The _____ annotation in Spring Boot is used to evict specific cache entries to avoid serving stale or outdated data.
- @CacheInvalidate
- @CacheEvict
- @CacheRemove
- @EvictCache
In Spring Boot, the @CacheEvict annotation is used to evict specific cache entries, ensuring that the application does not serve stale or outdated data from the cache. It allows you to specify which cache(s) to evict when a particular method is invoked. The other options are not standard annotations for cache eviction in Spring Boot.
How can you configure different token lifetimes for different OAuth2 clients in a Spring Boot application?
- Configure token lifetimes in the application.properties file, specifying the client ID and associated expiration time.
- Token lifetimes are fixed and cannot be configured differently for different OAuth2 clients in Spring Boot.
- Use a custom TokenEnhancer to modify the token's expiration time based on the client requesting it.
- Use different OAuth2 authorization servers for each client, each with its own token configuration.
To configure different token lifetimes for different OAuth2 clients in a Spring Boot application, you can use a custom TokenEnhancer. This TokenEnhancer can modify the token's expiration time based on the client making the request. By creating a custom TokenEnhancer bean and specifying it in your OAuth2 configuration, you can dynamically adjust token lifetimes based on your specific requirements. This approach provides fine-grained control over token expiration for different clients.
You are assigned to implement Two-Factor Authentication in a Spring Security application. How would you approach this task, considering Spring Security configurations and components?
- Configure Spring Boot to use an external OTP service for two-factor authentication.
- Implement custom authentication filters to handle two-factor authentication.
- Use OAuth2 for authentication instead of two-factor authentication.
- Utilize Spring Security's built-in two-factor authentication support.
To implement Two-Factor Authentication in Spring Security, you would typically need to implement custom authentication filters to handle this process. Spring Security does provide support for two-factor authentication, but it often requires customizations based on specific requirements. OAuth2 is a different authentication mechanism and is not related to Two-Factor Authentication. Configuring Spring Boot to use an external OTP service is a specific approach, not a general method for Two-Factor Authentication.
In a Spring Boot application, you are required to develop a feature where the response body should be customized based on the client's preference. How would you implement this feature using Spring Boot annotations?
- Use the @ResponseBody annotation on controller methods and generate custom responses based on client preference in each method.
- Implement content negotiation with @RequestMapping annotations to handle client preferences automatically.
- Use the @RequestParam annotation to pass the client's preference as a parameter to controller methods and customize the response accordingly.
- Define a custom response handler class and annotate it with @RestControllerAdvice to handle client preferences for all controllers.
To implement a feature in a Spring Boot application where the response body is customized based on client preference, you should use content negotiation with @RequestMapping annotations. This allows Spring Boot to handle client preferences automatically. Option 2 is the recommended approach as it promotes clean and efficient code. The other options may require more manual coding and could be less maintainable.
In Spring Boot, the _____ interface is used to represent a reactive stream that emits multiple items.
- Multi
- Publisher
- Single
- Subscriber
In Spring Boot, the Multi interface is used to represent a reactive stream that emits multiple items. The Multi type is a reactive type that can emit zero or more items, making it suitable for scenarios where you expect multiple values to be emitted over time. This is part of the reactive programming model in Spring Boot, allowing you to work with sequences of data in a reactive manner.
When testing Spring Boot applications, how can you isolate the test context for a specific part of the application, such as a web layer?
- Using @ContextConfiguration annotation
- Using @MockBean annotation
- Using @SpringBootTest annotation
- Using @WebMvcTest annotation
To isolate the test context for a specific part of a Spring Boot application, such as a web layer, you can use the @WebMvcTest annotation. It will configure a minimal Spring application context with only the components needed for testing the web layer.
When developing reactive applications in Spring Boot, which annotation is used to define a reactive controller?
- @Controller
- @ReactiveController
- @ReactiveRest
- @RestController
In Spring Boot, when developing reactive applications, the @RestController annotation is used to define a reactive controller. This annotation is similar to the traditional @Controller annotation but is enhanced to support reactive programming. A class annotated with @RestController will handle incoming requests in a non-blocking, reactive way, allowing you to build responsive and scalable applications.
In Spring Boot, using the _____ annotation in test classes allows selectively enabling parts of the application context, making tests more focused and faster.
- @DataJpaTest
- @MockBean
- @SpringBootTest
- @WebMvcTest
In Spring Boot, the @WebMvcTest annotation allows you to focus only on the web layer while testing. It loads only the necessary components for testing the controllers and does not load the complete application context, making tests more focused and faster.
Suppose you are working on a project where you need to create several beans with business logic, database interaction, and APIs. How would you use different annotations to organize and define these beans properly?
- @Component for beans, @Service for business logic, @Repository for database interaction, and @Controller for APIs.
- @Bean for all types of beans.
- @Entity for beans, @Data for business logic, @Service for database interaction, and @RestController for APIs.
- @Resource for all types of beans.
In a Spring Boot project, it's essential to use the appropriate annotations for proper organization. Use @Component for general beans, @Service for business logic, @Repository for database interaction, and @Controller for APIs. This ensures that beans are correctly categorized, leading to better code organization and maintainability. The other options either do not follow the recommended Spring Boot annotation conventions or mix them inappropriately.
How can cache be synchronized across multiple instances of a Spring Boot application in a distributed environment?
- Use a distributed cache solution like Redis or Hazelcast.
- Implement session sharing between instances using a common database.
- Manually replicate cache data across instances using REST APIs.
- Enable cache synchronization in Spring Boot properties.
To synchronize the cache across multiple instances of a Spring Boot application in a distributed environment, you can use a distributed cache solution like Redis or Hazelcast. These tools provide distributed caching capabilities that keep cache data consistent across instances. The other options do not provide a robust and efficient solution for cache synchronization in a distributed environment.