BAEL-1790 Spring Integration Java DSL Tutorlal

spring-integration/src/main/java/com/baeldung/dsl/JavaDSLFileCopyConfig.java

@@ -0,0 +1,146 @@
+package com.baeldung.dsl;
+
+import java.io.File;
+import java.util.Scanner;
+import java.util.concurrent.TimeUnit;
+
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.support.AbstractApplicationContext;
+import org.springframework.integration.annotation.IntegrationComponentScan;
+import org.springframework.integration.channel.PriorityChannel;
+import org.springframework.integration.config.EnableIntegration;
+import org.springframework.integration.core.GenericSelector;
+import org.springframework.integration.core.MessageSource;
+import org.springframework.integration.dsl.IntegrationFlow;
+import org.springframework.integration.dsl.IntegrationFlows;
+import org.springframework.integration.dsl.Pollers;
+import org.springframework.integration.file.FileReadingMessageSource;
+import org.springframework.integration.file.FileWritingMessageHandler;
+import org.springframework.messaging.MessageHandler;
+
+/**
+ * JavaDSLFileCopyConfig contains various Integration Flows created from various spring integration components.
+ * Activate only one flow at a time by un-commenting @Bean annotation from IntegrationFlow beans. 
+ * <p>
+ * Different flows are :<br>
+ * - {@link #fileMover()} - default app - activated<br>
+ * - {@link #fileMoverWithLambda()} - app with file writing expressions as lambda<br>
+ * - {@link #fileMoverWithPriorityChannel()} - app with priority channel<br>
+ * - {@link #fileReader()}, {@link #fileWriter()}, {@link #anotherFileWriter()} - app with bridge
+ */
+@Configuration
+@EnableIntegration
+@IntegrationComponentScan
+public class JavaDSLFileCopyConfig {
+
+    public static final String INPUT_DIR = "source";
+    public static final String OUTPUT_DIR = "target";
+    public static final String OUTPUT_DIR2 = "target2";
+
+    @Bean
+    public MessageSource<File> sourceDirectory() {
+        FileReadingMessageSource messageSource = new FileReadingMessageSource();
+        messageSource.setDirectory(new File(INPUT_DIR));
+        return messageSource;
+    }
+
+    @Bean
+    public GenericSelector<File> onlyJpgs() {
+        return new GenericSelector<File>() {
+
+            @Override
+            public boolean accept(File source) {
+              return source.getName()
+                .endsWith(".jpg");
+            }
+        };
+    }
+
+    @Bean
+    public MessageHandler targetDirectory() {
+        FileWritingMessageHandler handler = new FileWritingMessageHandler(new File(OUTPUT_DIR));
+        handler.setExpectReply(false); // end of pipeline, reply not needed
+        return handler;
+    }
+    
+    @Bean
+    public IntegrationFlow fileMover() {
+        return IntegrationFlows.from(sourceDirectory(), configurer -> configurer.poller(Pollers.fixedDelay(10000)))
+            .filter(onlyJpgs())
+            .handle(targetDirectory())
+            .get();
+    }
+
+    // @Bean
+    public IntegrationFlow fileMoverWithLambda() {
+        return IntegrationFlows.from(sourceDirectory(), configurer -> configurer.poller(Pollers.fixedDelay(10000)))
+            .filter(message -> ((File) message).getName()
+                .endsWith(".jpg"))
+            .handle(targetDirectory())
+            .get();
+    }
+
+    @Bean
+    public PriorityChannel alphabetically() {
+        return new PriorityChannel(1000, (left, right) -> ((File) left.getPayload()).getName()
+            .compareTo(((File) right.getPayload()).getName()));
+    }
+
+    // @Bean
+    public IntegrationFlow fileMoverWithPriorityChannel() {
+        return IntegrationFlows.from(sourceDirectory())
+            .filter(onlyJpgs())
+            .channel("alphabetically")
+            .handle(targetDirectory())
+            .get();
+    }
+
+    @Bean
+    public MessageHandler anotherTargetDirectory() {
+        FileWritingMessageHandler handler = new FileWritingMessageHandler(new File(OUTPUT_DIR2));
+        handler.setExpectReply(false); // end of pipeline, reply not needed
+        return handler;
+    }
+
+    // @Bean
+    public IntegrationFlow fileReader() {
+        return IntegrationFlows.from(sourceDirectory())
+            .filter(onlyJpgs())
+            .channel("holdingTank")
+            .get();
+    }
+
+    // @Bean
+    public IntegrationFlow fileWriter() {
+        return IntegrationFlows.from("holdingTank")
+            .bridge(e -> e.poller(Pollers.fixedRate(1, TimeUnit.SECONDS, 20)))
+            .handle(targetDirectory())
+            .get();
+    }
+
+    // @Bean
+    public IntegrationFlow anotherFileWriter() {
+        return IntegrationFlows.from("holdingTank")
+            .bridge(e -> e.poller(Pollers.fixedRate(2, TimeUnit.SECONDS, 10)))
+            .handle(anotherTargetDirectory())
+            .get();
+    }
+
+    public static void main(final String... args) {
+        final AbstractApplicationContext context = new AnnotationConfigApplicationContext(JavaDSLFileCopyConfig.class);
+        context.registerShutdownHook();
+        final Scanner scanner = new Scanner(System.in);
+        System.out.print("Please enter a string and press <enter>: ");
+        while (true) {
+            final String input = scanner.nextLine();
+            if ("q".equals(input.trim())) {
+                context.close();
+                scanner.close();
+                break;
+            }
+        }
+        System.exit(0);
+    }
+}