Common Spring Interview Questions & Answers For Freshers

Last updated on 10th Jun 2020, Blog, Interview Questions

Java Spring is a robust and versatile framework designed to simplify the development of Java applications, particularly those at the enterprise level. At its core, Spring emphasizes Inversion of Control (IoC) and Dependency Injection (DI), enabling developers to create modular, loosely coupled components. This approach enhances code organization and testability. With support for Aspect-Oriented Programming (AOP), Spring allows the separation of cross-cutting concerns, such as logging and security, from the main business logic.

1. What is Spring?

Ans:

Spring is an open-source development framework for Enterprise Java. The core features of Spring Framework can be used in developing any Java application, but there are extensions for building web applications on top of Java EE platform. Spring framework aims to make Java EE development simpler to use and promote good programming practice by enabling POJO-based programming models.

2. What are the benefits of Spring Framework?

Ans:

Lightweight: Spring is lightweight when it comes to size and transparency.

Inversion of control (IOC): Loose coupling is achieved in the Spring, with Inversion of Control technique.

Aspect-oriented (AOP): Spring supports Aspect-oriented programming and separates application business logic from system services.

Container: Spring contains and manages life cycle and configuration of application objects.

MVC Framework: Spring’s web framework is a well-designed web MVC framework, which provides a great alternative to web frameworks.

3. Explain Core Container (Application context) module.

Ans:

This is a basic Spring module, which provides a fundamental functionality of Spring framework. BeanFactory is the heart of any spring-based application. Spring framework was built on top of this module, which makes a Spring container.

4. What is BeanFactory – BeanFactory implementation?

Ans:

A BeanFactory is the implementation of a factory pattern that applies inversion of control to separate application’s configuration and dependencies from the actual application code. The most commonly used BeanFactory implementation is the XmlBeanFactory class.

5. Which are Spring framework modules?

Ans:

• Core module
• Bean module
• Context module
• Expression Language module
• JDBC module
• ORM module
• OXM module

6. What is XMLBeanFactory?

Ans:

The most useful one is org.springframework.beans.factory.xml. XmlBeanFactory, which loads its beans based on definitions contained in an XML file. This container reads configuration metadata from an XML file and uses it to create a fully configured system or application.

7. Explain AOP module.

Ans:

The AOP module is used for developing the aspects for Spring-enabled application. Much of support has been provided by AOP Alliance in order to ensure the interoperability between the Spring and other AOP frameworks. This module also introduces the metadata programming to Spring.

8. What are the benefits of IOC?

Ans:

IOC or dependency injection minimizes the amount of code in an application. It makes it simple to test applications since no singletons or JNDI lookup mechanisms are required in the unit tests.

Loose coupling is promoted with the minimal effort and least intrusive mechanism. IOC containers support the eager instantiation and lazy loading of the services.

9. What are the differences between Spring AOP and AspectJ AOP?

Ans:

	Feature	Spring AOP	AspectJ AOP
Integration	Integrated with the Spring framework	Independent of Spring, can be used anywhere
Type of AOP	Proxy-based	Weaving-based (compile-time, load-time, runtime)
Configuration	XML or annotation-based	AspectJ-specific syntax and configuration
JoinPoint Expressions	Limited expressions	Powerful and expressive pointcut expressions

10. What is a Spring IoC container?

Ans:

The Spring IoC is responsible for creating the objects, managing them (with the dependency injection (DI)), wiring them together, configuring them, as well as managing complete lifecycle.

11. Explain a web module.

Ans:

The Spring web module is built on an application context module, providing the context that is appropriate for a web-based application. This module also contains support for the several web-oriented tasks such as transparently handling multipart requests for file uploads and programmatic binding of request parameters to business objects. It also contains integration support with Jakarta Struts.

12. What distinguishes BeanFactory from ApplicationContext?

Ans:

Application contexts provide the means for resolving text messages, a generic way to load file resources; they can publish events to beans that are registered as listeners. In addition, operations on containers or beans in a container, which have to be handled in the programmatic fashion with the bean factory, can be handled declaratively in application context. The application context implements the MessageSource, an interface used to obtain the localized messages, with the actual implementation pluggable.

13. What does a Spring application look like?

Ans:

• An interface that defines functions.
• The implementation that contains the properties, its setter and getter methods, functions, etc.
• Spring AOP
• A Spring configuration XML file
• A client program that uses function

14. What is the Spring configuration file?

Ans:

The Spring configuration file is the XML file. This file contains the class information and describes how these classes are configured and introduced to each other.

15. What is Dependency Injection in Spring?

Ans:

Dependency Injection, an aspect of the Inversion of Control (IoC), is a general concept, and it can be expressed in more different ways. This concept says that do not create objects but describe how they should be created. And don’t directly connect the components and services together in code but describe which services are needed by which components in the configuration file. A container (the IOC container) is responsible for hooking it all up.

16. What are different types of IoC (dependency injection)?

Ans:

Constructor-based dependency injection: Constructor-based DI is accomplished when a container invokes the class constructor with a number of arguments, each representing the dependency on another class.

Setter-based dependency injection: Setter-based DI is accomplished by container calling setter methods on the beans after invoking a no-argument constructor or no-argument static factory method to the instantiated bean.

17. What are Spring beans?

Ans:

The Spring Beans are the Java Objects that form the backbone of a Spring application. They are instantiated, assembled, and managed by a Spring IoC container. These beans are created with configuration metadata that is supplied to the container, for example, in the form of XML definitions.

18. How do you provide configuration metadata to the Spring Container?

Ans:

There are three important methods to provide the configuration metadata to Spring Container:

• An XML-based configuration file
• Annotation-based configuration
• Java-based configuration

19. How do you define the scope of a bean?

Ans:

When defining Spring, can also declare a scope for beans. It can be defined through the scope attribute in bean definition. For example, when Spring has to produce the new bean instance each time one is needed, the bean’s scope attribute to be prototype. On other hand, when the same instance of bean must be returned by Spring every time it is needed, bean scope attribute must be set to singleton.

20. What does the Spring Bean definition contain?

Ans:

A Spring Bean definition contains all the configuration metadata that is needed for a container to know how to create a bean, its lifecycle details, and its dependencies.

21. Explain bean scopes supported by Spring.

Ans:

• In singleton scope, Spring scopes bean definition to a single instance per Spring IoC container.
• In prototype scope, single bean definition has any number of the object instances.
• In request scope, bean is defined as HTTP request. This scope is valid only in the web-aware Spring ApplicationContext.
• In session scope, a bean definition is scoped to HTTP session. This scope is also valid only in the web-aware Spring ApplicationContext.
• In the global-session scope, bean definition is scoped to the global HTTP session. This is also the case used in the web-aware Spring ApplicationContext.

22. What are inner beans in Spring?

Ans:

When a bean is only used as the property of another bean it can be declared as an inner bean. Spring’s XML-based configuration metadata provides use of elements inside the or elements of bean definition, in order to define so-called inner beans. Inner beans are always anonymous and they are always scoped as the prototypes.

23. What are the important beans lifecycle methods?

Ans:

The first one is set up which is called when the bean is loaded into the container. The second method is a teardown method which is called when a bean is unloaded from a container.

The bean tag has two important attributes (init-method and destroy-method) with which it can define its own custom initialization and destroy methods. There are also corresponding annotations(@PostConstruct and @PreDestroy).

24. What is bean wiring?

Ans:

Wiring, or bean wiring is a case when beans are combined together within the Spring container. When wiring beans, the Spring container needs to know what beans are needed and how the container should use the dependency injection to tie them together.

25. Explain the Bean lifecycle in the Spring framework.

Ans:

• The spring container finds bean’s definition from XML file and instantiates bean.
• Spring populates all of the properties as specified in a bean definition (DI).
• If bean implementsBeanNameAware interface, spring passes bean’s id to setBeanName().
• If Bean implementsBeanFactoryAware interface, spring passes bean factory to setBeanFactory().
• If bean implementsDisposableBean, it will call destroy().

26. What is bean auto wiring?

Ans:

The Spring container is able to autowire relationships between the collaborating beans. This means that it is possible to automatically let Spring resolve collaborators (other beans) for beans by inspecting the contents of BeanFactorywithout using any elements.

27. What are the limitations with auto wiring?

Ans:

Overriding: Can still specify the dependencies using and settings that will always override auto wiring.

Primitive data types: Cannot auto-wire simple properties like primitives, Strings, and Classes.

Confusing nature: Autowiring is less exact than explicit wiring, so if possible prefer using an explicit wiring.

28. What is Spring Java-Based Configuration?

Ans:

The java-based configuration option enables to write most of the Spring configuration without XML but with the help of a few Java-based annotations. An example is @Configuration annotation, which indicates that class can be used by Spring IoC container as a source of bean definitions. Another example is the@Bean annotated method that will return an object that should be registered as bean in a Spring application context.

29. How do you turn on annotation wiring?

Ans:

Annotation wiring is not turned on in a Spring container by default. In order to use the annotation-based wiring, you must enable it in the Spring configuration file by configuring an element.

30. Explain the different modes of auto wiring.

Ans:

no: This is a default setting. An explicit bean reference should be used for the wiring.

byName: When auto-wiring byName, Spring container looks at properties of the beans on which auto-wire attribute is set to byName in the XML configuration file.

byType: When autowiring by data type, Spring container looks at properties of beans on which auto-wire attribute is set to byType in the XML configuration file.

constructor: This mode is similar tothe byType, but type applies to constructor arguments. If there is not exactly one bean of the constructor argument type in the container, fatal error is raised.

31. What is Annotation-based container configuration?

Ans:

An alternative to the XML setups is provided by annotation-based configuration that relies on a bytecode metadata for wiring up components instead of angle-bracket declarations.

Instead of using the XML to describe the bean wiring, the developer moves configuration into component class itself by using annotations on relevant class, method, or field declaration.

32. What is @Required annotation?

Ans:

This annotation simply indicates that affected bean property must be populated at a configuration time, through an explicit property value in the bean definition, or through the auto wiring. The container throws the BeanInitializationException if the affected bean property has not been populated.

33. What is @Autowired annotation?

Ans:

• The @Autowired annotation provides the more fine-grained control over where and how auto wiring should be accomplished.
• It can be used to the auto-wire bean on the setter method just like @Required annotation, on constructor, on a property, or on methods with the arbitrary names and/or multiple arguments.

34. What is @Qualifier annotation?

Ans:

When there are more than one bean of the same type and only one is needed to be wired with the property, the@Qualifier annotation is used along with the @Autowired annotation to remove confusion by specifying which exact bean will be wired.

35. How can JDBC be used more efficiently in the Spring framework?

Ans:

When using Spring JDBC framework the burden of resource management and error handling is reduced. So developers only need to write statements and queries to get data to and from database. JDBC can be used more efficiently with help of a template class provided by a Spring framework, which is the JdbcTemplate

36. What is JdbcTemplate?

Ans:

JdbcTemplate class provides many convenient methods for doing things such as converting database data into the primitives or objects, executing prepared and callable statements, and providing a custom database error handling.

37. What is Spring DAO support?

Ans:

The Data Access Object (DAO) support in the Spring is aimed at making it easy to work with the data access technologies like JDBC, Hibernate, or JDO in a consistent way.

This allows us to switch between persistence technologies fairly easily and to code without worrying about the catching exceptions that are specific to each technology.

38. What are the ways to access Hibernate by using Spring?

Ans:

There are the two ways to access Hibernate with Spring:

• Inversion of Control with the Hibernate Template and Callback.
• ExtendingHibernateDAOSupport and Applying AOP Interceptor node.

39. How can I integrate Spring and Hibernate using HibernateDaoSupport?

Ans:

Use the Spring’s SessionFactory called LocalSessionFactory. The integration process is three steps:

• Configure Hibernate SessionFactory
• Extend the DAO Implementation fromHibernateDaoSupport
• Wire in Transaction Support with the AOP

40. What are types of transaction management Spring support?

Ans:

Programmatic transaction management: This means that they have managed transactions with the help of programming that gives extreme flexibility, but it is complex to maintain.

Declarative transaction management: This means separate transaction management from a business code. And only use annotations or XML-based configuration to manage transactions.

41. Which Transaction management type is more preferable?

Ans:

Most users of the Spring Framework choose declarative transaction management because it is the option with the least impact on application code, and hence it is most consistent with ideals of a non-invasive lightweight container.

Declarative transaction management is preferable over the programmatic transaction management though it is less flexible than programmatic transaction management, which allows to control transactions through the code.

42. Explain AOP.

Ans:

Aspect-oriented programming, or AOP, is the programming technique that allows the programmers to modularize crosscutting concerns or behavior that cuts across the typical divisions of responsibility, like logging and transaction management.

43. What is Joinpoint?

Ans:

• The joinpoint represents the point in an application where you can plug in an AOP aspect.
• It is an actual place in application where an action will be taken using Spring AOP framework.

44. What is Advice?

Ans:

The advice is an actual action that will be taken either before or after method execution. This is an actual piece of code that is invoked during the program execution by a Spring AOP framework.

45. What is Spring MVC framework?

Ans:

Spring comes with the full-featured MVC framework for building web applications. Although Spring can easily be integrated with other MVC frameworks, like Struts, Spring’s MVC framework uses the IoC to provide a clean separation of controller logic from business objects. It also allows to declaratively bind the request parameters to the business objects.

46. What are different types of AutoProxying?

Ans:

The different types of the AutoProxying are:

• BeanNameAutoProxyCreator
• DefaultAdvisorAutoProxyCreator
• Metadata auto proxying

47. What is Weaving?

Ans:

Weaving is a process of linking aspects with the other application types or objects to create an advised object. Weaving can be done at a compile-time, at load time, or at runtime.

48. What is WebApplicationContext?

Ans:

The WebApplicationContext is the extension of the plain ApplicationContext that has some extra features necessary for the web applications. It differs from a normal ApplicationContext in that it is capable of resolving themes, and that it knows which servlet it is associated with.

49. What is Proxy?

Ans:

• A proxy is the object that is created by applying the advice to the target object.
• When thinking of the client objects the target object and proxy object are the same.

50. What is Controller in Spring MVC framework?

Ans:

Controllers provide access to application behavior that are typically defined through the service interface. Controllers interpret user input and transform it into a model that is represented to the user by the view. Spring implements the controller in a very abstract way, which enables it to create a wide variety of controllers.

51. What is @Controller annotation?

Ans:

The @Controller annotation indicates that the particular class serves a role of a controller. Spring does not require to extend any controller base class or reference the Servlet API.

52. List the various modules within the Spring framework.

Ans:

• Web-Portlet
• Web-Struts
• Web-Servlet
• Web module
• Transaction module
• JMS (Java Messaging Service)
• OXM module

53. How do you implement DI in Spring Framework?

Ans:

You can use the Spring XML based as well as Annotation-based configuration to implement DI in spring applications. For a better understanding, please read the Spring Dependency Injection example where you can learn both ways with the JUnit test case. The post also contains the sample project zip file, that you can download and play around to learn more.

54. What are the benefits of using Spring Tool Suite?

Ans:

Install the plugins into Eclipse to get all the features of Spring Tool Suite. However, STS comes with the Eclipse with some other important kinds of stuff such as Maven support, Templates for creating various types of Spring projects, and TC server for a better performance with Spring applications.

55. Name some of the important Spring Modules.

Ans:

Spring Context: For a dependency injection.

Spring AOP: For aspect-oriented programming.

Spring DAO: For a database operations using DAO pattern.

Spring ORM: For ORM tools support Hibernate.

Spring Web Module: For creating web applications.

Spring MVC: Model-View-Controller implementation for creating web applications, web services.

56. What are the five kinds of advice that Spring can work with?

Ans:

before: Run advice before a method execution.

after: Run advice after method execution regardless of its outcome.

after-returning: Run advice after method execution only if method completes successfully.

after-throwing: Run advice after method execution only if method exits by throwing an exception.

around: Run advice before and after the advised method is invoked.

57. Does Spring Bean provide thread safety?

Ans:

The default scope of the Spring bean is singleton, so there will be only one instance per context. That means that all having a class level variable that any thread can update will lead to inconsistent data. Hence in a default mode spring beans are not thread-safe.

58. Which DI suggests Constructor-based or setter-based DI?

Ans:

In Spring’s Dependency Injection (DI), the choice between constructor-based and setter-based DI hinges on the nature of dependencies. Constructor-based DI is recommended when dependencies are mandatory for an object’s proper functioning, promoting immutability and ensuring a consistent state upon instantiation.

Conversely, setter-based DI is suitable for optional or dynamically changing dependencies, providing flexibility for adjustments during the object’s lifecycle. This approach accommodates evolving requirements but may not enforce the same level of immutability as constructor injection.

59. What is Spring JdbcTemplate class ?

Ans:

Spring Framework provides an excellent integration with the JDBC API and provides the JdbcTemplate utility class that can be used to avoid bolier-plate code from our database operations logic like Opening/Closing Connection, ResultSet, PreparedStatement etc.

60. Explain @InitBinder.

Ans:

• This annotation is decorated on the method in which a date format is declared, and throughout class, the defined date format is used.
• Whenever binding happens with the date field @InitBinder; annotation says to use the CustomDateEditor, which in return uses a date format mentioned in @InitBinder.

61. What is Spring JdbcTemplate class?

Ans:

Spring Framework provides an excellent integration with the JDBC API and provides the JdbcTemplate utility class that can be used to avoid bolier-plate code from our database operations logic like Opening/Closing Connection, ResultSet, PreparedStatement etc.

62. Explain @ModelAttribute annotation.

Ans:

The @ModelAttribute annotation refers to the property of the Model object and is used to prepare the model data. This annotation binds the method variable or the model object to the named model attribute. The annotation accepts an optional value which indicates the name of the model attribute. The @ModelAttribute annotation can be used at parameter level or method level.

63. What is the advantage of NamedParameterJdbcTemplate?

Ans:

NamedParameterJdbcTemplate is built upon the JDBCTemplate which is provided by a spring and used for lower level communication with databases. It makes possible to pass the SQL query arguments as key value pairs. As a result program code is much more readable and therefore serves as better documentation compared to indexed or the “?” placeholder approach. The latter is harder to follow, especially if number of parameters is huge.

64. What are the benefits of Spring Framework’s transaction management?

Ans:

• It provides a consistent programming model across the different transaction APIs such as JTA, JDBC, Hibernate, JPA, and JDO.
• It provides a simpler API for programmatic transaction management than a number of complex transaction APIs such as JTA.
• It supports declarative transaction management.
• It integrates very well with Spring’s various data access abstractions.

65. What is @ModelAttribute annotation?

Ans:

The @ModelAttribute annotation in the Spring MVC is used to bind method parameters or method return values to the model attributes. It plays a crucial role in Model-View-Controller (MVC) architecture, where it helps transfer data between Controller and the View.

66. What is AOP terminology?

Ans:

AOP (Aspect-Oriented Programming) terminology includes “Aspect” (module for cross-cutting concerns), “Join Point” (specific program execution point), “Advice” (action at a join point), “Pointcut” (set of join points), and “Weaving” (integrating aspects with the main program).

67. How can you inject Java Collection in Spring?

Ans:

In Spring, injecting Java collections is a straightforward process, providing flexibility and ease in managing multiple elements within an application. To inject Java collections, such as lists, sets, or maps, you can leverage the Spring IoC container’s capabilities. This can be accomplished using XML-based configuration or through annotations in Java-based configuration. For instance, to inject a list in XML configuration:

68. What is the importance of session scope?

Ans:

The session scope in the Spring is an important mechanism for managing beans in the web applications. It allows the creation and maintenance of a separate instance of a bean for each user session, ensuring that data associated with the specific user is preserved throughout interactions with the application.

69. What are the common implementations of the ApplicationContext?

Ans:

• The FileSystemXmlApplicationContext container loads definitions of beans from an XML file. The full path of the XML bean configuration file must be provided to a constructor.
• The ClassPathXmlApplicationContext container also loads definitions of beans from an XML file. Here, you need to set CLASSPATH properly because this container will look like a bean configuration XML file in the CLASSPATH.
• The WebXmlApplicationContext container loads an XML file with definitions of all beans from within the web application.

70. How is root application context in Spring MVC loaded?

Ans:

• The root application context in the Spring MVC is loaded automatically during the web application startup by ContextLoaderListener.
• It handles the overall configuration and bean management for application, while DispatcherServlet handles web-specific components and request handling.

71. Where does access to model from view come from?

Ans:

In Spring MVC, Model object acts as the container to pass data from Controller to the View for rendering. The Model is automatically made available to the View by DispatcherServlet, and the View can access the data using expression language or template-specific syntax. This allows for a separation of data handling and presentation concerns in application.

72. Why do you need BindingResults in Spring MVC?

Ans:

BindingResult is used in the Spring MVC for data binding and validation. It captures the errors during form submission, helps to prevent exceptions, and allows handling errors gracefully by displaying the error messages to users.

73. List out all concepts available in MVC Architecture.

Ans:

• The browser sends the request to DispatcherServlet.
• DispatcherServlet knows HanderMapping and can find appropriate controllers.
• Controllers execute requests and put the data in a model and return the view name to DispatcherServlet.
• DispatcherServlet uses view name and ViewResolver to map to view.

74. What are Spring Interceptors?

Ans:

Spring Interceptors are the components in Spring MVC framework that allow you to intercept and process HTTP requests and responses. They provide a way to perform pre-processing and post-processing tasks before and after an actual request is handled by the controller or after a response is generated.

75. How are i18n and localization supported in Spring MVC?

Ans:

• Internationalization (i18n) and localization (L10n) are the important features for the applications that need to support multiple languages or locales.
• In Spring MVC, these are supported using the combination of LocaleResolver, LocaleChangeInterceptor, and message source properties files.

76. How does Scope Prototype work?

Ans:

Scope prototype means that every time you call for an instance of Bean, Spring will create the new instance and return it. This differs from a default singleton scope, where a single object instance is instantiated once per Spring IoC container.

77. What is Spring WebFlux?

Ans:

• Spring WebFlux is a Spring’s reactive-stack web framework, and it’s alternative to Spring MVC.
• In order to achieve this reactive model and be more scalable, entire stack is non-blocking.

78. What is Reactive Programming?

Ans:

Reactive programming is about the non-blocking, event-driven applications that scale with the small number of threads, with back pressure being a key ingredient that aims to ensure the producers don’t overwhelm consumers.

79. What are Mono and Flux types?

Ans:

• The WebFlux framework in the Spring Framework 5 uses Reactor as its async foundation.
• This project provides the two core types: Mono to represent the single async value and Flux to represent a stream of the async values.
• They both also implement the Publisher interface defined in a Reactive Streams specification.

80. What are the disadvantages of using Reactive Streams?

Ans:

• Troubleshooting the Reactive application is a bit difficult.
• There is limited support for reactive data stores since traditional relational data stores have yet to embrace reactive paradigm.
• There’s an extra learning curve when implementing.

81. What is the difference between a singleton and a prototype scope in Spring?

Ans:

In Spring, a singleton-scoped bean is a single instance managed by the Spring IoC container. It is created when the container is initialized and remains the same throughout the application’s lifecycle.

On the other hand, a prototype-scoped bean is a new instance created each time it is requested. Prototype beans are not cached, and a new object is provided whenever the bean is injected or looked up.

82. Explain the purpose of the ‘@Qualifier’ annotation in Spring.

Ans:

• The ‘@Qualifier’ annotation is used to resolve ambiguity when there are multiple beans of the same type in the Spring context.
• It is applied along with the ‘@Autowired’ annotation on the injection point.
• By specifying the desired bean’s unique name or ID as a qualifier, you indicate which bean should be injected.

83. How does Spring support declarative transaction management?

Ans:

• Spring simplifies declarative transaction management through the ‘@Transactional’ annotation.
• By annotating a method with ‘@Transactional’, developers can define transactional behavior without explicit programmatic management.

84. Explain the role of the Spring ‘BeanPostProcessor’ interface.

Ans:

The ‘BeanPostProcessor’ interface allows developers to customize the instantiation and initialization process of Spring beans. It consists of two methods, ‘postProcessBeforeInitialization’ and ‘postProcessAfterInitialization’, which are invoked before and after a bean is initialized, respectively.

85. How does the Spring Security framework contribute to application security?

Ans:

Spring Security is a comprehensive framework for handling security concerns in Java applications. It provides authentication and authorization mechanisms to secure applications against unauthorized access.

With features such as authentication providers, access control, and protection against common vulnerabilities like cross-site scripting (XSS) and cross-site request forgery (CSRF), Spring Security enhances the overall security posture of Spring applications.

86. How does Spring support method-level caching?

Ans:

Spring provides support for method-level caching through annotations like ‘@Cacheable’, ‘@CacheEvict’, and ‘@CachePut’. Developers can annotate methods with these caching annotations to specify caching behavior. When a method is invoked, Spring checks the cache before executing the method body. If the result is found in the cache, the cached value is returned instead of executing the method.

87. Describe the Spring Boot Starter’s function.

Ans:

A Spring Boot Starter is a convenient way to package a set of dependencies and configurations for specific functionalities. It simplifies project setup by providing a pre-packaged, ready-to-use set of dependencies for common scenarios. For instance, the ‘spring-boot-starter-web’ includes everything needed for building web applications, such as embedded web server dependencies, Spring MVC, and more.

88. How does Spring support method interception?

Ans:

• Spring supports method interception through Aspect-Oriented Programming (AOP).
• AOP allows developers to define cross-cutting concerns, such as logging or security, in separate aspects.
• Spring AOP provides a proxy-based mechanism for intercepting method calls and applying aspects.

89. What is the purpose of Spring Boot Actuator?

Ans:

Spring Boot Actuator is a set of production-ready features aimed at monitoring and managing Spring Boot applications. It provides built-in endpoints that expose information about application health, metrics, and other runtime information. By including Actuator in a Spring Boot application, developers gain access to endpoints like ‘/actuator/health’, ‘/actuator/metrics’, and more.

90. What is the purpose of the Spring ‘ApplicationContext’ interface?

Ans:

The ‘ApplicationContext’ interface in Spring extends the ‘BeanFactory’ and provides additional functionalities, making it a more feature-rich container. Unlike ‘BeanFactory’, ‘ApplicationContext’ includes support for internationalization, event propagation, and a more advanced mechanism for wiring components.