BAEL-1524: Chain of Responsibility Design Pattern in Java (#3573)

* BAEL-1422: measure performance of Random and ThreadLocalRandom using JMH

* BAEL-1422: updated benchmarking examples of Random and ThreadLocalRandom to use newWorkStealingPool that leverages ForkJoinPool

* BAEL-1422: refactored benchmarking examples for comparing performance of ThreadLocalRandom and Random
- initialised the collection of Callable before running benchmarking
- removed for loop for submitting task and instead used executor.invokeAll(collection_of_callable)

* BAEL-1282: added TDD type junit tests for geospatial queries elasticsearch

* BAEL-1524: added example for chain of responsibility design pattern

* BAEL-1524: added BDD style jUnit test to test unknown handler in ChainOfResponsibility design pattern

* BAEL-1524: refactored ChainOfResponsibility design pattern example

* BAEL-1524: refactored ChainOfResponsibility design pattern example

* BAEL-1524: updated ChainOfResponsibility design pattern example

* BAEL-1524: updated ChainOfResponsibility design pattern example

core-java/src/main/java/com/baeldung/designpatterns/chainofresponsibility/AuthenticationProcessor.java

@@ -0,0 +1,13 @@
+package com.baeldung.designpatterns.chainofresponsibility;
+
+public abstract class AuthenticationProcessor {
+
+    // next element in chain or responsibility
+    public AuthenticationProcessor nextProcessor;
+    
+    public AuthenticationProcessor(AuthenticationProcessor nextProcessor) {
+        this.nextProcessor = nextProcessor;
+    }
+
+    public abstract boolean isAuthorized(AuthenticationProvider authProvider);
+}

core-java/src/main/java/com/baeldung/designpatterns/chainofresponsibility/AuthenticationProvider.java

@@ -0,0 +1,5 @@
+package com.baeldung.designpatterns.chainofresponsibility;
+
+public interface AuthenticationProvider {
+
+}

core-java/src/main/java/com/baeldung/designpatterns/chainofresponsibility/OAuthAuthenticationProcessor.java

@@ -0,0 +1,21 @@
+package com.baeldung.designpatterns.chainofresponsibility;
+
+public class OAuthAuthenticationProcessor extends AuthenticationProcessor {
+
+    public OAuthAuthenticationProcessor(AuthenticationProcessor nextProcessor) {
+        super(nextProcessor);
+    }
+
+    @Override
+    public boolean isAuthorized(AuthenticationProvider authProvider) {
+
+        if (authProvider instanceof OAuthTokenProvider) {
+            return Boolean.TRUE;
+        } else if (nextProcessor != null) {
+            return nextProcessor.isAuthorized(authProvider);
+        } else {
+            return Boolean.FALSE;
+        }
+    }
+
+}

core-java/src/main/java/com/baeldung/designpatterns/chainofresponsibility/OAuthTokenProvider.java

@@ -0,0 +1,5 @@
+package com.baeldung.designpatterns.chainofresponsibility;
+
+public class OAuthTokenProvider implements AuthenticationProvider {
+
+}

core-java/src/main/java/com/baeldung/designpatterns/chainofresponsibility/SamlAuthenticationProvider.java

@@ -0,0 +1,5 @@
+package com.baeldung.designpatterns.chainofresponsibility;
+
+public class SamlAuthenticationProvider implements AuthenticationProvider {
+
+}

core-java/src/main/java/com/baeldung/designpatterns/chainofresponsibility/UsernamePasswordAuthenticationProcessor.java

@@ -0,0 +1,20 @@
+package com.baeldung.designpatterns.chainofresponsibility;
+
+public class UsernamePasswordAuthenticationProcessor extends AuthenticationProcessor {
+
+    public UsernamePasswordAuthenticationProcessor(AuthenticationProcessor nextProcessor) {
+        super(nextProcessor);
+    }
+
+    @Override
+    public boolean isAuthorized(AuthenticationProvider authProvider) {
+        if (authProvider instanceof UsernamePasswordProvider) {
+            return Boolean.TRUE;
+        } else if (nextProcessor != null) {
+            return nextProcessor.isAuthorized(authProvider);
+        } else {
+            return Boolean.FALSE;
+        }
+    }
+
+}

core-java/src/main/java/com/baeldung/designpatterns/chainofresponsibility/UsernamePasswordProvider.java

@@ -0,0 +1,5 @@
+package com.baeldung.designpatterns.chainofresponsibility;
+
+public class UsernamePasswordProvider implements AuthenticationProvider {
+
+}

core-java/src/test/java/com/baeldung/designpatterns/chainofresponsibility/ChainOfResponsibilityTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.designpatterns.chainofresponsibility;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertTrue;
+
+public class ChainOfResponsibilityTest {
+
+    private static AuthenticationProcessor getChainOfAuthProcessor() {
+
+        AuthenticationProcessor oAuthProcessor = new OAuthAuthenticationProcessor(null);
+        AuthenticationProcessor unamePasswordProcessor = new UsernamePasswordAuthenticationProcessor(oAuthProcessor);
+        return unamePasswordProcessor;
+    }
+
+    @Test
+    public void givenOAuthProvider_whenCheckingAuthorized_thenSuccess() {
+        AuthenticationProcessor authProcessorChain = getChainOfAuthProcessor();
+        boolean isAuthorized = authProcessorChain.isAuthorized(new OAuthTokenProvider());
+        assertTrue(isAuthorized);
+    }
+
+    @Test
+    public void givenUsernamePasswordProvider_whenCheckingAuthorized_thenSuccess() {
+        AuthenticationProcessor authProcessorChain = getChainOfAuthProcessor();
+        boolean isAuthorized = authProcessorChain.isAuthorized(new UsernamePasswordProvider());
+        assertTrue(isAuthorized);
+    }
+
+    @Test
+    public void givenSamlAuthProvider_whenCheckingAuthorized_thenFailure() {
+        AuthenticationProcessor authProcessorChain = getChainOfAuthProcessor();
+        boolean isAuthorized = authProcessorChain.isAuthorized(new SamlAuthenticationProvider());
+        assertTrue(!isAuthorized);
+    }
+
+}