Spring Boot Framework and its widely used annotations
Spring Boot is a powerful framework that simplifies the development of Java-based web applications, making it easier and faster to create production-ready applications.
Here are some of the key roles of a Spring Boot application:
- Rapid application development — Spring Boot provides a number of built-in features and starter projects that allow developers to quickly build web applications with minimal configuration.
- Simplified configuration — Spring Boot auto-configuration feature automatically configures a large portion of the application, reducing the need for manual configuration.
- Dependency management — Spring Boot manages the dependencies of the application, ensuring that all dependencies are compatible and up-to-date.
- Microservices architecture — Spring Boot is well-suited for developing microservices, as it provides the necessary tools for building and deploying small, independent services.
- Cloud-native development — Spring Boot provides integrations with cloud platforms and tools, making it easy to deploy and manage applications in the cloud.
- Security — Spring Boot provides built-in security features, such as authentication and authorization, to help protect web applications from security threats.
- Testing — Spring Boot provides tools and utilities for testing web applications, including integration testing and automated testing.
Overall, the role of a Spring Boot application is to simplify the development and deployment of Java-based web applications, allowing developers to focus on business logic and functionality rather than infrastructure and configuration.
How a Spring Boot application internally works:
- Application Startup
When you start a Spring Boot application, it first reads the configuration from the properties file or environment variables. It then creates the Spring application context and loads all the necessary beans and components. - Autoconfiguration
Spring Boot provides a lot of default configurations out-of-the-box, and it automatically configures them based on the application’s class path and other settings. This reduces the amount of boilerplate code you need to write and speeds up the application development process. - Dependency Injection
Spring Boot uses Dependency Injection (DI) to inject dependencies into various components. It supports several types of DI, including Constructor Injection, Setter Injection, and Field Injection. This helps decouple the application’s components and makes them easier to test. - Embedded Web Server
Spring Boot provides an embedded web server that allows you to run web applications without deploying them to an external server. It supports several web servers, including Tomcat, Jetty, and Undertow. This eliminates the need for manual web server configuration and simplifies the deployment process. - Spring MVC
Spring Boot uses the Spring MVC framework to handle HTTP requests and responses. It provides several annotations and classes to simplify the development of RESTful web services. This allows developers to focus on writing business logic rather than dealing with low-level details of HTTP handling. - Application Properties
Spring Boot allows you to configure various settings of the application using properties files. It supports several formats, including YAML, JSON, and Properties. This allows you to easily change the application’s configuration without modifying the code. - Profiles
Spring Boot allows you to define different profiles for different environments, such as development, testing, and production. You can configure different settings for each profile, such as database connection settings and logging levels. This makes it easy to deploy the application in different environments without making changes to the code. - Actuator
Spring Boot provides an Actuator module that provides various endpoints to monitor and manage the application. It includes endpoints for health checks, metrics, and tracing. This allows you to monitor the health of the application and troubleshoot issues easily.
Overall, Spring Boot provides a lot of conveniences and abstractions that simplify the development of web applications and microservices, making it a popular choice among developers.
Important annotations used in spring boot :
Spring Boot is a powerful and popular framework for building web applications in Java. One of the key features of Spring Boot is the use of annotations to simplify the configuration and development of web applications. In this article, we will discuss some of the most important annotations used in Spring Boot.
- @SpringBootApplication
The @SpringBootApplication annotation is a meta-annotation that combines several other annotations including @Configuration, @EnableAutoConfiguration, and @ComponentScan. It is used to indicate that a class is the main Spring Boot application class. This annotation enables automatic configuration and component scanning. - @RestController
The @RestController annotation is used to indicate that a class is a REST controller. This annotation is a combination of the @Controller and @ResponseBody annotations. It simplifies the process of building RESTful web services by automatically converting responses to JSON or XML. - @RequestMapping
The @RequestMapping annotation is used to map HTTP requests to controller methods. It is used to specify the URL path and HTTP method that a controller method should handle. This annotation can be applied at the class level to define a base URL for all methods within the controller. - @GetMapping , @PostMapping , @PutMapping , @DeleteMapping
These annotations are shortcuts for the @RequestMapping annotation with specific HTTP methods. They are used to map HTTP GET, POST, PUT, and DELETE requests to controller methods. They simplify the process of defining the HTTP method for a controller method. - @PathVariable
The @PathVariable annotation is used to extract a variable from the URL path and use it as a method parameter. It is used in conjunction with the @RequestMapping annotation. This annotation allows developers to extract dynamic data from the URL and use it in their application logic. - @RequestBody
The @RequestBody annotation is used to map the HTTP request body to a method parameter. It is used in conjunction with the @RequestMapping annotation. This annotation allows developers to extract data from the request body and use it in their application logic. - @Autowired
The @Autowired annotation is used to inject dependencies into a class. It is used to indicate that a class needs a dependency injected and Spring Boot will automatically inject the appropriate dependency. This annotation simplifies the process of managing dependencies in a Spring Boot application. - @Bean
The @Bean annotation is used to indicate that a method produces a bean to be managed by Spring Boot. It is used in conjunction with the @Configuration annotation. This annotation is used to define beans and make them available for dependency injection. - @Value
The @Value annotation is used to inject values into a class from the Spring Boot application properties file. It is used to specify the value of a property in a Spring Boot application. This annotation simplifies the process of managing configuration properties in a Spring Boot application. - @ConditionalOnProperty
The @ConditionalOnProperty annotation is used to conditionally enable or disable a component based on a property value. It is used to specify a condition that must be met in order for a component to be enabled. This annotation simplifies the process of managing application configuration and enables conditional behavior in a Spring Boot application. - @ControllerAdvice
The @ControllerAdvice annotation is used to define a class that can handle exceptions thrown by the application. It is used to provide centralized exception handling for a Spring Boot application. - @Exception Handler
The @ExceptionHandler annotation is used to define a method that can handle a specific exception thrown by the application. It is used in conjunction with the @ControllerAdvice annotation. This annotation simplifies the process of handling exceptions in a Spring Boot application. - @Configuration
The @Configuration annotation is used to define a class as a configuration class. It is used to define beans and make them available for dependency injection. This annotation is typically used in conjunction with the @Bean annotation to define beans. - @EnableAutoConfiguration
The @EnableAutoConfiguration annotation is used to enable Spring Boot’s auto-configuration mechanism. This annotation tells Spring Boot to automatically configure the application based on the class path and other settings. - @ComponentScan
The @ComponentScan annotation is used to specify the packages to be scanned for Spring components. It tells Spring Boot which packages to search for components and enables automatic component scanning. - @Transactional
The @Transactional annotation is used to indicate that a method should be executed within a transaction. It is used to simplify the process of managing database transactions in a Spring Boot application. - @EnableCaching
The @EnableCaching annotation is used to enable Spring Boot’s caching support. This annotation tells Spring Boot to enable caching for the application and provides caching-related configuration options. - @Cacheable
The @Cacheable annotation is used to indicate that the result of a method should be cached. It is used in conjunction with the @EnableCaching annotation. This annotation simplifies the process of caching data in a Spring Boot application. - @Scheduled
The @Scheduled annotation is used to schedule a method to be executed at a specified time interval. It is used to simplify the process of scheduling tasks in a Spring Boot application. - @Async
The @Async annotation is used to indicate that a method should be executed asynchronously. It is used to simplify the process of executing long-running tasks in a Spring Boot application without blocking the main thread.
In conclusion, Spring Boot’s annotations provide a simple and efficient way to configure and develop web applications. These annotations can be used to simplify the process of managing dependencies, handling exceptions, scheduling tasks, and more. By using these annotations, developers can create high-quality Spring Boot applications quickly and easily.
Some key differences between annotations of Spring Boot:
Just take a look at @Controller, @Service, and @Repository annotation definitions:
@Component
public @interface Service {
….
}
@Component
public @interface Repository {
….
}
@Component
public @interface Controller {
…
}
It’s not wrong to say that @Controller, @Service, and @Repository are special types of @Component annotation. <context:component-scan> picks them up and registers their following classes as beans, just as if they were annotated with @Component.
@Component : If we annotate a class with @Component, it tells hibernate that it is a Bean.
@Service : This tells hibernate it is a Service class where you will have @Transactional etc. Service layer annotations so hibernate treats it as a Service component.
@Repository : If we annotate a class @Repository, it tells hibernate it is a DAO class and treat it as DAO class.
@Controller: This is used to specify the controller.
