Order annotation in Spring

spring-core-order-annotation/pom.xml

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+<?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">
+    <parent>
+        <artifactId>spring-framework-tutorial-parent</artifactId>
+        <groupId>com.jstobigdata</groupId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>spring-core-order-annotation</artifactId>
+    <description>Use of Spring's @Order annotation</description>
+    <dependencies>
+
+        <!-- Step-1 Add the dependencies -->
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-core</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-context</artifactId>
+        </dependency>
+
+        <!-- Test Dependencies-->
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>com.jstobigdata</groupId>
+                <artifactId>spring-tutorial-boms</artifactId>
+                <type>pom</type>
+                <scope>import</scope>
+                <version>1.0-SNAPSHOT</version>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
+    <!-- For Junit-jupiter-->
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>3.0.0-M3</version>
+            </plugin>
+        </plugins>
+    </build>
+</project>

spring-core-order-annotation/src/main/java/com/jsbd/order/ApplicationConfig.java

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+package com.jsbd.order;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.annotation.Order;
+
+import com.jsbd.order.model.NotificationChannel;
+
+@Configuration
+@ComponentScan("com.jsbd.order")
+public class ApplicationConfig {
+
+
+    @Bean
+    @Order(2)
+    public NotificationChannel email(){
+        // System.out.println("Notification Channel - Email");
+        return new NotificationChannel("Email");
+    }
+
+    @Bean
+    @Order(4)
+    public NotificationChannel twitter(){
+        // System.out.println("Notification Channel - Twitter");
+        return new NotificationChannel("Twitter");
+    }
+
+    @Bean
+    @Order(3)
+    public NotificationChannel slack(){
+        // System.out.println("Notification Channel - Slack");
+        return new NotificationChannel("Slack");
+    }
+
+    @Bean
+    @Order(1)
+    public NotificationChannel sms(){
+        // System.out.println("Notification Channel - Sms");
+        return new NotificationChannel("Sms");
+    }
+
+}

spring-core-order-annotation/src/main/java/com/jsbd/order/model/NotificationChannel.java

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+package com.jsbd.order.model;
+
+public class NotificationChannel {
+
+    private String name;
+
+    public NotificationChannel(String channelName) {
+        this.name = channelName;
+    }
+
+    public String getName() {
+        return name;
+    }
+}

spring-core-order-annotation/src/main/java/com/jsbd/order/service/EmailNotification.java

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+package com.jsbd.order.service;
+
+import org.springframework.core.annotation.Order;
+import org.springframework.stereotype.Service;
+
+@Service
+@Order(3)
+public class EmailNotification implements NotificationHandler {
+
+    public EmailNotification() {
+        System.out.println("EmailNotification Service Created.");
+    }
+
+    @Override
+    public void send() {
+        System.out.println("Email Notification Handler");
+    }
+
+}

spring-core-order-annotation/src/main/java/com/jsbd/order/service/NotificationHandler.java

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+package com.jsbd.order.service;
+
+public interface NotificationHandler {
+    void send();
+}

spring-core-order-annotation/src/main/java/com/jsbd/order/service/SlackNotification.java

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+package com.jsbd.order.service;
+
+import org.springframework.core.annotation.Order;
+import org.springframework.stereotype.Service;
+
+@Service
+@Order(2)
+class SlackNotification implements NotificationHandler {
+
+    public SlackNotification() {
+        System.out.println("SlackNotification Service created.");
+    }
+
+    @Override
+    public void send() {
+        System.out.println("Slack Notification Handler");
+    }
+
+}

spring-core-order-annotation/src/main/java/com/jsbd/order/service/SmsNotification.java

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+package com.jsbd.order.service;
+
+import org.springframework.core.annotation.Order;
+import org.springframework.stereotype.Service;
+
+@Service
+@Order(1)
+class SmsNotification implements NotificationHandler {
+
+    public SmsNotification() {
+        System.out.println("SmsNotification Service created.");
+    }
+
+    @Override
+    public void send() {
+        System.out.println("SMS Notification Handler");
+    }
+
+}

spring-core-order-annotation/src/main/java/com/jsbd/order/service/TwitterNotification.java

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+package com.jsbd.order.service;
+
+import org.springframework.stereotype.Service;
+
+@Service
+// Not an Ordered Service, will be the last in sequence
+class TwitterNotification implements NotificationHandler {
+
+    public TwitterNotification() {
+        System.out.println("TwitterNotification Service created.");
+    }
+
+    @Override
+    public void send() {
+        System.out.println("Twitter Direct Message Notification Handler");
+    }
+
+}

spring-core-order-annotation/src/test/java/com/jsbd/order/TestOrderOnCollectionInjection.java

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+package com.jsbd.order;
+
+import java.util.List;
+
+import com.jsbd.order.model.NotificationChannel;
+import com.jsbd.order.service.NotificationHandler;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+
+@SpringJUnitConfig(ApplicationConfig.class)
+public class TestOrderOnCollectionInjection {
+
+  @Autowired
+  private List<NotificationHandler> notificationHandlers;
+
+  @Autowired
+  private List<NotificationChannel> notificationChannels;
+
+  @Test
+  public void testAllChannelSendingOrder() {
+    notificationHandlers.forEach(NotificationHandler::send);
+  }
+
+  @Test
+  public void testNotificationChannelBeanOrder(){
+    notificationChannels.forEach(channel -> System.out.println(channel.getName()));
+  }
+
+}