added example Spring Boot Starter

thombergs · thombergs · commit 5646e0f169eb · 2019-08-28T21:21:05.000+02:00
diff --git a/spring-boot/starter/application/application.yml b/spring-boot/starter/application/application.yml
@@ -0,0 +1,4 @@
+eventstarter:
+  listener:
+    enabled-events:
+      - foo
diff --git a/spring-boot/starter/application/build.gradle b/spring-boot/starter/application/build.gradle
@@ -0,0 +1,22 @@
+plugins {
+	id 'org.springframework.boot' version '2.1.7.RELEASE'
+	id 'io.spring.dependency-management' version '1.0.8.RELEASE'
+	id 'java'
+}
+
+group = 'io.reflectoring'
+version = '0.0.1-SNAPSHOT'
+sourceCompatibility = '11'
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation project(':event-starter')
+	implementation 'org.springframework.boot:spring-boot-starter-web'
+	testImplementation 'org.springframework.boot:spring-boot-starter-test'
+
+	compileOnly('org.projectlombok:lombok:1.18.2')
+	annotationProcessor 'org.projectlombok:lombok:1.18.2'
+}
diff --git a/spring-boot/starter/application/src/main/java/io/reflectoring/starter/EventGenerator.java b/spring-boot/starter/application/src/main/java/io/reflectoring/starter/EventGenerator.java
@@ -0,0 +1,21 @@
+package io.reflectoring.starter;
+
+import org.springframework.scheduling.annotation.Scheduled;
+import org.springframework.stereotype.Component;
+
+@Component
+class EventGenerator {
+
+	private final EventPublisher eventPublisher;
+
+	public EventGenerator(EventPublisher eventPublisher) {
+		this.eventPublisher = eventPublisher;
+	}
+
+	@Scheduled(fixedRate = 2000)
+	void generateEvent() {
+		Event event = new Event("foo", "This is a foo event");
+		eventPublisher.publishEvent(event);
+	}
+
+}
diff --git a/spring-boot/starter/application/src/main/java/io/reflectoring/starter/FooEventListener.java b/spring-boot/starter/application/src/main/java/io/reflectoring/starter/FooEventListener.java
@@ -0,0 +1,23 @@
+package io.reflectoring.starter;
+
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Component;
+
+@Slf4j
+@Component
+class FooEventListener extends EventListener {
+
+	public FooEventListener(EventListenerProperties properties) {
+		super(properties);
+	}
+
+	@Override
+	public String getSubscribedEventType() {
+		return "foo";
+	}
+
+	@Override
+	public void onEvent(Event event) {
+		log.info("received event {}", event);
+	}
+}
diff --git a/spring-boot/starter/application/src/main/java/io/reflectoring/starter/StarterApplication.java b/spring-boot/starter/application/src/main/java/io/reflectoring/starter/StarterApplication.java
@@ -0,0 +1,15 @@
+package io.reflectoring.starter;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.scheduling.annotation.EnableScheduling;
+
+@SpringBootApplication
+@EnableScheduling
+public class StarterApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(StarterApplication.class, args);
+	}
+
+}
diff --git a/spring-boot/starter/application/src/main/resources/application.properties b/spring-boot/starter/application/src/main/resources/application.properties
@@ -0,0 +1,2 @@
+eventstarter.enabled=true
+event
diff --git a/spring-boot/starter/application/src/test/java/io/reflectoring/starter/StarterApplicationTests.java b/spring-boot/starter/application/src/test/java/io/reflectoring/starter/StarterApplicationTests.java
@@ -0,0 +1,22 @@
+package io.reflectoring.starter;
+
+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;
+import static org.assertj.core.api.Assertions.*;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest
+public class StarterApplicationTests {
+
+	@Autowired(required = false)
+	private EventPublisher eventPublisher;
+
+	@Test
+	public void eventPublisherIsAvailable() {
+		assertThat(eventPublisher).isNotNull();
+	}
+
+}
diff --git a/spring-boot/starter/build.gradle b/spring-boot/starter/build.gradle
diff --git a/spring-boot/starter/event-starter/build.gradle b/spring-boot/starter/event-starter/build.gradle
@@ -0,0 +1,30 @@
+plugins {
+    id 'io.spring.dependency-management' version '1.0.8.RELEASE'
+    id 'java'
+}
+
+group = 'io.reflectoring'
+version = '0.0.1-SNAPSHOT'
+sourceCompatibility = '11'
+
+repositories {
+    mavenCentral()
+}
+
+dependencyManagement {
+    imports {
+        mavenBom("org.springframework.boot:spring-boot-dependencies:2.1.7.RELEASE")
+    }
+}
+
+dependencies {
+    compileOnly 'org.springframework.boot:spring-boot-starter'
+    annotationProcessor 'org.springframework.boot:spring-boot-autoconfigure-processor'
+    annotationProcessor 'org.springframework.boot:spring-boot-configuration-processor'
+    testImplementation 'org.springframework.boot:spring-boot-starter-test'
+
+    compileOnly('org.projectlombok:lombok:1.18.2')
+    annotationProcessor 'org.projectlombok:lombok:1.18.2'
+}
+
+compileJava.dependsOn(processResources)
diff --git a/spring-boot/starter/event-starter/src/main/java/io/reflectoring/starter/Event.java b/spring-boot/starter/event-starter/src/main/java/io/reflectoring/starter/Event.java
@@ -0,0 +1,13 @@
+package io.reflectoring.starter;
+
+import lombok.ToString;
+import lombok.Value;
+
+@Value
+@ToString
+class Event {
+
+	private String type;
+	private String payload;
+
+}
diff --git a/spring-boot/starter/event-starter/src/main/java/io/reflectoring/starter/EventAutoConfiguration.java b/spring-boot/starter/event-starter/src/main/java/io/reflectoring/starter/EventAutoConfiguration.java
@@ -0,0 +1,20 @@
+package io.reflectoring.starter;
+
+import java.util.List;
+
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+@ConditionalOnProperty(value = "eventstarter.enabled", havingValue = "true")
+@EnableConfigurationProperties(EventListenerProperties.class)
+class EventAutoConfiguration {
+
+	@Bean
+	EventPublisher eventPublisher(List<EventListener> listeners){
+		return new EventPublisher(listeners);
+	}
+
+}
diff --git a/spring-boot/starter/event-starter/src/main/java/io/reflectoring/starter/EventListener.java b/spring-boot/starter/event-starter/src/main/java/io/reflectoring/starter/EventListener.java
@@ -0,0 +1,32 @@
+package io.reflectoring.starter;
+
+import lombok.RequiredArgsConstructor;
+
+/**
+ * Interface to be implemented for all event types that the application should react to.
+ * EventListeners will be automatically included when they are part of the application context.
+ */
+@RequiredArgsConstructor
+public abstract class EventListener {
+
+	private final EventListenerProperties properties;
+
+	public void receive(Event event) {
+		if(isEnabled(event) && isSubscribed(event)){
+			onEvent(event);
+		}
+	}
+
+	private boolean isSubscribed(Event event) {
+		return event.getType().equals(getSubscribedEventType());
+	}
+
+	private boolean isEnabled(Event event) {
+		return properties.getEnabledEvents().contains(event.getType());
+	}
+
+	protected abstract String getSubscribedEventType();
+
+	protected abstract void onEvent(Event event);
+
+}
diff --git a/spring-boot/starter/event-starter/src/main/java/io/reflectoring/starter/EventListenerProperties.java b/spring-boot/starter/event-starter/src/main/java/io/reflectoring/starter/EventListenerProperties.java
@@ -0,0 +1,19 @@
+package io.reflectoring.starter;
+
+import java.util.Collections;
+import java.util.List;
+
+import lombok.Data;
+import org.springframework.boot.context.properties.ConfigurationProperties;
+
+@ConfigurationProperties(prefix = "eventstarter.listener")
+@Data
+class EventListenerProperties {
+
+	/**
+	 * List of event types that will be passed to {@link EventListener} implementations. All other events
+	 * will be ignored.
+	 */
+	private List<String> enabledEvents = Collections.emptyList();
+
+}
diff --git a/spring-boot/starter/event-starter/src/main/java/io/reflectoring/starter/EventPublisher.java b/spring-boot/starter/event-starter/src/main/java/io/reflectoring/starter/EventPublisher.java
@@ -0,0 +1,28 @@
+package io.reflectoring.starter;
+
+
+import java.util.List;
+
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * Dummy implementation of an event publisher. Simply publishes an event to all listeners that
+ * are subscribed to that event. This solution obviously doesn't work
+ * across JVM-boundaries... .
+ */
+@Slf4j
+@RequiredArgsConstructor
+public class EventPublisher {
+
+	private final List<EventListener> listeners;
+
+	public void publishEvent(Event event) {
+		log.info("publishing event: {}", event);
+		for (EventListener listener : listeners) {
+			listener.receive(event);
+		}
+	}
+
+
+}
diff --git a/spring-boot/starter/event-starter/src/main/resources/META-INF/spring.factories b/spring-boot/starter/event-starter/src/main/resources/META-INF/spring.factories
@@ -0,0 +1,2 @@
+org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
+  io.reflectoring.starter.EventAutoConfiguration
diff --git a/spring-boot/starter/gradle/wrapper/gradle-wrapper.jar b/spring-boot/starter/gradle/wrapper/gradle-wrapper.jar
diff --git a/spring-boot/starter/gradle/wrapper/gradle-wrapper.properties b/spring-boot/starter/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.6-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
diff --git a/spring-boot/starter/gradlew b/spring-boot/starter/gradlew
diff --git a/spring-boot/starter/gradlew.bat b/spring-boot/starter/gradlew.bat
diff --git a/spring-boot/starter/settings.gradle b/spring-boot/starter/settings.gradle
