProcessor kiePostProcessor() {
+        return new KModuleBeanFactoryPostProcessor();
+    }
+}

spring-drools/src/main/java/com/baeldung/spring/drools/model/Applicant.java

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+package com.baeldung.spring.drools.model;
+
+public class Applicant {
+
+    private String name;
+    private int age;
+    private double currentSalary;
+    private int experienceInYears;
+
+    public Applicant(String name, int age, Double currentSalary, int experienceInYears) {
+        this.name = name;
+        this.age = age;
+        this.currentSalary = currentSalary;
+        this.experienceInYears = experienceInYears;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    public Double getCurrentSalary() {
+        return currentSalary;
+    }
+
+    public void setCurrentSalary(Double currentSalary) {
+        this.currentSalary = currentSalary;
+    }
+
+    public int getExperienceInYears() {
+        return experienceInYears;
+    }
+
+    public void setExperienceInYears(int experienceInYears) {
+        this.experienceInYears = experienceInYears;
+    }
+}

spring-drools/src/main/java/com/baeldung/spring/drools/model/Product.java

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+package com.baeldung.spring.drools.model;
+
+public class Product {
+    private String name;
+    private String type;
+
+    private String label;
+
+    public Product(String name, String type) {
+        this.name = name;
+        this.type = type;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getType() {
+        return type;
+    }
+
+    public void setType(String type) {
+        this.type = type;
+    }
+
+    public String getLabel() {
+        return label;
+    }
+
+    public void setLabel(String label) {
+        this.label = label;
+    }
+
+}

spring-drools/src/main/java/com/baeldung/spring/drools/model/SuggestedRole.java

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+package com.baeldung.spring.drools.model;
+
+public class SuggestedRole {
+
+    private String role;
+
+    public String getRole() {
+        return role;
+    }
+
+    public void setRole(String role) {
+        this.role = role;
+    }
+}

spring-drools/src/main/java/com/baeldung/spring/drools/service/ApplicantService.java

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+package com.baeldung.spring.drools.service;
+
+import com.baeldung.spring.drools.model.Applicant;
+import com.baeldung.spring.drools.model.SuggestedRole;
+import org.kie.api.runtime.KieContainer;
+import org.kie.api.runtime.KieSession;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+@Service
+public class ApplicantService {
+
+    @Autowired
+    private KieContainer kieContainer;
+
+    public SuggestedRole suggestARoleForApplicant(Applicant applicant,SuggestedRole suggestedRole){
+        KieSession kieSession = kieContainer.newKieSession();
+        kieSession.insert(applicant);
+        kieSession.setGlobal("suggestedRole",suggestedRole);
+        kieSession.fireAllRules();
+        System.out.println(suggestedRole.getRole());
+        return  suggestedRole;
+
+    }
+}

spring-drools/src/main/java/com/baeldung/spring/drools/service/ProductService.java

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+package com.baeldung.spring.drools.service;
+
+import com.baeldung.spring.drools.model.Product;
+import org.kie.api.runtime.KieContainer;
+import org.kie.api.runtime.KieSession;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+@Service
+public class ProductService {
+
+    @Autowired
+    private  KieContainer kieContainer;
+
+    public Product applyLabelToProduct(Product product){
+        KieSession kieSession = kieContainer.newKieSession();
+        kieSession.insert(product);
+        kieSession.fireAllRules();
+        System.out.println(product.getLabel());
+        return  product;
+
+    }
+
+}

spring-drools/src/main/resources/com/baeldung/spring/drools/rules/SuggestApplicant.drl

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+package com.baeldung.spring.drools.rules;
+
+import com.baeldung.spring.drools.model.Applicant;
+
+global com.baeldung.spring.drools.model.SuggestedRole suggestedRole;
+
+dialect  "mvel"
+
+rule "Suggest Manager Role"
+    when
+        Applicant(experienceInYears > 10)
+        Applicant(currentSalary > 1000000 && currentSalary <= 2500000)
+    then
+        suggestedRole.setRole("Manager");
+end
+
+rule "Suggest Senior developer Role"
+    when
+        Applicant(experienceInYears > 5 && experienceInYears <= 10)
+        Applicant(currentSalary > 500000 && currentSalary <= 1500000)
+    then
+        suggestedRole.setRole("Senior developer");
+end
+
+rule "Suggest Developer Role"
+    when
+        Applicant(experienceInYears > 0 && experienceInYears <= 5)
+        Applicant(currentSalary > 200000 && currentSalary <= 1000000)
+    then
+        suggestedRole.setRole("Developer");
+end

spring-drools/src/test/java/com/baeldung/spring/drools/service/ApplicantServiceIntegrationTest.java

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+package com.baeldung.spring.drools.service;
+
+import com.baeldung.spring.drools.Application;
+import com.baeldung.spring.drools.DroolConfiguration;
+import com.baeldung.spring.drools.model.Applicant;
+import com.baeldung.spring.drools.model.SuggestedRole;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+import static junit.framework.Assert.assertNull;
+import static junit.framework.TestCase.assertEquals;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes = {DroolConfiguration.class})
+public class ApplicantServiceIntegrationTest {
+
+    @Autowired
+    ApplicantService applicantService;
+
+    @Test
+    public void whenCriteriaMatching_ThenSuggestManagerRole(){
+        Applicant applicant=new Applicant("Davis",37,1600000.0,11);
+        SuggestedRole suggestedRole=new SuggestedRole();
+        applicantService.suggestARoleForApplicant(applicant,suggestedRole);
+        assertEquals("Manager",suggestedRole.getRole());
+    }
+
+    @Test
+    public void whenCriteriaMatching_ThenSuggestSeniorDeveloperRole(){
+        Applicant applicant=new Applicant("John",37,1200000.0,8);
+        SuggestedRole suggestedRole=new SuggestedRole();
+        applicantService.suggestARoleForApplicant(applicant,suggestedRole);
+        assertEquals("Senior developer",suggestedRole.getRole());
+    }
+    @Test
+    public void whenCriteriaMatching_ThenSuggestDeveloperRole(){
+        Applicant applicant=new Applicant("Davis",37,800000.0,3);
+        SuggestedRole suggestedRole=new SuggestedRole();
+        applicantService.suggestARoleForApplicant(applicant,suggestedRole);
+        assertEquals("Developer",suggestedRole.getRole());
+    }
+    @Test
+    public void whenCriteriaNotMatching_ThenNoRole(){
+        Applicant applicant=new Applicant("John",37,1200000.0,5);
+        SuggestedRole suggestedRole=new SuggestedRole();
+        applicantService.suggestARoleForApplicant(applicant,suggestedRole);
+        assertNull(suggestedRole.getRole());
+    }
+}

spring-drools/src/test/java/com/baeldung/spring/drools/service/ProductServiceIntegrationTest.java

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+package com.baeldung.spring.drools.service;
+
+import com.baeldung.spring.drools.Application;
+import com.baeldung.spring.drools.DroolConfiguration;
+import com.baeldung.spring.drools.model.Product;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+import static junit.framework.TestCase.assertEquals;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes = {DroolConfiguration.class})
+public class ProductServiceIntegrationTest {
+
+    @Autowired
+    ProductService productService;
+
+    @Test
+    public void whenProductTypeElectronic_ThenLabelBarcode(){
+        Product product=new Product("Microwave","Electronic");
+        product=productService.applyLabelToProduct(product);
+        assertEquals("BarCode",product.getLabel());
+    }
+
+    @Test
+    public void whenProductTypeBook_ThenLabelIsbn(){
+        Product product=new Product("AutoBiography","Book");
+        product=productService.applyLabelToProduct(product);
+        assertEquals("ISBN",product.getLabel());
+    }
+}