Add Kafka sample

See gh-11597

spring-boot-samples/README.adoc

@@ -230,3 +230,6 @@ The following sample applications are provided:
 | link:spring-boot-sample-xml[spring-boot-sample-xml]
 | Example show how Spring Boot can be mixed with traditional XML configuration (we
   generally recommend using Java `@Configuration` whenever possible
+  
+| link:spring-boot-sample-kafka[spring-boot-sample-kafka]
+| consumer and producer using Apache Kafka

spring-boot-samples/pom.xml

@@ -97,6 +97,7 @@
 		<module>spring-boot-sample-websocket-undertow</module>
 		<module>spring-boot-sample-webservices</module>
 		<module>spring-boot-sample-xml</module>
+		<module>spring-boot-sample-kafka</module>
 	</modules>
 	<!-- No dependencies - otherwise the samples won't work if you change the
 		parent -->

spring-boot-samples/spring-boot-sample-kafka/pom.xml

@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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>
+	<parent>
+		<!-- Your own application should inherit from spring-boot-starter-parent -->
+		<artifactId>spring-boot-samples</artifactId>
+		<groupId>org.springframework.boot</groupId>
+		<version>${revision}</version>
+	</parent>
+	<artifactId>spring-boot-sample-kafka</artifactId>
+	<name>Spring Boot Kafka Sample</name>
+	<description>Spring Boot Kafka Sample</description>
+
+	<properties>
+		<main.basedir>${basedir}/../..</main.basedir>
+	</properties>
+
+	<dependencies>
+		<!-- Compile -->
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.kafka</groupId>
+			<artifactId>spring-kafka</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-json</artifactId>
+		</dependency>
+		<!-- Test -->
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-test</artifactId>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.kafka</groupId>
+			<artifactId>spring-kafka-test</artifactId>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.boot</groupId>
+				<artifactId>spring-boot-maven-plugin</artifactId>
+			</plugin>
+		</plugins>
+	</build>
+</project>

spring-boot-samples/spring-boot-sample-kafka/src/main/java/sample/kafka/Consumer.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2012-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package sample.kafka;
+
+import org.springframework.kafka.annotation.KafkaListener;
+import org.springframework.stereotype.Component;
+
+@Component
+public class Consumer {
+
+	@KafkaListener(topics = "myTopic")
+	public void processMessage(SampleMessage message) {
+		System.out.println("consumer has received message : [" + message + "]");
+	}
+}

spring-boot-samples/spring-boot-sample-kafka/src/main/java/sample/kafka/Producer.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2012-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package sample.kafka;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.kafka.core.KafkaTemplate;
+import org.springframework.stereotype.Component;
+
+@Component
+public class Producer {
+
+	@Autowired
+	private KafkaTemplate kafkaTemplate;
+
+	public void send(SampleMessage message) {
+		kafkaTemplate.send("myTopic", message);
+		System.out.println("producer has sent message.");
+	}
+}

spring-boot-samples/spring-boot-sample-kafka/src/main/java/sample/kafka/SampleKafkaApplication.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2012-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package sample.kafka;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class SampleKafkaApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(SampleKafkaApplication.class, args);
+	}
+}

spring-boot-samples/spring-boot-sample-kafka/src/main/java/sample/kafka/SampleMessage.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2012-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package sample.kafka;
+
+public class SampleMessage {
+	private Integer id;
+	private String message;
+
+	public Integer getId() {
+		return id;
+	}
+
+	public void setId(Integer id) {
+		this.id = id;
+	}
+
+	public String getMessage() {
+		return message;
+	}
+
+	public void setMessage(String message) {
+		this.message = message;
+	}
+
+	public SampleMessage() {
+	}
+
+	public SampleMessage(Integer id, String message) {
+		this.id = id;
+		this.message = message;
+	}
+
+	@Override
+	public String toString() {
+		return "SampleMessage{" +
+				"id=" + id +
+				", message='" + message + '\'' +
+				'}';
+	}
+}

spring-boot-samples/spring-boot-sample-kafka/src/main/resources/application.properties

@@ -0,0 +1,5 @@
+spring.kafka.bootstrap-servers=localhost:9092
+spring.kafka.consumer.group-id=myGroup
+spring.kafka.consumer.value-deserializer=org.springframework.kafka.support.serializer.JsonDeserializer
+spring.kafka.Producer.value-serializer=org.springframework.kafka.support.serializer.JsonSerializer
+spring.kafka.consumer.properties.spring.json.trusted.packages=sample.kafka

spring-boot-samples/spring-boot-sample-kafka/src/test/java/sample/kafka/SampleKafkaApplicationTests.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2012-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package sample.kafka;
+
+import org.junit.Rule;
+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.boot.test.rule.OutputCapture;
+import org.springframework.kafka.test.rule.KafkaEmbedded;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Integration tests for demo application.
+ *
+ * @author hcxin
+ */
+@RunWith(SpringRunner.class)
+@SpringBootTest
+public class SampleKafkaApplicationTests {
+
+	@Rule
+	public OutputCapture outputCapture = new OutputCapture();
+
+	@Autowired
+	private Producer producer;
+
+	@Test
+	public void sendSimpleMessage() throws Exception {
+		initKafkaEmbedded();
+		SampleMessage message = new SampleMessage(1, "Test message");
+		producer.send(message);
+		Thread.sleep(1000L);
+		assertThat(this.outputCapture.toString().contains("Test message")).isTrue();
+	}
+
+	public void initKafkaEmbedded() throws Exception {
+		KafkaEmbedded embeddedKafka = new KafkaEmbedded(1, true);
+		embeddedKafka.setKafkaPorts(9092);
+		embeddedKafka.afterPropertiesSet();
+		//Need 10s, waiting for the Kafka server start.
+		Thread.sleep(10000L);
+
+	}
+}