BAEL-812: List of Rules Engines in Java (#2319)

* spring beans DI examples

* fix-1: shortening examples

* List of Rules Engines in Java

* BAEL-812: Openl-Tablets example added

* BAEL-812: artifacts names changed

easy-rules/pom.xml

@@ -0,0 +1,15 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<groupId>com.baeldung.easyrules</groupId>
+	<artifactId>easy-rules</artifactId>
+	<version>1.0.0-SNAPSHOT</version>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.jeasy</groupId>
+		    <artifactId>easy-rules-core</artifactId>
+		    <version>3.0.0</version>
+		</dependency>
+	</dependencies>
+</project>

easy-rules/src/main/java/com/baeldung/easyrules/HelloWorldRule.java

@@ -0,0 +1,20 @@
+package com.baeldung.easyrules;
+
+import org.jeasy.rules.annotation.Action;
+import org.jeasy.rules.annotation.Condition;
+import org.jeasy.rules.annotation.Rule;
+
+@Rule(name = "Hello World rule", description = "Always say hello world")
+public class HelloWorldRule {
+
+    @Condition
+    public boolean when() {
+        return true;
+    }
+
+    @Action
+    public void then() throws Exception {
+        System.out.println("hello world");
+    }
+
+}

easy-rules/src/main/java/com/baeldung/easyrules/Launcher.java

@@ -0,0 +1,21 @@
+package com.baeldung.easyrules;
+
+import org.jeasy.rules.api.Facts;
+import org.jeasy.rules.api.Rules;
+import org.jeasy.rules.api.RulesEngine;
+import org.jeasy.rules.core.DefaultRulesEngine;
+
+public class Launcher {
+    public static void main(String... args) {
+        // create facts
+        Facts facts = new Facts();
+
+        // create rules
+        Rules rules = new Rules();
+        rules.register(new HelloWorldRule());
+
+        // create a rules engine and fire rules on known facts
+        RulesEngine rulesEngine = new DefaultRulesEngine();
+        rulesEngine.fire(rules, facts);
+    }
+}

openl-tablets/pom.xml

@@ -0,0 +1,23 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>com.baeldung.openltablets</groupId>
+  <artifactId>openl-tablets</artifactId>
+  <version>0.0.1-SNAPSHOT</version>
+ 	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+		<java.version>1.8</java.version>
+	</properties>
+	<dependencies>
+		<dependency>
+		   <groupId>org.openl</groupId>
+            <artifactId>org.openl.core</artifactId>
+		    <version>5.19.4</version>
+		</dependency>
+		<dependency>
+		    <groupId>org.openl.rules</groupId>
+            <artifactId>org.openl.rules</artifactId>
+		    <version>5.19.4</version>
+		</dependency>
+	</dependencies>
+</project>

openl-tablets/src/main/java/com/baeldung/openltablets/model/Case.java

@@ -0,0 +1,23 @@
+package com.baeldung.openltablets.model;
+
+public class Case {
+
+    private User user;
+    private int hourOfDay;
+
+    public User getUser() {
+        return user;
+    }
+
+    public void setUser(final User user) {
+        this.user = user;
+    }
+
+    public int getHourOfDay() {
+        return hourOfDay;
+    }
+
+    public void setHourOfDay(final int hourOfDay) {
+        this.hourOfDay = hourOfDay;
+    }
+}

openl-tablets/src/main/java/com/baeldung/openltablets/model/Greeting.java

@@ -0,0 +1,20 @@
+package com.baeldung.openltablets.model;
+
+public enum Greeting {
+
+    GOOD_MORNING("Good Morning"),
+    GOOD_AFTERNOON("Good Afternoon"),
+    GOOD_EVENING("Good Evening"),
+    GOOD_NIGHT("Good Night");
+
+    private final String literal;
+
+    private Greeting(final String literal) {
+        this.literal = literal;
+    }
+
+    public String getLiteral() {
+        return literal;
+    }
+
+}

openl-tablets/src/main/java/com/baeldung/openltablets/model/User.java

@@ -0,0 +1,14 @@
+package com.baeldung.openltablets.model;
+
+public class User {
+
+    private String name;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(final String name) {
+        this.name = name;
+    }
+}

openl-tablets/src/main/java/com/baeldung/openltablets/rules/IRule.java

@@ -0,0 +1,7 @@
+package com.baeldung.openltablets.rules;
+
+import com.baeldung.openltablets.model.Case;
+
+public interface IRule {
+    void helloUser(final Case aCase, final Response response);
+}

openl-tablets/src/main/java/com/baeldung/openltablets/rules/Main.java

@@ -0,0 +1,31 @@
+package com.baeldung.openltablets.rules;
+
+
+import java.time.LocalDateTime;
+
+import org.openl.rules.runtime.RulesEngineFactory;
+import org.openl.runtime.EngineFactory;
+
+import com.baeldung.openltablets.model.Case;
+import com.baeldung.openltablets.model.User;
+
+public class Main {
+    private IRule instance;
+
+    public static void main(String[] args) {
+        Main rules = new Main();
+        User user = new User();
+        user.setName("Donald Duck");
+        Case aCase = new Case();
+        aCase.setUser(user);
+        aCase.setHourOfDay(23);
+        rules.process(aCase);
+    }
+
+    public void process(Case aCase) {
+        final EngineFactory<IRule> engineFactory = new RulesEngineFactory<IRule>(getClass().getClassLoader()
+            .getResource("openltablets/HelloUser.xls"), IRule.class);
+        instance = engineFactory.newEngineInstance();
+        instance.helloUser(aCase, new Response());
+    }
+}

openl-tablets/src/main/java/com/baeldung/openltablets/rules/Response.java

@@ -0,0 +1,24 @@
+package com.baeldung.openltablets.rules;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class Response {
+    private String result;
+    private Map<String, String> map = new HashMap<>();
+    
+    public Response() { }
+    
+    public String getResult() {
+        return result;
+    }
+
+    public void setResult(final String s) {
+        result = s;
+    }
+
+    public Map<String, String> getMap() {
+        return map;
+    }
+
+}

rulebook/pom.xml

@@ -0,0 +1,15 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<groupId>com.baeldung.rulebook</groupId>
+	<artifactId>rulebook</artifactId>
+	<version>1.0.0-SNAPSHOT</version>
+
+	<dependencies>
+		<dependency>
+		  	<groupId>com.deliveredtechnologies</groupId>
+		    <artifactId>rulebook-core</artifactId>
+		    <version>0.6.2</version>
+		</dependency>
+	</dependencies>
+</project>

rulebook/src/main/java/com/baeldung/rulebook/HelloWorldRule.java

@@ -0,0 +1,17 @@
+package com.baeldung.rulebook;
+
+import com.deliveredtechnologies.rulebook.lang.RuleBookBuilder;
+import com.deliveredtechnologies.rulebook.model.RuleBook;
+
+public class HelloWorldRule {
+    public RuleBook<Object> defineHelloWorldRules() {
+
+        return RuleBookBuilder.create()
+            .addRule(rule -> rule.withNoSpecifiedFactType()
+                .then(f -> System.out.print("Hello ")))
+            .addRule(rule -> rule.withNoSpecifiedFactType()
+                .then(f -> System.out.println("World")))
+            .build();
+
+    }
+}

rulebook/src/main/java/com/baeldung/rulebook/Launcher.java

@@ -0,0 +1,12 @@
+package com.baeldung.rulebook;
+
+import com.deliveredtechnologies.rulebook.FactMap;
+
+public class Launcher {
+
+    public static void main(String[] args) {
+        HelloWorldRule ruleBook = new HelloWorldRule();
+        ruleBook.defineHelloWorldRules()
+            .run(new FactMap<>());
+    }
+}

spring-core/src/main/java/com/baeldung/autowired/TypesOfBeanInjectionSpring.java

@@ -0,0 +1,70 @@
+package com.baeldung.autowired;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
+import org.springframework.stereotype.Service;
+
+@SpringBootApplication
+public class TypesOfBeanInjectionSpring {
+    private final UserService userService;
+
+    @Autowired // the @Autowired can even be omitted, in case there's only one explicit constructor
+    public TypesOfBeanInjectionSpring(UserService userService) {
+        this.userService = userService;
+    }
+    
+    public static void main(String[] args) {
+        SpringApplication.run(TypesOfBeanInjectionSpring.class, args);
+    }
+
+    @Bean
+    CommandLineRunner runIt() {
+        return args -> {
+            userService.listUsers()
+                .stream()
+                .forEach(System.out::println);
+        };
+    }
+}
+
+class User {
+    private String name;
+
+    public User(String name) {
+        this.name = name;
+    }
+
+    // getters and setters ...
+    public String getName() {
+        return this.name;
+    }
+
+    public String toString() {
+        return name;
+    }
+
+}
+
+interface UserService {
+    List<User> listUsers();
+}
+
+@Service
+class UserServiceImpl implements UserService {
+
+    @Override
+    public List<User> listUsers() {
+        ArrayList<User> users = new ArrayList<>(3);
+        users.add(new User("Snoopy"));
+        users.add(new User("Woodstock"));
+        users.add(new User("Charlie Brown"));
+        return users;
+    }
+
+}

spring-core/src/test/java/com/baeldung/autowired/TypesOfBeanInjectionSpringIntegrationTest.java

@@ -0,0 +1,25 @@
+package com.baeldung.autowired;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit4.SpringRunner;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest
+public class TypesOfBeanInjectionSpringIntegrationTest {
+    @Autowired
+    UserService userService;
+
+    private static final String[] expected = new String[] { "Snoopy", "Woodstock", "Charlie Brown" };
+
+    @Test
+    public void givenDI_whenInjectObject_thenUserNamesAreListed() {
+        Assert.assertArrayEquals(expected, userService.listUsers()
+            .stream()
+            .map(User::getName)
+            .toArray());
+    }
+}