Spring Security Interview Questions And Answers Pdf

1. What do you mean by Dependency Injection?
Answer: In Dependency Injection, you do not have to create your objects but have to describe how they should be created. You don’t connect your components and services together in the code directly, but describe which services are needed by which components in the configuration file. The IoC container will wire them up together.(Mulesoft Training )

2. What is Dispatcher Servlet and Context Loader Listener?
Answer: DispatcherServlet is the front controller in the Spring MVC application and it loads the spring bean configuration file and initializes all the beans that are configured. If annotations are enabled, it also scans the packages and configures any bean annotated with @Component, @Controller, @Repository or @Service annotations.
ContextLoaderListener is the listener to start up and shut down Spring’s root WebApplicationContext. Its important functions are to tie up the lifecycle of ApplicationContext to the lifecycle of the ServletContext and to automate the creation of ApplicationContext. We can use it to define shared beans that can be used across different spring contexts.(Selenium Training )

3. What is View Resolver in Spring?
Answer: ViewResolver implementations are used to resolve the view pages by name. Usually, we configure it in the spring bean configuration file.

For example:
InternalResourceViewResolver is one of the implementations of ViewResolver interface and we are providing the view pages directory and suffix location through the bean properties. So if a controller handler method returns “home”, view resolver will use view page located at /WEB-INF/views/home.jsp.

4. How many types of IOC containers are there in spring?
Answer: BeanFactory: BeanFactory is like a factory class that contains a collection of beans. It instantiates the bean whenever asked for by clients.
ApplicationContext: The ApplicationContext interface is built on top of the BeanFactory interface. It provides some extra functionality on top BeanFactory.(Sap Fico Online Training )

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

6. List some of the benefits of IoC?
Answer:
Some of the benefits of IoC are:
It will minimize the amount of code in your application.
It will make your application easy to test because it doesn’t require any singletons or JNDI lookup mechanisms in your unit test cases.
It promotes loose coupling with minimal effort and least intrusive mechanism.
It supports eager instantiation and lazy loading of the services.(Azure Training )

7. In how many ways can Dependency Injection be done?
Answer:
In general, dependency injection can be done in three ways, namely :
Constructor Injection
Setter Injection
Interface Injection
In Spring Framework, only constructor and setter injections are used.

8. What is the role of the @Required annotation?
Answer: The @Required annotation is used on setter methods, and it indicates that the bean property that has this annotation must be populated at configuration time. Otherwise, the Spring container will throw a BeanInitializationException exception.
Also, @Required differs from @Autowired – as it is limited to a setter, whereas @Autowired is not. @Autowired can be used to wire with a constructor and afield as well, while @Required only checks if the property is set.
Let’s see an example:
public class Person
private String name;
@Required
public void setName(String name)
this.name = name;
Now, the name of the Person bean needs to be set in XML config like this:

9. Can we have multiple Spring configuration files in one project?
Answer:
Yes, in large projects, having multiple Spring configurations is recommended to increase maintainability and modularity.

You can load multiple Java-based configuration files:
@Configuration
@Import({MainConfig.class, SchedulerConfig.class})
public class AppConfig {
Or load one XML file that will contain all other configs:

ApplicationContext context = new ClassPathXmlApplicationContext(“spring-all.xml”);
And inside this XML file you’ll have:

10. What is Spring Boot ?
Answer: Spring Boot is a project that provides a pre-configured set of frameworks to reduce boilerplate configuration so that you can have a Spring application up and running with the smallest amount of code.

11. Explain Spring Beans?
Answer: They are the objects that form the backbone of the user’s application.
Beans are managed by the Spring IoC container.
They are instantiated, configured, wired and managed by a Spring IoC container
Beans are created with the configuration metadata that the users supply to the container. Bean generation.

12. What is the Spring IoC Container?
Answer: Inversion of Control (IoC) is the mechanism to achieve loose-coupling between Objects dependencies. To achieve loose coupling and dynamic binding of the objects at runtime, the objects define their dependencies that are being injected by other assembler objects. Spring IoC container is the program that injects dependencies into an object and makes it ready for our use.

Spring Framework IoC container classes are part of org.springframework.beans, and org.springframework.context packages and provides us different ways to decouple the object dependencies.

Some of the useful ApplicationContext implementations that we use are;

AnnotationConfigApplicationContext: For standalone java applications using annotations based configuration.
ClassPathXmlApplicationContext: For standalone java applications using XML based configuration.
FileSystemXmlApplicationContext: Similar to ClassPathXmlApplicationContext except that the xml configuration file can be loaded from anywhere in the file system.
AnnotationConfigWebApplicationContext and XmlWebApplicationContext for web applications.

13. How many bean scopes are supported by Spring?
Answer: The Spring Framework supports five scopes. They are:
Singleton: This provides scope for the bean definition to a single instance per Spring IoC container.
Prototype: This provides scope for a single bean definition to have any number of object instances.
Request: This provides scope for a bean definition to an HTTP-request.
Session: This provides scope for a bean definition to an HTTP-session.
Global-session: This provides scope for a bean definition to a Global HTTP-session.
The last three are available only if the users use a web-aware ApplicationContext.

14. What are the limitations with auto wiring?
Answer: Following are some of the limitations you might face with auto wiring:
Overriding possibility: You can always specify dependencies using and settings which will override auto wiring.
Primitive data type: Simple properties such as primitives, Strings and Classes can’t be autowired.
Confusing nature: Always prefer using explicit wiring because auto wiring is less precise.

15. What are the different types of Advice?
Answer:
Before: These types of advice execute before the joinpoint methods and are configured using @Before annotation mark.
After returning: These types of advice execute after the joinpoint methods complete executing normally and are configured using @AfterReturning annotation mark.
After throwing: These types of advice execute only if the joinpoint method exits by throwing an exception and are configured using @AfterThrowing annotation mark.
After (finally): These types of advice execute after a joinpoint method, regardless of the method’s exit whether normally or exceptional return and are configured using @After annotation mark.
Around: These types of advice execute before and after a joinpoint and are configured using the @Around annotation mark.