Spring Boot

What is Spring Boot?

• Spring Boot is a framework that provides a simpler and faster way to build and deploy Spring-based applications.

• It is built on top of the Spring framework and provides features such as auto-configuration, embedded servers, and a command-line interface.

Key Features

• Auto-configuration: Spring Boot provides auto-configuration for common Spring frameworks and libraries, such as Spring MVC, JPA, and Security.

• Embedded servers: Spring Boot comes with embedded servers such as Tomcat, Jetty, and Undertow, making it easy to deploy applications as standalone executables.

• Actuator: Spring Boot Actuator provides production-ready features such as monitoring and metrics.

• Spring CLI: Spring Boot CLI provides a command-line interface for developing and testing Spring Boot applications.

Creating a Spring Boot Application

• There are several ways to create a Spring Boot application:

  • Spring Initializr: Use the Spring Initializr web application to generate a project with the required dependencies.

  • Spring Boot CLI: Use the Spring Boot CLI to create a new project using the spring init command.

  • Spring Tool Suite (STS): Use STS, an Eclipse-based IDE for Spring, to create a new Spring Boot project.

Spring Boot Annotations

• Spring Boot provides several annotations that simplify the development of Spring applications.

• Some of the key annotations include:

  • @SpringBootApplication: This annotation is used to enable Spring Boot auto-configuration and component scanning.

  • @RestController: This annotation is used to create a RESTful web service.

  • @RequestMapping: This annotation is used to map HTTP requests to methods in the controller.

  • @Autowired: This annotation is used to inject dependencies into a class.

  • @Configuration: This annotation is used to declare a class as a Spring configuration class.

  • @EnableAutoConfiguration: This annotation is used to enable Spring Boot auto-configuration.

Configuration Properties

• Spring Boot allows configuration properties to be externalized into a separate properties file or YAML file.

• Configuration properties can also be set as environment variables or command-line arguments.

• Example:

  @ConfigurationProperties(prefix = "app")
  public class AppConfig {
      private String name;
      private int port;
      // getters and setters
  }

Spring Boot Profiles

• Profiles are used to provide different configurations for different environments.

• Spring Boot allows profiles to be specified using the spring.profiles.active property.

• Example:

  @Component
  @Profile("dev")
  public class DevService implements MyService {
      // implementation for dev profile
  }
  
  @Component
  @Profile("prod")
  public class ProdService implements MyService {
      // implementation for prod profile
  }

Spring Boot Testing

• Spring Boot provides several testing annotations that simplify the testing of Spring applications.

• Some of the key annotations include:

  • @SpringBootTest: This annotation is used to start the Spring application context for integration tests.

  • @MockBean: This annotation is used to mock a Spring bean for testing purposes.

  • @AutoConfigureMockMvc: This annotation is used to configure a MockMvc instance for testing Spring MVC controllers.

• Example:

  @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
  public class MyControllerTest {
      @Autowired
      private TestRestTemplate restTemplate;
      @MockBean
      private MyService myService;
      // tests
  }

Spring Boot Actuator

• Spring Boot Actuator provides several production-ready features for monitoring and managing a Spring Boot application.

  • Some of the key features include:

    • Health checks: Actuator provides health checks to monitor the status of the application.

    • Metrics: Actuator provides metrics for monitoring the performance of the application.

    • Auditing: Actuator provides auditing for monitoring changes made to the application.

    • Tracing: Actuator provides tracing for monitoring the flow of requests through the application.

  • Example endpoints:

    • /actuator/health: Provides health information about the application.

    • /actuator/info: Provides custom information about the application.

    • /actuator/metrics: Provides metrics about the application.

    • /actuator/httptrace: Provides tracing information about HTTP requests.

  Spring Boot Data

  • Spring Boot provides several libraries for working with databases and data stores.

  • Some of the key libraries include:

    • Spring Data JPA: Provides support for working with relational databases using the Java Persistence API (JPA).

    • Spring Data MongoDB: Provides support for working with MongoDB.

    • Spring Data Redis: Provides support for working with Redis.

  • Example usage:

    @Repository
    public interface MyRepository extends JpaRepository<MyEntity, Long> {
        // custom queries
    }
    
    @Service
    public class MyService {
        @Autowired
        private MyRepository myRepository;
        // business logic
    }

  Spring Boot Security

  • Spring Boot provides several features for securing web applications.

  • Some of the key features include:

    • Authentication: Spring Security provides support for authenticating users using various mechanisms such as form-based login, HTTP Basic authentication, and OAuth 2.0.

    • Authorization: Spring Security provides support for securing access to resources based on roles and permissions.

    • CSRF protection: Spring Security provides support for protecting against Cross-Site Request Forgery (CSRF) attacks.

  • Example usage:

    @Configuration
    @EnableWebSecurity
    public class SecurityConfig extends WebSecurityConfigurerAdapter {
        @Override
        protected void configure(HttpSecurity http) throws Exception {
            http.authorizeRequests()
                .antMatchers("/admin/**").hasRole("ADMIN")
                .antMatchers("/user/**").hasRole("USER")
                .anyRequest().authenticated()
                .and()
                .formLogin()
                .and()
                .httpBasic();
        }
    }

  Conclusion

  Spring Boot is a powerful framework that provides a simpler and faster way to build and deploy Spring-based applications. It provides several features such as auto-configuration, embedded servers, and a command-line interface that make it easy to develop and test applications. Spring Boot also provides several libraries for working with databases and data stores, as well as features for securing web applications.