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Spring Initializer is a web-based tool and a command-line interface that simplifies the process of creating and configuring Spring Boot applications. Spring Boot is a framework that makes it easier to set up and develop Java applications by providing a wide range of default configurations and sensible defaults. Spring Initializer allows developers to quickly generate a new Spring Boot project with the necessary dependencies, configuration files, and directory structure based on their requirements.

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Spring Data REST isn’t recommended for real-world applications due to its direct exposure of database entities as REST services. When crafting RESTful services, the primary concerns are the domain model and consumer experience. However, Spring Data REST overlooks these factors and directly reveals entities. Therefore, it’s recommended to utilize Spring Data REST primarily during the project’s initial stages.

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Both methods are used to start a Spring Boot application. SpringApplication.run(Class, String[]) allows you to pass the primary application class along with command-line arguments, whereas SpringApplication.run() can be used without specifying the primary class if it’s called from within the primary class itself.

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Spring Boot provides the @RestController annotation, which combines the @Controller and @ResponseBody annotations. This allows you to create RESTful APIs easily by writing methods that return domain objects directly, which are then automatically serialized to JSON or XML. Spring Boot also includes built-in support for content negotiation and exception handling in REST APIs.

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Spring Boot Actuator is a set of production-ready features that help in monitoring and managing Spring Boot applications. It provides endpoints for gathering application metrics, health checks, application environment details, and more. Actuator endpoints are crucial for monitoring application health and performance in production environments.

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Spring Boot allows you to externalize configuration properties using various property sources such as property files, YAML files, environment variables, and command-line arguments. Properties defined in these sources can be accessed in Spring components using the @Value annotation or through the Environment object.

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Spring Boot Starter modules are a set of pre-configured dependencies that facilitate the setup of specific functionalities. Each starter module includes a set of common dependencies and configuration to simplify development. For example, the “spring-boot-starter-web” module includes dependencies and configuration for building web applications.

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Auto-configuration in Spring Boot refers to the mechanism by which the framework automatically onfigures beans based on the classpath and the presence of specific dependencies. Spring Boot’s auto-configuration feature helps developers avoid writing a significant amount of boilerplate code by providing sensible defaults and configurations for various Spring components.

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The @Transactional annotation in Spring Boot is used to indicate that a method or a class should be managed within a transactional context. Transactions are used to ensure the integrity and consistency of data in a database. When a method is annotated with @Transactional, Spring Boot automatically handles the creation, management, and completion of database transactions.

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We can address this issue using three main approaches:

1. Custom Error Controller: In this method, you will need to implement the ErrorController interface provided by the Spring Framework. By overriding the getErrorPath() method, you can define a custom path to handle specific errors that occur. This allows you to have more control over how errors are handled and presented.
2. Displaying a Custom Error Page: To implement this approach, you’ll create an html page and place it in the src/main/resources/templates directory. Spring Boot’s BasicErrorController will automatically utilize this file as the default error page. This method provides the flexibility to design and display error messages according to your requirements.
3. Disabling the Whitelabel Error Page: The simplest method is to disable the whitelabel error page. You can achieve this by setting the error.whitelabel.enabled property to false in the application.properties file. By doing so, the default generic error page provided by Spring Boot will not be displayed, giving you the option to handle errors in a more customized manner.

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Bootstrapping refers to the process of initializing and configuring a Spring application with minimal manual configuration. Spring Boot is an extension of the Spring framework that aims to simplify the development of Java applications by providing default settings, sensible defaults, and automatic configuration based on convention over configuration principles.

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The latest version of spring boot is 2.6.0 that offers various dependency upgrades, Java 15 support and much more.

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In a Spring Boot application, you can check the environment properties using the Environment object provided by the Spring framework. This object gives you access to various properties and configuration settings that your application uses.

Here’s how you can check environment properties in a Spring Boot application:

1. Inject Environment Object: In your Spring component (such as a controller, service, or configuration class), you can inject the Environment object using Spring’s dependency injection mechanism.
2. Using @Value Annotation: You can also use the @Value annotation to directly inject specific properties into your components
3. Accessing Application Properties File: Spring Boot applications typically use a properties file (like properties or application.yml) to store configuration. You can define properties in this file and access them using the methods mentioned above.

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An IOC (Inversion of Control) container is a software design pattern used in computer programming. The main purpose of an IOC container is to manage the instantiation and lifecycle of objects in a program by “inverting control” from the program itself to the container.

In traditional programming, the application code explicitly creates and manages instances of various classes and their dependencies. With an IOC container, this responsibility is shifted to the container itself. The container keeps track of the various classes and their dependencies, and it provides a way to request instances of these classes whenever needed.

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Some of the basic annotations provided by Spring Boot are:

• @SpringBootApplication
• @Controller
• @RestController
• @RequestMapping
• @Autowired
• @Component
• @Repository
• @Configuration
• @EnableAutoConfiguration

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In Spring Boot, both @RestController and @Controller are used to create components that handle incoming HTTP requests. However, they serve slightly different purposes:

• @Controller: The @Controllerannotation is used to define a class as a Spring MVC controller. It is typically used for creating controllers that handle the presentation layer of a web application. These controllers are responsible for processing requests, interacting with the model, and returning a view to be rendered on the client side. In a @Controller class, methods that handle different URL mappings return the name of the view to be displayed.
• @RestController: The @RestControllerannotation, on the other hand, is used to define a class as a Spring MVC controller that specializes in handling RESTful APIs. Unlike @Controller, @RestController methods don’t return views. Instead, they directly return data (usually in JSON or XML format) that gets serialized and sent as a response to the client. This annotation is suitable for building APIs where the response is not HTML-based but data-driven.

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Spring Boot provides features like embedded web servers, auto-configuration, and production-ready monitoring to simplify the development, deployment, and management of microservices. It also supports building RESTful APIs, which is a common communication pattern between microservices.

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Spring Cloud is a set of tools and libraries that provides support for building and deploying distributed systems and microservices-based applications. It offers solutions for service discovery, configuration management, load balancing, and more.

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Microservices can communicate using various protocols such as HTTP/REST, messaging queues, and service discovery mechanisms (e.g., Netflix Eureka). Spring Cloud provides libraries and tools to simplify these communication patterns.

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Eureka is a service discovery server that allows microservices to register themselves and discover other services. It helps in dynamic scaling, load balancing, and failure recovery in a microservices environment.