Spring Integration Subflows

Issue: BAEL-2276

spring-integration/src/main/java/com/baeldung/subflows/discardflow/FilterExample.java

@@ -0,0 +1,57 @@
+package com.baeldung.subflows.discardflow;
+
+import java.util.Collection;
+import org.springframework.context.annotation.Bean;
+import org.springframework.integration.annotation.Gateway;
+import org.springframework.integration.annotation.IntegrationComponentScan;
+import org.springframework.integration.annotation.MessagingGateway;
+import org.springframework.integration.channel.QueueChannel;
+import org.springframework.integration.config.EnableIntegration;
+import org.springframework.integration.dsl.IntegrationFlow;
+
+@EnableIntegration
+@IntegrationComponentScan
+public class FilterExample {
+    @MessagingGateway
+    public interface NumbersClassifier {
+        @Gateway(requestChannel = "classify.input")
+        void classify(Collection<Integer> numbers);
+    }
+
+    @Bean
+    QueueChannel multipleofThreeChannel() {
+        return new QueueChannel();
+    }
+
+    @Bean
+    QueueChannel remainderIsOneChannel() {
+        return new QueueChannel();
+    }
+
+    @Bean
+    QueueChannel remainderIsTwoChannel() {
+        return new QueueChannel();
+    }
+    boolean isMultipleOfThree(Integer number) {
+        return number % 3 == 0;
+    }
+
+    boolean isRemainderOne(Integer number) {
+        return number % 3 == 1;
+    }
+
+    boolean isRemainderTwo(Integer number) {
+        return number % 3 == 2;
+    }
+    @Bean
+    public IntegrationFlow classify() {
+        return flow -> flow.split()
+            .<Integer> filter(this::isMultipleOfThree, notMultiple  -> notMultiple 
+                .discardFlow(oneflow  -> oneflow 
+                    .<Integer> filter(this::isRemainderOne, 
+                    twoflow  -> twoflow .discardChannel("remainderIsTwoChannel"))
+                .channel("remainderIsOneChannel")))
+            .channel("multipleofThreeChannel");
+    }
+
+}

spring-integration/src/main/java/com/baeldung/subflows/publishsubscribechannel/PublishSubscibeChannelExample.java

@@ -1,15 +1,13 @@
 package com.baeldung.subflows.publishsubscribechannel;
 
-import java.util.Arrays;
 import java.util.Collection;
 
-import org.springframework.context.ConfigurableApplicationContext;
-import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.integration.annotation.Gateway;
 import org.springframework.integration.annotation.IntegrationComponentScan;
 import org.springframework.integration.annotation.MessagingGateway;
-import org.springframework.integration.channel.DirectChannel;
+
+import org.springframework.integration.channel.QueueChannel;
 import org.springframework.integration.config.EnableIntegration;
 import org.springframework.integration.dsl.IntegrationFlow;
 
@@ -18,46 +16,45 @@ import org.springframework.integration.dsl.IntegrationFlow;
 public class PublishSubscibeChannelExample {
     @MessagingGateway
     public interface NumbersClassifier {
-        @Gateway(requestChannel = "flow.input")
+        @Gateway(requestChannel = "classify.input")
-        void flow(Collection<Integer> numbers);
+        void classify(Collection<Integer> numbers);
     }
 
     @Bean
-    DirectChannel multipleof3Channel() {
+    QueueChannel multipleofThreeChannel() {
-        return new DirectChannel();
+        return new QueueChannel();
     }
 
     @Bean
-    DirectChannel remainderIs1Channel() {
+    QueueChannel remainderIsOneChannel() {
-        return new DirectChannel();
+        return new QueueChannel();
     }
 
     @Bean
-    DirectChannel remainderIs2Channel() {
+    QueueChannel remainderIsTwoChannel() {
-        return new DirectChannel();
+        return new QueueChannel();
+    }
+    boolean isMultipleOfThree(Integer number) {
+        return number % 3 == 0;
     }
 
+    boolean isRemainderOne(Integer number) {
+        return number % 3 == 1;
+    }
+
+    boolean isRemainderTwo(Integer number) {
+        return number % 3 == 2;
+    }
     @Bean
-    public IntegrationFlow flow() {
+    public IntegrationFlow classify() {
         return flow -> flow.split()
-            .publishSubscribeChannel(s -> s.subscribe(f -> f.<Integer> filter(p -> p % 3 == 0)
+            .publishSubscribeChannel(subscription -> subscription.subscribe(subflow -> subflow.<Integer> filter(this::isMultipleOfThree)
-                .channel("multipleof3Channel"))
+                .channel("multipleofThreeChannel"))
-                .subscribe(f -> f.<Integer> filter(p -> p % 3 == 1)
+                .subscribe(subflow -> subflow.<Integer> filter(this::isRemainderOne)
-                    .channel("remainderIs1Channel"))
+                    .channel("remainderIsOneChannel"))
-                .subscribe(f -> f.<Integer> filter(p -> p % 3 == 2)
+                .subscribe(subflow -> subflow.<Integer> filter(this::isRemainderTwo)
-                    .channel("remainderIs2Channel")));
+                    .channel("remainderIsTwoChannel")));
     }
     
-    public static void main(String[] args) {
+
-        final ConfigurableApplicationContext ctx = new AnnotationConfigApplicationContext(PublishSubscibeChannelExample.class);
-        DirectChannel multipleof3Channel = ctx.getBean("multipleof3Channel", DirectChannel.class);
-        multipleof3Channel.subscribe(x -> System.out.println("multipleof3Channel: " + x));
-        DirectChannel remainderIs1Channel = ctx.getBean("remainderIs1Channel", DirectChannel.class);
-        remainderIs1Channel.subscribe(x -> System.out.println("remainderIs1Channel: " + x));
-        DirectChannel remainderIs2Channel = ctx.getBean("remainderIs2Channel", DirectChannel.class);
-        remainderIs2Channel.subscribe(x -> System.out.println("remainderIs2Channel: " + x));
-        ctx.getBean(NumbersClassifier.class)
-            .flow(Arrays.asList(1, 2, 3, 4, 5, 6));
-        ctx.close();
-    }
 }

spring-integration/src/main/java/com/baeldung/subflows/routeToRecipients/RouteToRecipientsExample.java

@@ -1,15 +1,12 @@
-package com.baeldung.subflows.routeToRecipients;
+package com.baeldung.subflows.routetorecipients;
 
-import java.util.Arrays;
 import java.util.Collection;
 
-import org.springframework.context.ConfigurableApplicationContext;
-import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.integration.annotation.Gateway;
 import org.springframework.integration.annotation.IntegrationComponentScan;
 import org.springframework.integration.annotation.MessagingGateway;
-import org.springframework.integration.channel.DirectChannel;
+import org.springframework.integration.channel.QueueChannel;
 import org.springframework.integration.config.EnableIntegration;
 import org.springframework.integration.dsl.IntegrationFlow;
 
@@ -18,44 +15,46 @@ import org.springframework.integration.dsl.IntegrationFlow;
 public class RouteToRecipientsExample {
     @MessagingGateway
     public interface NumbersClassifier {
-        @Gateway(requestChannel = "flow.input")
+        @Gateway(requestChannel = "classify.input")
-        void flow(Collection<Integer> numbers);
+        void classify(Collection<Integer> numbers);
     }
 
     @Bean
-    DirectChannel multipleof3Channel() {
+    QueueChannel multipleofThreeChannel() {
-        return new DirectChannel();
+        return new QueueChannel();
     }
 
     @Bean
-    DirectChannel remainderIs1Channel() {
+    QueueChannel remainderIsOneChannel() {
-        return new DirectChannel();
+        return new QueueChannel();
     }
 
     @Bean
-    DirectChannel remainderIs2Channel() {
+    QueueChannel remainderIsTwoChannel() {
-        return new DirectChannel();
+        return new QueueChannel();
+    }
+    boolean isMultipleOfThree(Integer number) {
+        return number % 3 == 0;
+    }
+
+    boolean isRemainderOne(Integer number) {
+        return number % 3 == 1;
+    }
+
+    boolean isRemainderTwo(Integer number) {
+        return number % 3 == 2;
     }
 
     @Bean
-    public IntegrationFlow flow() {
+    public IntegrationFlow classify() {
         return flow -> flow.split()
-            .routeToRecipients(r -> r.<Integer> recipient("multipleof3Channel", p -> p % 3 == 0)// filter
+            .routeToRecipients(route -> route
-                .<Integer> recipient("remainderIs1Channel", p -> p % 3 == 1)
+                .recipientFlow(subflow -> subflow
-                .recipientFlow(sf -> sf.<Integer> filter(p -> p % 3 == 2)
+                    .<Integer> filter(this::isMultipleOfThree)
-                    .channel("remainderIs2Channel")));
+                    .channel("multipleofThreeChannel"))
+                .<Integer> recipient("remainderIsOneChannel",this::isRemainderOne)
+                .<Integer> recipient("remainderIsTwoChannel",this::isRemainderTwo));
     }
    
-    public static void main(String[] args) {
+
-        final ConfigurableApplicationContext ctx = new AnnotationConfigApplicationContext(RouteToRecipientsExample.class);
-        DirectChannel multipleof3Channel = ctx.getBean("multipleof3Channel", DirectChannel.class);
-        multipleof3Channel.subscribe(x -> System.out.println("multipleof3Channel: " + x));
-        DirectChannel remainderIs1Channel = ctx.getBean("remainderIs1Channel", DirectChannel.class);
-        remainderIs1Channel.subscribe(x -> System.out.println("remainderIs1Channel: " + x));
-        DirectChannel remainderIs2Channel = ctx.getBean("remainderIs2Channel", DirectChannel.class);
-        remainderIs2Channel.subscribe(x -> System.out.println("remainderIs2Channel: " + x));
-        ctx.getBean(NumbersClassifier.class)
-            .flow(Arrays.asList(1, 2, 3, 4, 5, 6));
-        ctx.close();
-    }
 }

spring-integration/src/main/java/com/baeldung/subflows/separateflows/SeparateFlowsExample.java

@@ -1,15 +1,13 @@
 package com.baeldung.subflows.separateflows;
 
-import java.util.Arrays;
 import java.util.Collection;
 
-import org.springframework.context.ConfigurableApplicationContext;
-import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.integration.annotation.Gateway;
 import org.springframework.integration.annotation.IntegrationComponentScan;
 import org.springframework.integration.annotation.MessagingGateway;
-import org.springframework.integration.channel.DirectChannel;
+
+import org.springframework.integration.channel.QueueChannel;
 import org.springframework.integration.config.EnableIntegration;
 import org.springframework.integration.dsl.IntegrationFlow;
 
@@ -18,66 +16,62 @@ import org.springframework.integration.dsl.IntegrationFlow;
 public class SeparateFlowsExample {
     @MessagingGateway
     public interface NumbersClassifier {
-        @Gateway(requestChannel = "multipleof3Flow.input")
+        @Gateway(requestChannel = "multipleOfThreeFlow.input")
-        void multipleof3(Collection<Integer> is);
+        void multipleofThree(Collection<Integer> numbers);
 
-        @Gateway(requestChannel = "remainderIs1Flow.input")
+        @Gateway(requestChannel = "remainderIsOneFlow.input")
-        void remainderIs1(Collection<Integer> is);
+        void remainderIsOne(Collection<Integer> numbers);
 
-        @Gateway(requestChannel = "remainderIs2Flow.input")
+        @Gateway(requestChannel = "remainderIsTwoFlow.input")
-        void remainderIs2(Collection<Integer> numbers);
+        void remainderIsTwo(Collection<Integer> numbers);
     }
     
     @Bean
-    DirectChannel multipleof3Channel() {
+    QueueChannel multipleOfThreeChannel() {
-        return new DirectChannel();
+        return new QueueChannel();
     }
  
     @Bean
-    DirectChannel remainderIs1Channel() {
+    QueueChannel remainderIsOneChannel() {
-        return new DirectChannel();
+        return new QueueChannel();
     }
  
     @Bean
-    DirectChannel remainderIs2Channel() {
+    QueueChannel remainderIsTwoChannel() {
-        return new DirectChannel();
+        return new QueueChannel();
+    }
+
+    boolean isMultipleOfThree(Integer number) {
+        return number % 3 == 0;
+    }
+
+    boolean isRemainderOne(Integer number) {
+        return number % 3 == 1;
+    }
+
+    boolean isRemainderTwo(Integer number) {
+        return number % 3 == 2;
     }
 
     @Bean
-    public IntegrationFlow multipleof3Flow() {
+    public IntegrationFlow multipleOfThreeFlow() {
-        return f -> f.split()
+        return flow -> flow.split()
-            .<Integer> filter(p -> p % 3 == 0)
+            .<Integer> filter(this::isMultipleOfThree)
-            .channel("multipleof3Channel");
+            .channel("multipleOfThreeChannel");
     }
 
     @Bean
-    public IntegrationFlow remainderIs1Flow() {
+    public IntegrationFlow remainderIsOneFlow() {
-        return f -> f.split()
+        return flow -> flow.split()
-            .<Integer> filter(p -> p % 3 == 1)
+            .<Integer> filter(this::isRemainderOne)
-            .channel("remainderIs1Channel");
+            .channel("remainderIsOneChannel");
     }
 
     @Bean
-    public IntegrationFlow remainderIs2Flow() {
+    public IntegrationFlow remainderIsTwoFlow() {
-        return f -> f.split()
+        return flow -> flow.split()
-            .<Integer> filter(p -> p % 3 == 2)
+            .<Integer> filter(this::isRemainderTwo)
-            .channel("remainderIs2Channel");
+            .channel("remainderIsTwoChannel");
     }
 
-    public static void main(String[] args) {
-        final ConfigurableApplicationContext ctx = new AnnotationConfigApplicationContext(SeparateFlowsExample.class);
-        DirectChannel multipleof3Channel = ctx.getBean("multipleof3Channel", DirectChannel.class);
-        multipleof3Channel.subscribe(x -> System.out.println("multipleof3Channel: " + x));
-        DirectChannel remainderIs1Channel = ctx.getBean("remainderIs1Channel", DirectChannel.class);
-        remainderIs1Channel.subscribe(x -> System.out.println("remainderIs1Channel: " + x));
-        DirectChannel remainderIs2Channel = ctx.getBean("remainderIs2Channel", DirectChannel.class);
-        remainderIs2Channel.subscribe(x -> System.out.println("remainderIs2Channel: " + x));
-        ctx.getBean(NumbersClassifier.class)
-            .multipleof3(Arrays.asList(1, 2, 3, 4, 5, 6));
-        ctx.getBean(NumbersClassifier.class)
-            .remainderIs1(Arrays.asList(1, 2, 3, 4, 5, 6));
-        ctx.getBean(NumbersClassifier.class)
-            .remainderIs2(Arrays.asList(1, 2, 3, 4, 5, 6));
-        ctx.close();
-    }
 }

spring-integration/src/main/java/com/baeldung/subflows/subflowchannel/FilterExample.java

@@ -1,60 +0,0 @@
-package com.baeldung.subflows.subflowchannel;
-
-import java.util.Arrays;
-import java.util.Collection;
-
-import org.springframework.context.ConfigurableApplicationContext;
-import org.springframework.context.annotation.AnnotationConfigApplicationContext;
-import org.springframework.context.annotation.Bean;
-import org.springframework.integration.annotation.Gateway;
-import org.springframework.integration.annotation.IntegrationComponentScan;
-import org.springframework.integration.annotation.MessagingGateway;
-import org.springframework.integration.channel.DirectChannel;
-import org.springframework.integration.config.EnableIntegration;
-import org.springframework.integration.dsl.IntegrationFlow;
-
-@EnableIntegration
-@IntegrationComponentScan
-public class FilterExample {
-    @MessagingGateway
-    public interface NumbersClassifier {
-        @Gateway(requestChannel = "flow.input")
-        void flow(Collection<Integer> numbers);
-    }
-
-    @Bean
-    DirectChannel multipleof3Channel() {
-        return new DirectChannel();
-    }
-
-    @Bean
-    DirectChannel remainderIs1Channel() {
-        return new DirectChannel();
-    }
-
-    @Bean
-    DirectChannel remainderIs2Channel() {
-        return new DirectChannel();
-    }
-
-    @Bean
-    public IntegrationFlow flow() {
-        return flow -> flow.split()
-            .<Integer> filter(x -> x % 3 == 0, sf -> sf.discardFlow(subf -> subf.<Integer> filter(x -> x % 3 == 1, ssf -> ssf.discardChannel("remainderIs2Channel"))
-                .channel("remainderIs1Channel")))
-            .channel("multipleof3Channel");
-    }
-
-    public static void main(String[] args) {
-        final ConfigurableApplicationContext ctx = new AnnotationConfigApplicationContext(FilterExample.class);
-        DirectChannel multipleof3Channel = ctx.getBean("multipleof3Channel", DirectChannel.class);
-        multipleof3Channel.subscribe(x -> System.out.println("multipleof3Channel: " + x));
-        DirectChannel remainderIs1Channel = ctx.getBean("remainderIs1Channel", DirectChannel.class);
-        remainderIs1Channel.subscribe(x -> System.out.println("remainderIs1Channel: " + x));
-        DirectChannel remainderIs2Channel = ctx.getBean("remainderIs2Channel", DirectChannel.class);
-        remainderIs2Channel.subscribe(x -> System.out.println("remainderIs2Channel: " + x));
-        ctx.getBean(NumbersClassifier.class)
-            .flow(Arrays.asList(1, 2, 3, 4, 5, 6));
-        ctx.close();
-    }
-}

spring-integration/src/main/java/com/baeldung/subflows/subflowmapping/RouterExample.java

@@ -1,15 +1,11 @@
 package com.baeldung.subflows.subflowmapping;
 
-import java.util.Arrays;
 import java.util.Collection;
-
-import org.springframework.context.ConfigurableApplicationContext;
-import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.integration.annotation.Gateway;
 import org.springframework.integration.annotation.IntegrationComponentScan;
 import org.springframework.integration.annotation.MessagingGateway;
-import org.springframework.integration.channel.DirectChannel;
+import org.springframework.integration.channel.QueueChannel;
 import org.springframework.integration.config.EnableIntegration;
 import org.springframework.integration.dsl.IntegrationFlow;
 
@@ -18,44 +14,49 @@ import org.springframework.integration.dsl.IntegrationFlow;
 public class RouterExample {
     @MessagingGateway
     public interface NumbersClassifier {
-        @Gateway(requestChannel = "flow.input")
+        @Gateway(requestChannel = "classify.input")
-        void flow(Collection<Integer> numbers);
+        void classify(Collection<Integer> numbers);
     }
 
     @Bean
-    DirectChannel multipleof3Channel() {
+    QueueChannel multipleofThreeChannel() {
-        return new DirectChannel();
+        return new QueueChannel();
     }
 
     @Bean
-    DirectChannel remainderIs1Channel() {
+    QueueChannel remainderIsOneChannel() {
-        return new DirectChannel();
+        return new QueueChannel();
     }
 
     @Bean
-    DirectChannel remainderIs2Channel() {
+    QueueChannel remainderIsTwoChannel() {
-        return new DirectChannel();
+        return new QueueChannel();
+    }
+
+    boolean isMultipleOfThree(Integer number) {
+        return number % 3 == 0;
+    }
+
+    boolean isRemainderOne(Integer number) {
+        return number % 3 == 1;
+    }
+
+    boolean isRemainderTwo(Integer number) {
+        return number % 3 == 2;
     }
 
     @Bean
-    public IntegrationFlow flow() {
+    public IntegrationFlow classify() {
-        return f -> f.split()
+        return flow -> flow.split()
-            .<Integer, Integer> route(p -> p % 3, m -> m.channelMapping(0, "multipleof3Channel")
+            .<Integer, Integer> route(number -> number % 3, 
-                .subFlowMapping(1, sf -> sf.channel("remainderIs1Channel"))
+                mapping -> mapping
-                .subFlowMapping(2, sf -> sf.<Integer> handle((p, h) -> p)))
+                  .channelMapping(0, "multipleofThreeChannel")
-            .channel("remainderIs2Channel");
+                  .subFlowMapping(1, subflow -> subflow.channel("remainderIsOneChannel"))
+                  .subFlowMapping(2, subflow -> subflow
+                      .<Integer> handle((payload, headers) -> {
+                          // do extra work on the payload
+                         return payload;
+                      }))).channel("remainderIsTwoChannel");
     }
 
-    public static void main(String[] args) {
-        final ConfigurableApplicationContext ctx = new AnnotationConfigApplicationContext(RouterExample.class);
-        DirectChannel multipleof3Channel = ctx.getBean("multipleof3Channel", DirectChannel.class);
-        multipleof3Channel.subscribe(x -> System.out.println("multipleof3Channel: " + x));
-        DirectChannel remainderIs1Channel = ctx.getBean("remainderIs1Channel", DirectChannel.class);
-        remainderIs1Channel.subscribe(x -> System.out.println("remainderIs1Channel: " + x));
-        DirectChannel remainderIs2Channel = ctx.getBean("remainderIs2Channel", DirectChannel.class);
-        remainderIs2Channel.subscribe(x -> System.out.println("remainderIs2Channel: " + x));
-        ctx.getBean(NumbersClassifier.class)
-            .flow(Arrays.asList(1, 2, 3, 4, 5, 6));
-        ctx.close();
-    }
 }

spring-integration/src/test/java/com/baeldung/subflows/discardflow/FilterUnitTest.java

@@ -0,0 +1,62 @@
+package com.baeldung.subflows.discardflow;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Arrays;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.integration.channel.QueueChannel;
+import org.springframework.messaging.Message;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+import com.baeldung.subflows.discardflow.FilterExample.NumbersClassifier;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes = { FilterExample.class })
+public class FilterUnitTest {
+    @Autowired
+    private QueueChannel multipleofThreeChannel;
+
+    @Autowired
+    private QueueChannel remainderIsOneChannel;
+
+    @Autowired
+    private QueueChannel remainderIsTwoChannel;
+
+    @Autowired
+    private NumbersClassifier numbersClassifier;
+
+    @Test
+    public void whenSendMessagesToFlow_thenNumbersAreClassified() {
+
+        numbersClassifier.classify(Arrays.asList(1, 2, 3, 4, 5, 6));
+
+        Message<?> outMessage = multipleofThreeChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 3);
+
+        outMessage = multipleofThreeChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 6);
+
+        outMessage = remainderIsOneChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 1);
+        outMessage = remainderIsOneChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 4);
+
+        outMessage = remainderIsTwoChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 2);
+
+        outMessage = remainderIsTwoChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 5);
+
+    }
+
+}

spring-integration/src/test/java/com/baeldung/subflows/publishsubscribechannel/PublishSubscribeChannelUnitTest.java

@@ -0,0 +1,62 @@
+package com.baeldung.subflows.publishsubscribechannel;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Arrays;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.integration.channel.QueueChannel;
+import org.springframework.messaging.Message;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+import com.baeldung.subflows.publishsubscribechannel.PublishSubscibeChannelExample.NumbersClassifier;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes = { PublishSubscibeChannelExample.class })
+public class PublishSubscribeChannelUnitTest {
+    @Autowired
+    private QueueChannel multipleofThreeChannel;
+
+    @Autowired
+    private QueueChannel remainderIsOneChannel;
+
+    @Autowired
+    private QueueChannel remainderIsTwoChannel;
+
+    @Autowired
+    private NumbersClassifier numbersClassifier;
+
+    @Test
+    public void whenSendMessagesToFlow_thenNumbersAreClassified() {
+
+        numbersClassifier.classify(Arrays.asList(1, 2, 3, 4, 5, 6));
+       
+        Message<?> outMessage = multipleofThreeChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 3);
+
+        outMessage = multipleofThreeChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 6);
+       
+        outMessage = remainderIsOneChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 1);
+        outMessage = remainderIsOneChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 4);
+      
+        outMessage = remainderIsTwoChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 2);
+
+        outMessage = remainderIsTwoChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 5);
+
+    }
+
+}

spring-integration/src/test/java/com/baeldung/subflows/routetorecipients/RouteToRecipientsUnitTest.java

@@ -0,0 +1,63 @@
+package com.baeldung.subflows.routetorecipients;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Arrays;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.integration.channel.QueueChannel;
+import org.springframework.messaging.Message;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+import com.baeldung.subflows.routetorecipients.RouteToRecipientsExample;
+import com.baeldung.subflows.routetorecipients.RouteToRecipientsExample.NumbersClassifier;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes = { RouteToRecipientsExample.class })
+public class RouteToRecipientsUnitTest {
+    @Autowired
+    private QueueChannel multipleofThreeChannel;
+
+    @Autowired
+    private QueueChannel remainderIsOneChannel;
+
+    @Autowired
+    private QueueChannel remainderIsTwoChannel;
+
+    @Autowired
+    private NumbersClassifier numbersClassifier;
+
+    @Test
+    public void whenSendMessagesToFlow_thenNumbersAreClassified() {
+
+        numbersClassifier.classify(Arrays.asList(1, 2, 3, 4, 5, 6));
+
+        Message<?> outMessage = multipleofThreeChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 3);
+
+        outMessage = multipleofThreeChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 6);
+
+        outMessage = remainderIsOneChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 1);
+        outMessage = remainderIsOneChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 4);
+
+        outMessage = remainderIsTwoChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 2);
+
+        outMessage = remainderIsTwoChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 5);
+
+    }
+
+}

spring-integration/src/test/java/com/baeldung/subflows/separateflows/SeparateFlowsUnitTest.java

@@ -0,0 +1,75 @@
+package com.baeldung.subflows.separateflows;
+
+import java.util.Arrays;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.integration.channel.QueueChannel;
+import org.springframework.messaging.Message;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import com.baeldung.subflows.separateflows.SeparateFlowsExample.NumbersClassifier;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes = { SeparateFlowsExample.class })
+public class SeparateFlowsUnitTest {
+    @Autowired
+    private QueueChannel multipleOfThreeChannel;
+    @Autowired
+    private QueueChannel remainderIsOneChannel;
+    @Autowired
+    private QueueChannel remainderIsTwoChannel;
+
+    @Autowired
+    private NumbersClassifier numbersClassifier;
+
+    @Test
+    public void whenSendMessagesToMultipleOf3Flow_thenOutputMultiplesOf3() {
+
+        numbersClassifier.multipleofThree(Arrays.asList(1, 2, 3, 4, 5, 6));
+
+        Message<?> outMessage = multipleOfThreeChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 3);
+
+        outMessage = multipleOfThreeChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 6);
+        outMessage = multipleOfThreeChannel.receive(0);
+        assertNull(outMessage);
+    }
+
+    @Test
+    public void whenSendMessagesToRemainderIs1Flow_thenOutputRemainderIs1() {
+
+        numbersClassifier.remainderIsOne(Arrays.asList(1, 2, 3, 4, 5, 6));
+
+        Message<?> outMessage = remainderIsOneChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 1);
+
+        outMessage = remainderIsOneChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 4);
+
+    }
+
+    @Test
+    public void whenSendMessagesToRemainderIs2Flow_thenOutputRemainderIs2() {
+
+        numbersClassifier.remainderIsTwo(Arrays.asList(1, 2, 3, 4, 5, 6));
+
+        Message<?> outMessage = remainderIsTwoChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 2);
+
+        outMessage = remainderIsTwoChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 5);
+
+    }
+
+}

spring-integration/src/test/java/com/baeldung/subflows/subflowmapping/RouterUnitTest.java

@@ -0,0 +1,62 @@
+package com.baeldung.subflows.subflowmapping;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Arrays;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.integration.channel.QueueChannel;
+import org.springframework.messaging.Message;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+import com.baeldung.subflows.subflowmapping.RouterExample.NumbersClassifier;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes = { RouterExample.class })
+public class RouterUnitTest {
+    @Autowired
+    private QueueChannel multipleofThreeChannel;
+
+    @Autowired
+    private QueueChannel remainderIsOneChannel;
+
+    @Autowired
+    private QueueChannel remainderIsTwoChannel;
+
+    @Autowired
+    private NumbersClassifier numbersClassifier;
+
+    @Test
+    public void whenSendMessagesToFlow_thenNumbersAreClassified() {
+
+        numbersClassifier.classify(Arrays.asList(1, 2, 3, 4, 5, 6));
+
+        Message<?> outMessage = multipleofThreeChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 3);
+
+        outMessage = multipleofThreeChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 6);
+
+        outMessage = remainderIsOneChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 1);
+        outMessage = remainderIsOneChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 4);
+
+        outMessage = remainderIsTwoChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 2);
+
+        outMessage = remainderIsTwoChannel.receive(0);
+
+        assertEquals(outMessage.getPayload(), 5);
+
+    }
+
+}