In this article, we are going to delve into some of the most frequently asked Spring interview questions along with their answers. As we know spring framework is a very popular framework for developing Java applications, So while giving Java interviews interviewers ask most of the questions on the spring framework. Here, we are not going to make it complicated; rather, we are going to explain these questions with their answers in a nutshell. So that it will help you to easily prepare for the responses you should provide in your Java-related interviews.
1. What is Spring Framework?
The Spring Framework is a comprehensive and lightweight open-source framework for building enterprise-level Java applications. It provides infrastructure support and various modules to simplify development tasks, such as dependency injection, aspect-oriented programming, and transaction management.
2. What are the features of Spring Framework?
The Spring Framework offers a wide range of features, including dependency injection (DI), aspect-oriented programming (AOP), transaction management, JDBC abstraction, integration with ORM frameworks, MVC web application development, and support for various application architectures.
3. What is IOC Container?
IOC (Inversion of Control) Container is the core component of the Spring Framework responsible for managing Java objects (beans) and their dependencies. It removes the responsibility of instantiating and managing objects from the application code and instead delegates it to the container.
4. What are the types of IOC container in Spring?
Spring provides two types of IOC containers: BeanFactory and ApplicationContext. BeanFactory is a basic container that lazily initializes beans, while ApplicationContext is a more advanced container that eagerly initializes beans and provides additional features such as internationalization and event publication.
5. What is the difference between BeanFactory and ApplicationContext?
The main difference between BeanFactory and ApplicationContext is in their features and initialization behavior. ApplicationContext provides more features like internationalization, event publication, and eagerly initializes beans during startup, whereas BeanFactory offers basic container functionality and lazily initializes beans.
6. What is a Spring configuration file?
A Spring configuration file is an XML or Java-based file that contains configuration metadata for defining beans, dependencies, and other application settings. It specifies how beans are created, wired together, and managed by the Spring container.
7. What is a Spring Bean?
A Spring Bean is a Java object managed by the Spring IoC container. Beans are defined in the Spring configuration file and represent the components of an application, such as services, data access objects, or controllers.
8. What are the different scopes of Spring Bean?
Spring beans can have different scopes, including singleton, prototype, request, session, and custom scopes. The scope determines the lifecycle and visibility of a bean within the application context.
9. What is the Spring Bean’s life cycle?
The Spring Bean lifecycle consists of several phases like first, the bean is instantiated based on its configuration then, dependencies are injected and properties are set. Next, any initialization methods are invoked, allowing for custom setup logic. Once initialized, the bean is ready for use by other components in the application. Then at last the bean get destroyed, releasing any resources it holds, either through implementing the DisposableBean interface or specifying a custom destroy method. Finally, when the bean is no longer referenced, it becomes eligible for garbage collection, reclaiming its memory resources.
10. What is the use of @Autowired annotation?
The @Autowired annotation is used to automatically inject dependent class objects into a target class. Instead of manually creating instances of dependent classes and passing them to your class, you just mark a variable with '@Autowired', and Spring takes care of finding the right dependency and providing it for you.
11. What is the use of @Controller in Spring MVC?
The @Controller annotation is used to mark a class as a controller in Spring MVC. Controllers handle incoming requests, process them, and return appropriate responses. They typically interact with service layer components to perform business logic.
12. What does @RequestMapping annotation?
The @RequestMapping annotation is used to map HTTP requests to handler methods in Spring MVC controllers. It specifies the URL patterns that a controller method can handle and the HTTP methods it supports.
13. What does the ViewResolver class?
The ViewResolver class is responsible for resolving logical view names returned by controller methods to actual view implementations. It determines which view template to render based on the view name and view resolution strategy configured in the Spring application context.
14. What is Spring Security?
Spring Security is a powerful and customizable authentication and access control framework for Java applications. It provides comprehensive security features such as authentication, authorization, session management, and protection against common security threats.
15. What are some of the important Spring annotations you have used?
Some important Spring annotations include @Autowired for dependency injection, @Controller for marking MVC controllers, @RequestMapping for URL mapping, @Component for marking Spring-managed components, @Service for marking service layer components, and @Repository for marking data access objects (DAOs).
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