Merge pull request #9888 from azhwani/BAEL-4244

BAEL-4244: What is purpose of @ConditionalOnProperty annotation?

spring-boot-modules/spring-boot-autoconfiguration/src/main/java/com/baeldung/conditionalonproperty/NotificationApplication.java

@@ -0,0 +1,12 @@
+package com.baeldung.conditionalonproperty;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class NotificationApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(NotificationApplication.class, args);
+    }
+}

spring-boot-modules/spring-boot-autoconfiguration/src/main/java/com/baeldung/conditionalonproperty/config/NotificationConfig.java

@@ -0,0 +1,26 @@
+package com.baeldung.conditionalonproperty.config;
+
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import com.baeldung.conditionalonproperty.service.EmailNotification;
+import com.baeldung.conditionalonproperty.service.NotificationSender;
+import com.baeldung.conditionalonproperty.service.SmsNotification;
+
+@Configuration
+public class NotificationConfig {
+
+    @Bean(name = "emailNotification")
+    @ConditionalOnProperty(prefix = "notification", name = "service", havingValue = "email")
+    public NotificationSender notificationSender() {
+        return new EmailNotification();
+    }
+
+    @Bean(name = "smsNotification")
+    @ConditionalOnProperty(prefix = "notification", name = "service", havingValue = "sms")
+    public NotificationSender notificationSender2() {
+        return new SmsNotification();
+    }
+
+}

spring-boot-modules/spring-boot-autoconfiguration/src/main/java/com/baeldung/conditionalonproperty/service/EmailNotification.java

@@ -0,0 +1,10 @@
+package com.baeldung.conditionalonproperty.service;
+
+public class EmailNotification implements NotificationSender {
+
+    @Override
+    public String send(String message) {
+        return "Email Notification: " + message;
+    }
+
+}

spring-boot-modules/spring-boot-autoconfiguration/src/main/java/com/baeldung/conditionalonproperty/service/NotificationSender.java

@@ -0,0 +1,5 @@
+package com.baeldung.conditionalonproperty.service;
+
+public interface NotificationSender {
+    String send(String message);
+}

spring-boot-modules/spring-boot-autoconfiguration/src/main/java/com/baeldung/conditionalonproperty/service/SmsNotification.java

@@ -0,0 +1,10 @@
+package com.baeldung.conditionalonproperty.service;
+
+public class SmsNotification implements NotificationSender {
+
+    @Override
+    public String send(String message) {
+        return "SMS notification: " + message;
+    }
+
+}

spring-boot-modules/spring-boot-autoconfiguration/src/main/resources/application.properties

@@ -1,2 +1,4 @@
 spring.jpa.show-sql=true
 spring.jpa.hibernate.ddl-auto = update
+
+notification.service=email

spring-boot-modules/spring-boot-autoconfiguration/src/test/java/com/baeldung/conditionalonproperty/NotificationUnitTest.java

@@ -0,0 +1,27 @@
+package com.baeldung.conditionalonproperty;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+
+import com.baeldung.conditionalonproperty.config.NotificationConfig;
+import com.baeldung.conditionalonproperty.service.EmailNotification;
+import com.baeldung.conditionalonproperty.service.NotificationSender;
+
+public class NotificationUnitTest {
+
+    private final ApplicationContextRunner contextRunner = new ApplicationContextRunner();
+
+    @Test
+    public void whenValueSetToEmail_thenCreateEmailNotification() {
+        this.contextRunner.withPropertyValues("notification.service=email")
+            .withUserConfiguration(NotificationConfig.class)
+            .run(context -> {
+                assertThat(context).hasBean("emailNotification");
+                NotificationSender notificationSender = context.getBean(EmailNotification.class);
+                assertThat(notificationSender.send("Hello From Baeldung!")).isEqualTo("Email Notification: Hello From Baeldung!");
+                assertThat(context).doesNotHaveBean("smsNotification");
+            });
+    }
+}