Top 16 Spring Boot Annotations(2023)

In this article, we will explore top 16 Spring Boot Annotations which every developer should know. So, let’s get started.

Spring Boot Annotations

Core Spring Boot Annotations

  • @SpringBootApplication: This annotation marks a class as a Spring Boot application. It combines @Configuration, @EnableAutoConfiguration, and @ComponentScan.

Read More : @SpringBootApplication Annotation

  • @EnableAutoConfiguration: Enables automatic configuration of Spring Boot based on project dependencies.

Read More : Spring Boot : Auto Configuration

Auto-Configuration Conditions Annotations

These annotations are used to conditionally enable or disable auto-configuration based on specific conditions.

  • @ConditionalOnClass: Specifies that a bean should be created only if a specified class is present on the classpath.
  • @ConditionalOnMissingClass: Specifies that a bean should be created only if a specified class is missing from the classpath.
  • @ConditionalOnBean: Specifies that a bean should only be created if another bean of a specific type is already present in the application context.
  • @ConditionalOnMissingBean: Specifies that a bean should only be created if another bean of a specific type is not already present in the application context.
  • @ConditionalOnProperty: Allows you to enable or disable components or configurations based on the values of properties in the configuration files.
  • @ConditionalOnResource: Specifies that a bean should only be created if a certain resource is present.
  • @ConditionalOnWebApplication: Specifies that a bean should only be created if the application is a web application.
  • @ConditionalOnNotWebApplication: Similar to @ConditionalOnWebApplication, but creates components when the application is not a web application.
  • @ConditionalOnExpression: Allows you to conditionally create a bean based on a SpEL (Spring Expression Language) expression.
  • @ConditionalOnJava: Specifies that a bean should be created based on the Java version.

Read More : Top 10 Spring Boot Conditional Annotations

Spring Boot Annotations : Configuration Properties

These annotations are used for configuring properties.

  • @ConfigurationProperties: Used to bind external configuration properties to a Spring Boot bean.

Read More : @ConfigurationProperties

Testing Annotations

These annotations are commonly used for testing Spring Boot applications.

  • @SpringBootTest: Used for integration testing, it specifies how to load the Spring ApplicationContext.
  • @MockBean: In testing, it allows you to mock a bean when using @SpringBootTest.
  • @DataJpaTest: Used for JPA repository tests, it configures an in-memory database and scans for relevant JPA components.
  • @WebMvcTest: For testing the Spring MVC layer, it configures a limited Spring ApplicationContext.

Here’s a simple Java code example that demonstrates the use of these Spring Boot testing annotations:

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.boot.test.context.SpringBootTest;

// Import other necessary dependencies and classes as needed

public class MyIntegrationTest {

    private MyService myService; // Inject a real bean

    private MyMockedService mockedService; // Mock a bean

    public void testIntegrationWithRealAndMockedBeans() {
        // Your integration test logic here
        // You can use both real and mocked beans in this test

public class MyJpaRepositoryTest {

    private MyJpaRepository jpaRepository; // Auto-configured JPA repository

    public void testJpaRepository() {
        // Your JPA repository test logic here
        // Spring Boot configures an in-memory database for this test

public class MyWebMvcTest {

    private MockMvc mockMvc; // Mocked Spring MVC environment

    public void testController() throws Exception {
        // Your Spring MVC controller test logic here
        // Spring Boot configures a limited Spring ApplicationContext for this test

Conclusion: Spring Boot Annotations

This article has provided a comprehensive overview of the top 16 Spring Boot annotations that every developer should be familiar with. These annotations play a pivotal role in configuring, customizing, and optimizing Spring Boot applications.

We explored core Spring Boot annotations like @SpringBootApplication and @EnableAutoConfiguration, which are fundamental in setting up a Spring Boot application. Additionally, we delved into conditional annotations such as @ConditionalOnClass, @ConditionalOnBean, and @ConditionalOnProperty, which allow developers to fine-tune the auto-configuration of their applications based on specific conditions.

The article also covered annotations related to configuration properties, such as @ConfigurationProperties and @EnableConfigurationProperties, which are crucial for binding external configuration properties to Spring Boot beans.

Lastly, we discussed testing annotations like @SpringBootTest, @MockBean, @DataJpaTest, and @WebMvcTest, which simplify the process of testing Spring Boot applications.

Understanding and effectively utilizing these Spring Boot annotations empowers developers to build robust, configurable, and well-tested applications in a streamlined manner.

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