Here in this article I'm starting with the basics of Spring Boot Rest API Development. This is going to be an introduction to the series of practical hands-on guides in which we would learn Spring-Boot, Rest API and Microservices.

Prerequisites:-

• 1% interest to learn

• Basics of Java

• Basics of Spring & Spring Boot

Create a Spring Boot Project

Lets head-over to https://start.spring.io/ to download the Spring boot project.

Select the build-tool of your choice (Maven/Gradle) and the programming language [Java of course for me :-) ] apart from the Spring Boot version (avoid using Snapshot as they're still in development stage

Then, click on Add dependencies (as highlighted below) on the right hand-side of the page and select "Spring Web" like in the below image

• Spring Boot Starter Web Dependency helps to develop Restful Web-Services and Spring MVC Web Apps.

  • It provides all required dependencies to develop applications. Some of them are

    • Starter JSON

    • Spring Web

    • Spring Web MVC

    • Apache Tomcat Server (WebServer to run our Spring boot Apps)

No Spring without annotations, isn't it ? As expected, let us go through some of the basic annotations which are used everyday in the world of Spring Boot before heading over to the development.

Useful Annotations:-

• @SpringBootApplication - used to define a Spring Boot Application. It is made up of 3 annotations which are

  • @Configuration - Source of bean definitions

  • @EnableAutoConfiguration - auto-configures the bean that is present in the class-path and configures it to run the methods present.

  • @ComponentScan - scans all the packages available in the class-path to find out the beans.

• @RestController - This is used in class level to make it as a request handler and used in RESTful Web Services to handle the requests. It in turn is a combination of 2 annotations which are

  1. @Controller - primarily used to make a java class as a Spring MVC Controller

  2. @ResponseBody - The object returned is automatically serialised into JSON & passed back into the HTTP Response object

• @PathVariable - retrieves the path parameters from a API request and use it in the controller method

• @RequestParam - retrieves the query parameters. I can guess what're you thinking, we will definitely see the differences between this and PathVariable later :)

• @RequestBody - binds the http request bodies to method parameters in Spring MVC.

  • It allows to extract the request body content, such as XML/JSON and map it to the relevant Java object.

  • Internally uses the Spring provided HttpMessageConverter to convert json into java object.

• @ResponseStatus - In order to send a http status in response to the client.

What to expect next:-

Stay tuned for part-2 in which we will go through request-handler methods and start implementing the coding part of Rest-API basics. Please let me know your comments in case of any improvement.

Meanwhile, if you are preparing for Java-Spring Boot developer interviews, then here are a few books from javinpaul & @javarevistited publications

• Grokking the Java Interview: https://gumroad.com/a/181345491/QqjGH

• Grokking the Spring Boot Interview: https://gumroad.com/a/181345491/hrUXKY