How can you specify a default value for a request parameter in a Spring Boot controller method?
- Creating a custom annotation.
- Default values for request parameters are not supported in Spring Boot.
- Setting the default value in the application.properties file.
- Using the @RequestParam annotation with the defaultValue attribute.
You can specify a default value for a request parameter in a Spring Boot controller method using the @RequestParam annotation with the defaultValue attribute. This attribute allows you to provide a default value that will be used if the parameter is not present in the request. Setting the default value in the application.properties file is not the correct approach, and creating a custom annotation is not a standard way to specify default values for request parameters.
In Spring Security, which class is primarily responsible for holding the authenticated user’s details?
- UserDetails
- UserPrincipal
- AuthenticationDetails
- SecurityContext
In Spring Security, the class primarily responsible for holding the authenticated user's details is UserDetails. It represents user information, including username, password, authorities, and account status. SecurityContext is used to hold the security context, and the other options do not typically hold user details.
In Spring Boot, _____ is used to enable caching capability in the application.
- @CacheConfig
- @Cacheable
- @EnableCaching
- @Caching
In Spring Boot, the @EnableCaching annotation is used to enable caching capability in the application. It allows you to use caching annotations like @Cacheable and @CacheEvict to control caching behavior. The other options are related to caching but not used for enabling caching at the application level.
In what scenarios would you choose to implement a custom validator instead of using the standard Bean Validation annotations?
- When you need to perform complex validation logic that can't be expressed using standard annotations.
- When you need to validate simple data types like integers and strings.
- When you want to achieve better performance in your application.
- When you want to minimize the use of custom code in your application.
Custom validators are preferred when complex validation logic is required, which can't be achieved with standard Bean Validation annotations. While standard annotations are suitable for many cases, custom validators are necessary for scenarios where specific and intricate validation rules are needed. Custom validators may increase code complexity but allow for highly tailored validation logic.
How can you use Mockito to verify that a method was called a specific number of times?
- verifyMethod(atLeast(callCount))
- verifyMethod(atMost(callCount))
- verifyMethod(callCount)
- verifyMethod(times(callCount))
In Mockito, you can use verify along with times(callCount) to verify that a method was called a specific number of times. This is useful for testing the behavior of methods.
In a Spring Boot application, how can you validate a field based on multiple conditions or constraints?
- Using only the @NotNull annotation
- Combining multiple annotations like @Min, @Max, and @Pattern
- Creating a custom validator class for each condition
- Using JavaScript to validate the field on the client-side
To validate a field based on multiple conditions or constraints in a Spring Boot application, you can combine multiple annotations like @Min, @Max, and @Pattern. These annotations allow you to define various rules for a single field. Creating a custom validator class for each condition (Option 3) would be cumbersome and is not the recommended approach.
Which grant type would be most suitable for a mobile application that needs to access services on behalf of the user?
- Authorization Code Grant
- Client Credentials Grant
- Implicit Grant
- Resource Owner Password Credentials Grant
For a mobile application that needs to access services on behalf of the user, the Authorization Code Grant is most suitable. This grant type involves a redirection-based flow where the user authenticates themselves on the authorization server, and the mobile app receives an authorization code, which can be securely exchanged for an access token. This is a more secure approach compared to the Implicit Grant, which is suitable for browser-based apps. The other grant types are not typically used for mobile apps accessing on behalf of the user.
Which Spring Security annotation is used to apply security constraints at the method level based on SpEL expressions?
- @PreFilter
- @PostFilter
- @PreAuthorize
- @PostAuthorize
The @PreAuthorize annotation is used to apply security constraints at the method level based on SpEL (Spring Expression Language) expressions. You can define complex conditions using SpEL to control method access. The other options are used for filtering, not method-level security.
How can you manage bean lifecycle events, such as initialization and destruction, in Spring Boot?
- By using the @Bean annotation with @PostConstruct and @PreDestroy methods.
- By declaring beans in an XML configuration file.
- By using the @Service annotation with initMethod and destroyMethod attributes.
- By configuring bean lifecycles in the main application class constructor.
You can manage bean lifecycle events, such as initialization and destruction, in Spring Boot by using the @Bean annotation along with @PostConstruct and @PreDestroy methods. These methods allow you to specify custom initialization and destruction logic for your beans. The other options mentioned (XML configuration, @Service with initMethod and destroyMethod, and configuring lifecycles in the main application class constructor) are not the recommended or common approaches for managing bean lifecycles in Spring Boot.
Imagine you are developing a Spring Boot application where you need to validate incoming request payloads against a complex business rule. How would you approach implementing such a validation?
- Use custom validation annotations.
- Implement validation logic in a filter or interceptor.
- Embed validation logic in the data access layer.
- Use a third-party validation library.
When dealing with complex validation rules in a Spring Boot application, one effective approach is to use custom validation annotations. This allows you to define and apply custom validation logic directly to your model classes, keeping your code clean and maintainable. While the other options may work for simpler scenarios, they are less suitable for complex business rule validation.