In this article, we will explore top 16 Spring Boot Annotations which every developer should know. So, let’s get started.
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
@EnableConfigurationProperties
: Enables the automatic resolution of@ConfigurationProperties
beans.
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:
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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