Spring interview questions and answer : Spring Boot has been an important part of the Spring ecosystem since its inception. With its capacity to auto-configure, this project makes our lives a lot easier.
We’ll go over some of the most typical Spring Boot questions that may come up during a job interview in this lesson.
Spring interview questions and answer
1.What Is a Spring Boot, and What Are Its Characteristics?
Ans: Spring Boot is a quick application development framework built on top of the Spring Framework. Spring Boot is one of the most popular technologies in the Java ecosystem today, thanks to its auto-configuration and inbuilt application server support, as well as its vast documentation and community support.
Here are a few key characteristics:
- Starters – a set of dependency descriptors that can be used to quickly incorporate relevant dependencies.
- Auto-configuration Is a method of automatically configuring an application based on the classpath dependencies.
- Actuator – for features like monitoring that are ready for production.
- Safety and security
Logging is number five.
2.How Do You Tell the Difference Between a Spring and a Spring Boot?
Ans: The Spring Framework has a number of features that make web application development easier. Dependency injection, data binding, aspect-oriented programming, data access, and other features are among them.
Spring has become increasingly complex over time, and the amount of configuration required for such an application can be overwhelming. Spring Boot comes in helpful here because it makes setting up a Spring application a breeze.
Essentially, while Spring is agnostic, Spring Boot takes an agnostic approach to the platform and libraries, allowing us to get up and running quickly.
Here are two of the most significant advantages that Spring Boot provides:
- Configure apps automatically depending on artifacts found on the classpath
- Include non-functional features that are prevalent in production systems, such as security and health checks.
3.How Do We Set Up a Maven Spring Boot Application?
Ans: Spring Boot can be included in a Maven project just like any other library. The best approach is to inherit from the spring-boot-starter-parent project and specify Spring Boot starter dependencies. This allows us to reuse Spring Boot’s default settings in our project.
It’s convenient to use the beginning parent project, but it’s not always possible. For example, if our firm mandates that all projects inherit from a standard POM, we can still use a custom parent to benefit from Spring Boot’s dependency management.
4.What Is Spring Initializr and How Does It Work?
Ans: Spring Initializr is a quick and easy way to get a Spring Boot project started.
We can go to the Spring Initializr site and select a dependency management tool (Maven or Gradle), a language (Java, Kotlin, or Groovy), a packaging scheme (Jar or War), a version, and dependencies, before downloading the project.
This builds a skeleton project for us, saving us time in the setup process so we can focus on implementing business logic.
Even when we utilize our IDE’s new project wizard to create a Spring Boot project (such as STS or Eclipse with STS plugin), Spring Initializr is used behind the scenes.
5.Are There Any Spring Boot Starters Available?
Ans: Each starter serves as a one-stop-shop for all of the Spring technologies that we require. Other essential dependencies are then dragged in and managed in a consistent manner.
The org. spring framework. boot group contains all starters, and their names begin with spring-boot-starter-. This naming style makes it simple to locate beginnings, particularly when using IDEs that allow you to search for dependencies by name.
There are more than 50 starters available at the time of this writing. We’ll go over the most popular ones here:
- spring-boot-starter: the core starter, which includes auto-configuration, logging, and YAML support.
- spring-boot-starter-aop: for Spring AOP and AspectJ aspect-oriented programming.
- spring-boot-starter-data-jpa: for Hibernate and Spring Data JPA.
- spring-boot-starter-security: for implementing Spring Security.
- spring-boot-starter-test: this command is used to test Spring Boot apps.
- spring-boot-starter-web: for leveraging Spring MVC to create web applications, including RESTful ones.
6.How Can I Turn Off a Specific Auto-Configuration?
Ans: If we wish to disable a specific auto-configuration, we can use the @EnableAutoConfiguration annotation’s exclude attribute.
7.How do you tell an auto-configuration to back off when a bean is present?
Ans: The @ConditionalOnMissingBean annotation can be used to tell an auto-configuration class to stop when a bean already exists.
The following are the most notable features of this annotation:
- quantity – the number of beans to inspect
- name – the names of the beans that will be examined
8.How to Use Jar and War Files to Deploy Spring Boot Web Applications
Ans: A web application is often packaged as a WAR file and then deployed to an external server. As a result, we can run numerous programs on the same server. This was a fantastic technique to preserve resources when CPU and memory were scarce.
However, times have changed. Now that computer hardware is very inexpensive, the focus has shifted to server configuration. A minor misconfiguration of the server during deployment can have disastrous repercussions.
9.What Are Some External Configuration Sources?
Ans: External configuration is supported by Spring Boot, allowing us to run the same application in different settings. To specify configuration properties, we can utilize properties files, YAML files, environment variables, system properties, and command-line option arguments.
The @Value annotation, a bound object via the @ConfigurationProperties annotation, or the Environment abstraction can then be used to access those properties.
10.What Are Integration Tests and How Do You Write Them?
Ans: An ApplicationContext is required for executing integration tests for a Spring application.
Spring Boot provides a specific annotation for testing called @SpringBootTest to make our lives easier. The classes attribute of this annotation specifies the configuration classes that will be used to generate an ApplicationContext.
Spring Boot looks for the primary configuration class if the classes attribute isn’t set. The search begins with the test package and continues until a class annotated with @SpringBootApplication or @SpringBootConfiguration is found.
11.Is it better to use properties or YAML to configure a Spring Boot project?
Ans: YAML has a number of advantages over property files:
- Improved readability and clarity
- Specifically designed for hierarchical configuration data, which is also presented in a more legible style.
- Maps, lists, and scalar types are all supported.
- Multiple profiles can be stored in the same file (since Spring Boot 2.4.0, this is possible for properties files too)
- However, due to its indentation requirements, writing it might be tricky and error-prone.
12.What Is the Purpose of Spring Profiles?
Ans: We often deal with several environments when designing enterprise apps, such as Dev, QA, and Prod. These environments have various setup attributes.
For example, Dev might have an inbuilt H2 database, but Prod might have a proprietary Oracle or DB2 database. Even though the DBMS is the same in all situations, the URLs will almost certainly differ.
Spring provides profiles to assist segregate the setup for each environment, making this simple and clean. Instead of keeping the properties programmatically, they can be kept in distinct files like application-dev. properties and application-prod. properties. The default application.properties use spring.profiles.active to point to the currently active profile, ensuring that the correct configuration is picked up.
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This article Spring interview questions and answer covered some of the most important Spring Boot questions that may come up during a technical interview.