1. What is Spring Boot?
Answer: Spring Boot is an open-source Java-based framework used to create stand-alone, production-grade Spring-based applications easily. It simplifies the configuration and deployment of Spring applications by providing defaults for many settings and allowing developers to focus more on writing business logic.
2. What are the key features of Spring Boot?
Answer: Key features of Spring Boot include:
- Auto-configuration
- Stand-alone applications
- Opinionated defaults
- Embedded servers
- Production-ready metrics, health checks, and externalized configuration
3. Explain the difference between Spring and Spring Boot.
Answer: Spring is a comprehensive framework for building Java applications, whereas Spring Boot is a project within the Spring ecosystem that simplifies the setup and development of Spring applications. Spring Boot provides defaults and auto-configuration, reducing the need for manual configuration in Spring applications.
4. What is the purpose of the @SpringBootApplication annotation?
Answer: The @SpringBootApplication annotation is used to mark the main class of a Spring Boot application. It combines three commonly used Spring annotations: @Configuration, @EnableAutoConfiguration, and @ComponentScan. It helps in defining the primary configuration class for the application and enables various Spring Boot features.
5. Explain Spring Boot Auto-configuration.
Answer: Spring Boot Auto-configuration is a feature that automatically configures your Spring application based on the dependencies on the classpath. It eliminates the need for explicit configuration in most cases, allowing developers to get started quickly. Spring Boot detects the libraries in your classpath and sets up sensible defaults, which can be further customized if needed.
6. What is Spring Boot Starter?
Answer: A Spring Boot Starter is a pre-configured set of dependencies that help simplify the development of specific types of applications. They include a group of related libraries and provide a cohesive set of features. For example, spring-boot-starter-web includes dependencies for building web applications.
7. How do you enable cross-origin resource sharing (CORS) in a Spring Boot application?
Answer: You can enable CORS in a Spring Boot application by adding @CrossOrigin annotations to your controller methods or by configuring CORS globally using the CorsRegistry within a @Configuration class. Additionally, you can use properties in application.properties or application.yml to configure CORS globally.
8. What is Spring Boot Actuator, and why is it useful?
Answer: Spring Boot Actuator is a subproject of Spring Boot that provides production-ready features like health checks, metrics, and monitoring for your application. It is useful for monitoring and managing Spring Boot applications in production environments, as it exposes various endpoints that provide insight into the application’s health and performance.
9. Explain the difference between Spring Boot and Spring Cloud.
Answer: Spring Boot is used to create stand-alone, production-ready Spring applications, while Spring Cloud is a set of tools and libraries that build upon the Spring Boot foundation to help develop and deploy distributed systems and microservices. Spring Cloud provides solutions for service discovery, configuration management, load balancing, and more, often used in microservices architectures.
10. How can you deploy a Spring Boot application to a production environment?
Answer: You can deploy a Spring Boot application to a production environment by packaging it as a JAR or WAR file and deploying it to a web server or container. Alternatively, you can use cloud-based platforms like AWS, Azure, or Heroku to host your Spring Boot application. Continuous integration and continuous deployment (CI/CD) pipelines are often used for automated deployment.
11. What is Spring Boot, and why is it used?
Answer: Spring Boot is an open-source framework designed to simplify the setup and development of Spring applications. It provides a set of conventions and defaults for application configuration and helps developers create production-ready applications quickly. It simplifies the configuration of the Spring framework, reduces the need for boilerplate code, and enhances productivity.
12. What are the key advantages of using Spring Boot?
Answer: Some key advantages of Spring Boot are:
- Simplified configuration: Spring Boot provides sensible defaults and auto-configuration to reduce the need for manual setup.
- Embedded servers: It supports embedded containers like Tomcat, Jetty, and Undertow, making it easy to create standalone applications.
- Microservices support: Spring Boot is well-suited for building microservices, and it integrates seamlessly with Spring Cloud for service discovery and configuration.
- Production-ready features: It offers production-ready features like health checks, metrics, and externalized configuration.
13. Explain the concept of Spring Boot auto-configuration.
Answer: Spring Boot’s auto-configuration is a mechanism that automatically configures beans and application settings based on the libraries present on the classpath. It simplifies the setup of Spring applications by examining the classpath and configuring components such as data sources, messaging systems, and template engines. Developers can override these auto-configurations if needed.
14. What is the difference between Spring and Spring Boot?
Answer: Spring is a comprehensive framework for building Java applications, providing various modules like Spring MVC, Spring Data, Spring Security, etc., that need explicit configuration. Spring Boot, on the other hand, is built on top of the Spring framework and offers opinionated defaults and auto-configuration, significantly reducing the need for manual configuration.
15. How do you create a RESTful API in Spring Boot?
Answer: To create a RESTful API in Spring Boot, you typically follow these steps:
- Create a Spring Boot project.
- Define a controller class with methods annotated with
@RestControlleror@RequestMapping. - Define endpoints with appropriate HTTP methods (GET, POST, PUT, DELETE).
- Use annotations like
@GetMappingor@PostMappingto map methods to specific URLs. - Implement business logic in these methods.
16. What is the role of the@SpringBootApplication annotation?
Answer: The @SpringBootApplication annotation is used to mark the main class of a Spring Boot application. It combines three annotations: @Configuration, @ComponentScan, and @EnableAutoConfiguration. It indicates that this class is the starting point of the Spring Boot application, enabling auto-configuration and component scanning.
17. How do you externalize configuration in Spring Boot?
Answer: Spring Boot allows you to externalize configuration by using properties files (application.properties or application.yml) or environment variables. You can specify configuration values in these files, and Spring Boot will load them automatically. Additionally, you can use profiles to have different configurations for various environments.
18. Explain the difference between Spring Boot Starter and Spring Boot Actuator.
Answer:
Spring Boot Starter: A Starter is a pre-defined set of dependencies that helps you get started with a particular type of application, such as web, data, or messaging. It simplifies dependency management and ensures you have the right dependencies for your project.
Spring Boot Actuator: Spring Boot Actuator is a set of production-ready features that provide monitoring and management of your application. It includes endpoints for health checks, metrics, application info, and more, which can be useful for monitoring and managing your application in production.
19. How can you secure a Spring Boot application?
Answer: You can secure a Spring Boot application using Spring Security. By adding the Spring Security dependencies and configuring security settings in your application, you can control access to different parts of your application, implement authentication, and set up authorization rules.
20. Explain the differences between Spring Boot and Spring Cloud.
Answer:
Spring Boot: Spring Boot is a framework for simplifying the setup and development of Spring applications. It focuses on creating standalone, production-ready applications. It provides features like auto-configuration, embedded servers, and simplified configuration.
Spring Cloud: Spring Cloud is a set of tools and frameworks for building microservices-based applications. It complements Spring Boot by providing features like service discovery, configuration management, load balancing, and distributed tracing, making it easier to build and manage microservices.
Answer: Bootstrapping in Spring Boot refers to the process of initializing and configuring the Spring application context and launching the application.
22. Can you override or customize default Spring Boot properties?
Answer: Yes, you can override default properties by specifying them in your application’s property files or environment variables.
23. Explain the role of the application.properties or application.yml file in Spring Boot bootstrapping?
Answer: These files are used to configure application properties, and they allow you to customize the behavior of your Spring Boot application.
24. Explain the role of the application.properties or application.yml file in Spring Boot bootstrapping?
Answer: The SpringApplication.run method is used to launch a Spring Boot application, and it bootstraps the Spring context, initializes auto-configuration, and starts the embedded container.
25. How can you specify the active profile when launching a Spring Boot application?
Answer: You can specify the active profile using the spring.profiles.active property in the application.properties or application.yml file, or as a command-line argument when running the application.
26. Can you disable specific auto-configurations in Spring Boot, and how?
Answer: Yes, you can disable specific auto-configurations by using the spring.autoconfigure.exclude property in the application.properties or application.yml file.
27. Explain the purpose of the SpringBootServletInitializer class in a Spring Boot application.?
Answer: SpringBootServletInitializer is an abstract class you extend to configure the application for deployment to a servlet container. It allows you to override the configure method to specify the main application class.
28. What changes are required in the pom.xml file to build a Spring Boot application as a WAR?
Answer: You need to change the packaging type to war in the pom.xml and include the spring-boot-starter-tomcat as a provided dependency to prevent conflicts with the embedded Tomcat.
29. How do you package a Spring Boot application as a WAR file for deployment to Tomcat?
Answer: To create a WAR file, you need to configure your project as a web application, extend SpringBootServletInitializer, and override the configure method to specify the Spring Boot application class.
@SpringBootApplication
public class MyApplication extends
SpringBootServletInitializer {
@Override
protected SpringApplicationBuilder configure
(SpringApplicationBuilder builder) {
return builder.sources(MyApplication.class);
}
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
}
}
Answer: SpringBootServletInitializer is an abstract class you extend to configure the application for deployment to a servlet container. It allows you to override the configure method to specify the main application class.
31. What changes are required in the pom.xml file to build a Spring Boot application as a WAR?
Answer: You need to change the packaging type to war in the pom.xml and include the spring-boot-starter-tomcat as a provided dependency to prevent conflicts with the embedded Tomcat.
<packaging>war</packaging>
Answer: You can deploy the WAR file by copying it to Tomcat’s webapps directory or by using the Tomcat Manager web application.
33. Explain how to configure an external Tomcat container to run a Spring Boot application.
Answer: The external Tomcat container needs to have the necessary context configuration for the application. You can create a context.xml file in Tomcat’s conf/Catalina/localhost directory or configure it in the server.xml file. For example, to deploy an application named “myapp,” you might create a myapp.xml context file with the following content:
<Context docBase="path/to/myapp.war" />
Answer Common issues include class conflicts and dependencies with the embedded container. These can be resolved by excluding embedded containers, ensuring that dependencies are marked as provided, and verifying the correct configuration in the external Tomcat.
35.Can a Spring Boot application be deployed on Tomcat without converting it to a WAR file?
Answer Yes, you can use the embedded Tomcat container to run a Spring Boot application without converting it to a WAR. In this case, the application is packaged as a JAR file, and Tomcat is embedded within the application.
36. What is Apache Maven, and how does it relate to Spring Boot?
Answer Apache Maven is a widely used build automation tool. Spring Boot projects can be managed and built using Maven, simplifying the management of project dependencies.
37. What is the purpose of a pom.xml file in a Maven project?
Answer The pom.xml file (Project Object Model) defines the project’s metadata, dependencies, plugins, goals, and other configuration settings for building the project. How do you create a new Spring Boot project with Maven?
38. WHow do you create a new Spring Boot project with Maven?
Answer You can create a new Spring Boot project with Maven by using the Spring Initializr or by manually adding the Spring Boot dependencies to a Maven project.
39. What are Maven profiles, and why are they useful in Spring Boot projects?
Answer Maven profiles allow you to customize build configurations for different environments or use cases. They can be used to manage properties, dependencies, and other settings for various profiles.
40. Explain the role of the mvn command in a Spring Boot project.
Answer The mvn command is used to execute various Maven goals, such as building the project, running tests, packaging the application, and more.
Answer: Gradle is a modern build automation tool that provides flexibility and extensibility. Spring Boot projects can be managed and built using Gradle.
42. What is the purpose of a build.gradle file in a Gradle project?
Answer: The build.gradle file defines the project’s dependencies, tasks, plugins, and other build-related configurations for building the project.
43. What are Gradle build scripts, and how do they differ from Maven’s pom.xml files?
Answer: Gradle build scripts are written in a Groovy-based DSL (Domain Specific Language) or Kotlin. Unlike Maven’s XML-based configuration, Gradle build scripts offer a more concise and readable syntax.
44. How do you create a new Spring Boot project with Gradle?
Answer: You can create a new Spring Boot project with Gradle by using the Spring Initializr or by manually adding the Spring Boot dependencies to a Gradle project.
45. How does Maven handle dependency management in Spring Boot projects?
Answer:Maven uses a centralized repository for managing project dependencies and versions, making it easy to declare and resolve dependencies.
46. What is the purpose of the
Answer: The
47. Explain how Gradle manages dependencies in Spring Boot projects.
Answer: Gradle uses a Groovy or Kotlin DSL to specify dependencies in the build.gradle file. Dependencies can be declared using the implementation, compileOnly, or testImplementation configurations.
48. What are transitive dependencies, and how do build systems handle them?
Answer: Transitive dependencies are dependencies of dependencies. Both Maven and Gradle automatically resolve and manage transitive dependencies, ensuring that they are included in the build.
49. What are build plugins, and how are they used in Maven and Gradle?
Answer: Build plugins are used to extend the functionality of build systems. In Maven, plugins are defined in the pom.xml file, while in Gradle, they are applied in the build.gradle file.
50. What are some common build goals in Maven, and how are they executed?
Answer: Common Maven goals include clean, compile, test, package, and install. They are executed using the mvn command followed by the goal name.
51. What is the recommended package structure for a Spring Boot project?
Answer: A common package structure includes com.example.myapp (or a similar domain-specific package) as the root package. Under it, you might have subpackages for controllers, services, repositories, models, and configuration.
52. What is the primary purpose of separating your code into different packages in a Spring Boot application?
Answer: Separating code into packages helps organize and structure the application logically, making it more maintainable and enhancing code readability.
53. Explain the role of the @SpringBootApplication annotation in defining the package structure of a Spring Boot project.
Answer: The @SpringBootApplication annotation is often placed in the main application class. Spring Boot automatically scans and discovers components (controllers, services, repositories, etc.) in and below the package where this annotation is located.
54. What is the role of controllers in a Spring Boot application?
Answer: Controllers handle HTTP requests, define the application’s RESTful endpoints, and are responsible for mapping requests to appropriate methods.
55. What is a RESTful API, and how do you structure RESTful endpoints in a Spring Boot application?
Answer: A RESTful API follows a resource-based approach, where each resource has a unique URI. In Spring Boot, you can structure your endpoints by creating controller classes with methods annotated with @GetMapping, @PostMapping, etc.
56. How do you structure repository interfaces and classes in a Spring Boot project?
Answer: Repository interfaces should extend JpaRepository or a similar interface, and repository classes should implement these interfaces. They are commonly placed in a package like com.example.myapp.repository.
57. Explain the difference between model classes and entity classes in a Spring Boot application.
Answer: Model classes often represent the application’s data structures and are used for data transfer. Entity classes, on the other hand, are used for persistent storage, usually representing database tables.
58. What naming conventions are commonly used for entity classes in Spring Boot?
Answer: Entity classes are often named after the database table they map to, typically using PascalCase (e.g., Employee for an “employee” table).
59. What is a Spring Boot Runner?
Answer: A Spring Boot Runner is an interface provided by Spring Boot that allows you to run custom code when the Spring application context is fully initialized.
60. What is the purpose of using Spring Boot Runners in a Spring Boot application?
Answer: Spring Boot Runners are used to perform custom initialization or post-processing tasks after the application context is ready. They are often used for tasks like data seeding, setting up configurations, or scheduling background jobs.
Answer: Both interfaces serve a similar purpose, but CommandLineRunner provides access to command-line arguments as an array of strings, while ApplicationRunner uses an ApplicationArguments object, providing additional functionality for parsing command-line arguments.
62. How can you register a custom Runner in a Spring Boot application?
Answer: You can register a custom Runner by creating a Spring Bean of the CommandLineRunner or ApplicationRunner type. Spring Boot will automatically detect and execute these runners during application startup.
63. What is logging in the context of Spring Boot?
Answer: Logging is the process of recording application events, warnings, errors, and other information to files or consoles for debugging, monitoring, and troubleshooting purposes.
64. Explain the different log levels commonly used in logging, such as INFO, WARN, ERROR, and DEBUG.
Answer: Log levels represent the severity of a log message. For example, INFO is for general information, WARN for potential issues, ERROR for errors, and DEBUG for detailed debugging information.
65. How are the @RestController and @Controller Annotation different?
Answer: The traditional Spring @Controller annotation specifies that an annotated class represents a controller. It’s basically a @Component specialization, and it is autodetected via the classpath scanning. The @Controller annotation is used along with the annotated handler methodologies based on @RequestMapping annotations.Developers use the @RestController annotation to develop RESTful web services, utilizing the Spring Model–View–Controller (MVC). The Spring @RestController maps the request data to specified request handler methods. Once the handler method generates the response body, the @RestController modifies it to XML or JSON response.
66. How can you read the contents of a file in a Spring Boot application?
Answer: You can read the contents of a file in Spring Boot using various methods, including standard Java I/O classes, such as FileInputStream or by using higher-level abstractions like Files.readAllLines() from the java.nio.file package.
67. What is the purpose of the Resource interface in Spring Boot, and how can it be used for file handling?
Answer: The Resource interface is used to represent resources in a Spring application. It provides a consistent way to access resources, including files, from different sources like the classpath or the file system.
68. Explain the ResourceLoader in Spring Boot and how it simplifies file handling.
Answer: The ResourceLoader is a component for loading resources, such as files, from various sources. It simplifies file handling by providing a consistent API for resource access, regardless of the resource’s origin (e.g., classpath, file system, or URL).
69. How can you handle file uploads in a Spring Boot application?
Answer: File uploads can be handled in Spring Boot by creating a controller that processes MultipartFile objects, typically received from HTML forms. The uploaded file can be saved to the file system or a database.
70. What is the role of the @RequestParam annotation in handling file uploads in Spring Boot?
Answer: The @RequestParam annotation is used to bind file uploads to controller method parameters, allowing you to access the uploaded file’s contents and metadata.
71. How do you enable file uploads in a Spring Boot application using the multipart configuration?
Answer: You can enable file uploads by configuring the multipart properties in the application.properties or application.yml file, specifying settings like maximum file size and the location for storing uploaded files.
72. What are some security considerations when handling files in a Spring Boot application?
Answer: Security concerns include validating file types and sizes, ensuring proper file sanitization, and protecting against directory traversal attacks. You should also consider controlling access to files to prevent unauthorized access.
73. How can you secure file upload functionality to prevent malicious uploads in Spring Boot?
Answer: To secure file uploads, you can use validation and filtering to ensure that uploaded files are of the expected type, do not contain malicious content, and adhere to defined size limits.
74. What are the different strategies for storing uploaded files in a Spring Boot application?
Answer: Common strategies include storing files on the file system, saving them to a database as binary data, or utilizing cloud-based storage services like Amazon S3 or Google Cloud Storage.
75. How do you decide on the most suitable file storage strategy for your Spring Boot project?
Answer: The choice of storage strategy depends on factors like scalability, availability, and security requirements. Consider the trade-offs between local file storage, database storage, and cloud-based solutions based on your project’s specific needs.
76. What are service components in a Spring Boot application?
Answer: Service components are Java classes or Spring Beans that contain the business logic of an application. They serve as an intermediate layer between controllers and repositories.
77. Why are service components important in a Spring Boot application?
Answer: Service components help maintain separation of concerns by centralizing business logic, making it more organized, testable, and reusable. They also promote reusability across multiple controllers.
78. Explain the role of the @Service annotation in Spring Boot service classes.
Answer: The @Service annotation marks a class as a Spring Bean, allowing it to be automatically detected and managed by the Spring IoC container. It is commonly used to annotate service classes.
79. What responsibilities and tasks are typically associated with service components in a Spring Boot application?
Answer: Service components handle tasks such as business logic execution, data validation, data transformation, interaction with repositories, and coordination of multiple data operations.
80. Explain how transaction management is handled in service components in Spring Boot.
Answer: Transaction management is often added to service methods using annotations like @Transactional. This ensures that operations within the method are executed within a single transaction, providing atomicity and consistency.
81. What are common testing strategies for service components in Spring Boot?
Answer: Common testing strategies include unit testing service methods using tools like JUnit and Mockito, and integration testing service components within the Spring application context.
82. What is a mock object, and how is it used in testing Spring Boot service components?
Answer: A mock object is a simulated object used in unit testing. In Spring Boot, it is commonly used to isolate the service being tested from external dependencies like repositories or external services.
83. How are dependencies injected into service components in Spring Boot, and what is the purpose of dependency injection?
Answer: Dependencies are injected into service components using Spring’s dependency injection mechanism, primarily through field injection, constructor injection, or setter injection. The purpose is to provide the necessary collaborators and resources to the service.
84. What is Swagger2, and why is it used in Spring Boot applications?
Answer: Swagger2 is a framework for documenting and testing RESTful APIs. It provides a user-friendly interface for API exploration and simplifies the generation of API documentation.
85. How do you enable Swagger2 in a Spring Boot application?
Answer: To enable Swagger2, you typically add the springfox-swagger2 and springfox-swagger-ui dependencies to your project’s build file (e.g., pom.xml for Maven) and configure a Docket bean in your application.
86. Explain the purpose of the @Api and @ApiOperation annotations in Swagger2 documentation.
Answer: The @Api annotation is used at the class level to provide additional information about the API, while the @ApiOperation annotation is used at the method level to describe individual API operations.
87. What is Hibernate, and how is it integrated with Spring Boot?
Answer: Hibernate is a popular ORM framework for Java. Spring Boot integrates with Hibernate seamlessly, allowing developers to use JPA with Hibernate as the underlying implementation for data access.
88. What are repository classes in Spring Boot, and how are they used?
Answer: Repository classes, typically annotated with @Repository, are Spring Data JPA components that provide CRUD (Create, Read, Update, Delete) operations for database entities. They allow developers to perform database operations without writing SQL queries.
89. What are entity classes, and why are they important in Spring Boot applications?
Answer: Entity classes represent database tables or documents in an object-oriented manner. They define the structure of the data to be stored in the database and are managed by JPA to enable object-relational mapping.
90. What is Google Cloud Platform (GCP), and what services does it offer?
Answer: Google Cloud Platform is a suite of cloud computing services offered by Google. It provides a wide range of services, including computing, storage, databases, machine learning, and more.
91. How can you interact with Google Cloud Storage in a Spring Boot application?
Answer: You can interact with Google Cloud Storage by using the Google Cloud Storage Client Library or the Cloud Storage JSON API. Spring Boot makes it easy to use these libraries for file storage.
92. What is Google Cloud Pub/Sub, and how can you use it in a Spring Boot application?
Answer: Google Cloud Pub/Sub is a messaging service that allows asynchronous communication between components. Spring Boot applications can use the Google Cloud Pub/Sub Client Library to publish and consume messages.
93. What options are available for deploying a Spring Boot application to Google Cloud Platform?
Answer: You can deploy Spring Boot applications to GCP using services like Google App Engine, Google Kubernetes Engine (GKE), Google Compute Engine, and Google Cloud Functions.
94. How can token revocation be handled in a Spring Boot application using OAuth2?
Answer: Token revocation can be implemented by maintaining a list of valid and revoked tokens on the authorization server. Additionally, the OAuth2 Token Introspection endpoint can be used for real-time token validation.
95. What are OAuth2 scopes, and how can they be used to restrict access to resources?
Answer: OAuth2 scopes are strings that define the level of access granted by an access token. Scopes can be used to restrict the actions a client is allowed to perform within a resource server.
96. How do you configure OAuth2 with JWT in a Spring Boot application?
Answer: ou can configure OAuth2 with JWT by adding the necessary dependencies, configuring OAuth2 client and resource server properties, and specifying JWT as the token store.
97. What is the purpose of the client ID and client secret in OAuth2, and how are they used in Spring Boot applications?
Answer: The client ID and client secret are credentials used by the client to authenticate with the authorization server. In Spring Boot, these credentials are configured in the application properties or YAML file.
98. Explain the OAuth2 authorization code flow.
Answer: The authorization code flow is commonly used for web applications. It involves the client being redirected to the authorization server for user authentication. Upon successful authentication, the authorization server sends an authorization code to the client, which is exchanged for an access token.
99. What is a JSON Web Token (JWT), and how does it relate to OAuth2 in Spring Boot?
Answer: A JWT is a compact, self-contained token for securely transmitting information. In OAuth2, JWTs are often used as access tokens to represent the user’s identity and permissions.
100. What is OAuth2, and why is it used in Spring Boot applications?
Answer: OAuth2 is an open standard for authentication and authorization. In Spring Boot, OAuth2 is used to secure applications by allowing users to authenticate and grant permissions to third-party applications.
Answer: Some key features include auto-configuration, embedded servers, production-ready metrics, and a wide range of extensions for building various types of applications.
102. Explain the concept of “Auto-configuration” in Spring Boot?
Answer: Auto-configuration is a feature that automatically configures the Spring application based on the libraries and dependencies present in the classpath.
103.What is the purpose of the application.properties or application.yml files in Spring Boot??
Answer: These files are used for external configuration, allowing you to configure application properties without modifying the source code.
104.How can you create a RESTful web service in Spring Boot??
Answer: You can create a RESTful web service by creating a controller class with methods annotated with @RequestMapping or @RestController.
105.What is the difference between @RestController and @Controller in Spring Boot?
Answer: @RestController is a specialized version of @Controller that is used in RESTful web services. It automatically serializes the return value to JSON or XML.
Answer: Some key features include auto-configuration, embedded servers, production-ready metrics, and a wide range of extensions for building various types of applications.
107. Mention some advantages of Spring Boot
Answer: Here are some major advantages of using spring-boot:
- Helps you to create a stand-alone application, which can be started using java.jar.
- It offers pinpointed‘started’ POMs to Maven configuration.
- Allows you to Embed Undertow, Tomcat, or Jetty directly.
- Helps you to configure spring whenever possible automatically.
108. How to create a Spring Boot application using Spring Initializer?
Answer: It is a web tool provided by Spring on its official website. However, you can also create Spring Boot project by entering project details.
109. Name the features of using Spring Boot?
Answer: Features of using Spring Boot are:
- Starter dependency
- Auto-configuration
- Spring initializer
110. What is the process that you need to follow to run Spring Boot application on the custom port?
Answer: In order to run a Spring Boot application, you require to put server.port properties in application.properties. For example, server.port=8050
Answer: Spring Boot Actuator is a subproject of Spring Boot that provides production-ready features to help monitor and manage your application. It offers endpoints for health checks, metrics, info, and more. You can configure it in the application.properties or application.yml file,
112.What is Spring Boot’s auto-configuration, and how does it work? Can you provide an example of creating a custom auto-configuration?
Answer: Spring Boot’s auto-configuration automatically configures beans and services based on dependencies in the classpath. You can create a custom auto-configuration by defining a @Configuration class.
113. How to create a Spring Boot application using Spring Initializer?
Answer: It is a web tool provided by Spring on its official website. However, you can also create Spring Boot project by entering project details.
114. Discuss the differences between Spring Boot’s embedded servlet containers, such as Tomcat, Jetty, and Undertow. When and why would you choose one over the other?
Answer: These containers differ in performance and features. Tomcat is well-established and versatile, Jetty is known for its simplicity, and Undertow is known for performance. Choose based on your application’s specific requirements, considering factors like concurrency, resource usage, and compatibility.
115. What is Spring Boot Data JPA, and how does it simplify data access in Spring applications? Explain the role of Spring Data repositories.
Answer: Spring Boot Data JPA simplifies data access by integrating Spring Data and JPA. Spring Data repositories allow you to create database queries and perform CRUD operations without writing boilerplate code.
117.Explain the concept of Spring Boot Actuators?
Answer: Spring Boot Actuators are a set of production-ready features that help monitor and manage your application. They provide insights into the application’s runtime behavior, such as health checks, metrics, environment properties, and more. You can easily add Actuator support to your project and customize the exposed endpoints.
118. How to create a Spring Boot application using Spring Initializer? Answer: It is a web tool provided by Spring on its official website. However, you can also create Spring Boot project by entering project details.
119.How does Spring Boot support externalized configuration?
Answer: Spring Boot allows you to externalize configuration properties in various formats (e.g., YAML, properties files, environment variables). It provides property sources in a specific order, so you can override settings at different levels (e.g., application.properties, application.yml, command-line arguments) and use profiles to manage different configuration sets.
120. Explain Spring Boot’s conditional bean registration.
Answer: Conditional bean registration in Spring Boot allows you to specify under which conditions a bean should be registered in the application context. You can use conditional annotations like @ConditionalOnClass, @ConditionalOnProperty, and @ConditionalOnBean to control the registration of beans based on class availability, property values, or the presence of other beans.
Answer: @SpringBootTest loads the complete Spring application context, while @WebMvcTest loads only the web layer of the application. Use @SpringBootTest for integration tests that require the entire application context, and @WebMvcTest for testing the web layer in isolation.
122.What is Spring Boot’s CommandLineRunner, and how is it used?
Answer: CommandLineRunner is an interface in Spring Boot that allows you to execute code after the application context has been initialized. You can use it to perform tasks like database population, data migration, or any other custom startup logic.
123. How can you customize the banner in a Spring Boot application?
Answer: You can customize the banner displayed during application startup by creating a file named banner.txt or banner.gif and placing it in the classpath (typically in the src/main/resources folder). You can also set the spring.banner.location property in application.properties or application.yml to specify a custom banner file.
124. Explain the purpose of Spring Boot’s @Conditional annotations (e.g., @ConditionalOnClass, @ConditionalOnProperty).
Answer: Spring Boot’s @Conditional annotations are used to conditionally enable or disable configuration based on certain conditions. For example, @ConditionalOnClass allows you to enable a configuration bean only if a particular class is present in the classpath, and @ConditionalOnProperty allows you to enable a bean based on the existence and values of specified properties.
125. What is Spring Boot’s externalized configuration, and how can you achieve it?
Answer: Externalized configuration allows you to store configuration properties outside your application code, making it easier to change configurations without modifying the application. You can use property files, environment variables, command-line arguments, or Spring Cloud Config Server to achieve externalized configuration in Spring Boot.
126. What is the key difference between Spring Boot and the Spring Framework?
Answer: The Spring Framework is a comprehensive framework for building Java applications, while Spring Boot is an opinionated framework built on top of the Spring Framework. Spring Boot simplifies the configuration and setup of Spring applications and provides a set of conventions and tools for building production-ready applications with minimal effort.
127. Explain Spring Boot’s “opinionated” configuration.
Answer: Spring Boot is opinionated in the sense that it provides sensible defaults and pre-configured settings. It reduces the need for extensive configuration, allowing developers to focus on application logic. However, Spring Boot also allows for customization when needed.
128. What are Spring Boot Starters, and why are they important?
Answer: Spring Boot Starters are pre-configured templates that include common dependencies and settings for various types of applications. They simplify dependency management and allow developers to quickly bootstrap projects for web applications, data access, messaging, and more.
129. Explain the concept of “Spring Boot Auto-Configuration.”
Answer: Spring Boot’s Auto-Configuration automatically configures application components based on the classpath and the dependencies used in the project. This feature helps in eliminating the need for extensive configuration files by providing sensible defaults.
130. How can you customize the application’s configuration in Spring Boot?
Answer: Spring Boot provides several ways to customize configuration, including application.properties (or application.yml) files, profiles, environment properties, and custom configuration classes. You can also override default settings by providing your own configuration.
Answer: Few important features of Spring Boot are as follows:
- Spring CLI – Spring Boot CLI allows you to Groovy for writing Spring boot application and avoids boilerplate code.
- Starter Dependency – With the help of this feature, Spring Boot aggregates common dependencies together and eventually improves productivity
- Auto-Configuration – The auto-configuration feature of Spring Boot helps in loading the default configurations according to the project you are working on. In this way, you can avoid any unnecessary WAR files.
- Spring Initializer – This is basically a web application, which can create an internal project structure for you. So, you do not have to manually set up the structure of the project, instead, you can use this feature.
- Spring Actuator – This feature provides help while running Spring Boot applications.
- Logging and Security – The logging and security feature of Spring Boot, ensures that all the applications made using Spring Boot are properly secured without any hassle.
Answer: Well, there are various approaches to create a Spring Boot application using maven, but if I have to name a few, then following are the ways to create a Spring Boot project/ application using maven:
- Spring Boot CLI
- Spring Starter Project Wizard
- Spring Initializr
- Spring Maven Project
- Application Properties – By default, Spring Boot searches for the application properties file or its YAML file in the current directory, classpath root or config directory to load the properties.
- Command-line properties – Spring Boot provides command-line arguments and converts these arguments to properties. Then it adds them to the set of environment properties.
- Profile-specific properties – These properties are loaded from the application-{profile}.properties file or its YAML file. This file resides in the same location as that of the non-specific property files and the{profile} placeholder refers to an active profile.
Answer: To create a custom endpoint in Spring Boot 2.x, you can use the @Endpoint annotation. Spring Boot also exposes endpoints using @WebEndpointor, @WebEndpointExtension over HTTP with the help of Spring MVC, Jersey, etc.
137. Explain Spring Data.
Answer: Spring Data aims to make it easy for the developers to use relational and non-relational databases, cloud-based data services, and other data access technologies. So, basically, it makes it easy for data access and still retains the underlying data.
138. Can you give an example for ReadOnly as true in Transaction management?< Example for ReadOnly as TRUE in transaction management could be as follows:
Answer: Consider a scenario, where you have to read data from the database. For example, let us say you have a customer database, and you want to read the customer details such as customerID, and customername. To do that, you will set read-only on the transaction as we do not want to check for the changes in the entities.
139.. Can you explain how to deploy to a different server with Spring Boot?
Answer: To deploy a different server with Spring Boot, follow the below steps:
- Generate a WAR from the project
- Then, deploy the WAR file onto your favorite server
Answer: Yes, we can create a non-web application by removing the web dependencies from the classpath along with changing the way Spring Boot creates the application context.
