Spring Boot

Introduction to Spring Boot

What is Spring Boot?

Spring Boot is an open source Java-based framework used to create a Micro Service. Spring Boot provides a good platform for Java developers to develop a stand-alone and production-grade spring application that you can just run. You can get started with minimum configurations without the need for an entire Spring configuration setup. We need to understand what is Spring framework before go further about Spring Boot.

Spring framework is an open source Java platform that provides comprehensive infrastructure support for developing robust Java applications very easily and very rapidly.Basically Spring is a framework for dependency-injection which is a pattern that allows to build very decoupled systems.

Over the years spring has become more and more complex as new functionalities have been added. Just visit the page-https://spring.io/projects and we will see all the spring projects we can use in our application for different functionalities. If one has to start a new spring project we have to add build path or add maven dependencies, configure application server, add spring configuration . So a lot of effort is required to start a new spring project as we have to currently do everything from scratch. Spring Boot is the solution to this problem. Spring boot has been built on top of existing spring framework. Using spring boot we avoid all the boilerplate code and configurations that we had to do previously. Spring boot thus helps us use the existing Spring functionalities more robustly and with minimum efforts.

Goals of Spring Boot:

To avoid complex XML configuration in Spring
To develop a production ready Spring applications in an easier way
To reduce the development time and run the application independently
Offer an easier way of getting started with the application

Features of Spring Boot:

It provides a flexible way to configure Java Beans, XML configurations, and Database Transactions.
It provides a powerful batch processing and manages REST endpoints.
In Spring Boot, everything is auto configured; no manual configurations are needed.It sets up your application based on the surrounding environment, as well as hints what the developers provide.
It offers annotation-based spring application
Eases dependency management
It includes Embedded Servlet Container
Literally, it's completely standalone. Hence, you don’t need to deploy your application to a web server or any special environment. Your only task is to click on the button or give out the run command, and it will start.
It is Opinionated. This means that the framework chooses how to things for itself. This is the point where a lot of people says "wait a minute, I do not want to participate in it." Here I encourage you to wait for a second and hold your judgment for now, because, actually, it can be a good thing.

Let's examine important and essential features more closely:

Intelligent Auto-Configuration

The intelligent auto-configuration attempts to auto-configure your application based on what dependencies you added. It is contextually aware and smart. Let’s see an example according to a database feature.

If you add a dependency to the pom.xml, which relates to a database, the framework assumes that you probably would like to use a database. Then, it auto-configures your application for database access.Furthermore, if the dependency appears for a very specific database, for example, Oracle or MySQL. It can make a more certain assumption and probably will configure that specific database access what you exactly need.

To set up auto-configuration is extremely effortless. You only need to add the @EnableAutoConfiguration annotation to your Spring Boot application.

Observe the following code for better understanding:

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;

@EnableAutoConfiguration
public class DemoApplication {
   public static void main(String[] args) {
      SpringApplication.run(DemoApplication.class, args);
   }
}

Being Standalone

You may think that running a Java application is easy — you simply give out the run command and everything works. To be honest, it is not that simple.

The Process of Starting a Java-Based Web Application:

First of all, you need to package your application.
Choose which type of web servers you want to use and download it. They are a lot of different solutions out there.
You need to configure that specific web server.
After that, you must organize the deployment process and start your web server.

With Spring Boot, you need the following process:

Package your application
Run it with some simple command like java -jar my-application.jar

Really, it's that simple.

Spring Boot takes care of the rest by starting and configuring an embedded web server and deploys your application there.

Opinionated

If you write Java applications, you have tons of choices, starting from the web, logging, collection framework, and the build tool you use.Despite this, in the most cases, the developers use the same most popular libraries. All that the Spring Boot does is that it loads and configures them in the most standard way. Hence, the developers don’t need to spend a lot of time to configure up the same thing over and over again.

@SpringBootApplication annotation:

The entry point of the Spring Boot Application is the class contains this annotation. This class should have the main method to run the Spring Boot application. This annotation includes Auto- Configuration, Component Scan, and Spring Boot Configuration. If you added @SpringBootApplication annotation to the class, you do not need to add the @EnableAutoConfiguration, @ComponentScan and @SpringBootConfiguration annotation. The @SpringBootApplication annotation includes all other annotations.

Observe the following code for a better understanding:

mport org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {
   public static void main(String[] args) {
      SpringApplication.run(DemoApplication.class, args);
   }
}

@ComponentScan annotation:

Spring Boot application scans all the beans and package declarations when the application initializes. You need to add the @ComponentScan annotation for your class file to scan your components added in your project.