Creating a restful API using SpringBoot || Best example to understand concept in easy way.

Creating a Simple RESTful API

Let's create a simple RESTful API using Spring Boot.

Create a Controller Class:

java

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {
    @GetMapping("/hello")
    public String sayHello() {
        return "Hello, Spring Boot!";
    }
}

Run the Application:

• Restart your application and visit http://localhost:8080/hello 

to see the message "Hello, Spring Boot!".

Database Integration with Spring Data JPA

Configuring the Database: Add the following properties to src/main/resources/application.properties:

properties

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=password
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect

Creating an Entity:

java

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    private String name;
    // Getters and setters
}

Creating a Repository:

java

import org.springframework.data.jpa.repository.JpaRepository;

public interface UserRepository extends JpaRepository<User, Long> {
}

Creating a Service:

java

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;

@Service
public class UserService {
    @Autowired
    private UserRepository userRepository;

    public List<User> getAllUsers() {
        return userRepository.findAll();
    }

    public User saveUser(User user) {
        return userRepository.save(user);
    }
}

Creating a Controller:

java

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;

@RestController
public class UserController {
    @Autowired
    private UserService userService;

    @GetMapping("/users")
    public List<User> getAllUsers() {
        return userService.getAllUsers();
    }

    @PostMapping("/users")
    public User createUser(@RequestBody User user) {
        return userService.saveUser(user);
    }
}

Conclusion

Spring Boot simplifies Java application development, allowing developersto focus on business logic rather than boilerplate code. Its powerful features,

extensive documentation, and active community make it a top choice
for both new and experienced developers. By following this guide,
you'll be well on your way to creating your own Spring Boot applications
and integrating them with various Java technologies.