Introduction:
In this article will look into how to create a REST API using HTTP methods for Create and Retrieve operations in Spring Boot along with MYSQL database. Spring Boot is an open source Java-based framework to build enterprise spring applications. . 

Overview: 

Create MYSQL database using WampServer.
Download WampServer install and Run-> go to phpMyAdmin and click.  

Open localhost/phpmyadmin/ 

Create Database Name is “hostel”.

Crate Table in hostel Database. Table Name is states with number of fields/Column.

Create Table column name, which is show in image.

Create the Spring Boot Project from STS-4:
It will write project name, group, artifact, version, description, package etc. 

 

Create Entity model class. 

• Create the States model class to map with the States table.
• @Entity is used to annotate that the class is an entity in the database.
• @Table is used to annotate name of table in the database.
• @id is used to reference that widget to your java file and access it from java file.
• @GeneratedValue is used to generation strategies for the values of primary keys.

Create JPA Data Repository. 

• Create StatsRepository Repository interface extending JPA Repository.
• There are not need writing any SQL/MySql etc query.
• @Repository annotation is used to indicate that the class provides the mechanism for storage, retrieval, search, and update and delete operation on objects.

• Create StateService service class to code the business logic and it acts as a middle layer between repository and controller class.
• @Service annotation is a specialization of @Component annotation. Spring Service annotation can be applied only to classes. It is used to mark the class as a service provider.
• @Transactional StateService annotate methods are executed in transactions.
  Example:
  @Transactional(readOnly = false, rollbackFor={Throwable.class, Exception.class}, propagation = Propagation.SUPPORTS)
• @Autowired annotation is used for automatic dependency injection. Spring framework is built on dependency injection and we inject the class dependencies through spring bean configuration file.

Create Rest Controllers class. 

• Create Rest StateController Controller class which contains all REST API endpoints for Create and Retrieve operations.
• @RestController annotation was introduced in Spring 4.0 to simplify the creation of REST web services. It's a convenience annotation that combines @Controller and @ResponseBody– which eliminates the need to annotate every request handling method of the controller class with the @ResponseBody annotation.

Run the Project:
Write click to project and Run as->Spring boot App, it will check console to run project success and check running port.  

Testing using Postman.
Execute GET Request method to add a States to the Database. 

 

Video Link for watching How to build API.