Spring Boot Integration With PostgreSQL as a Maven Project

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

@Entity 
@Table(name = "geek_author")
public class geek_author {
    @Id
    @GeneratedValue(strategy=GenerationType.SEQUENCE)
    private Integer author_id;

    private String author_name;

    private String email_id;

    public Integer getAuthor_id() {
        return author_id;
    }

    public void setAuthor_id(Integer author_id) {
        this.author_id = author_id;
    }

    public String getAuthor_name() {
        return author_name;
    }

    public void setAuthor_name(String author_name) {
        this.author_name = author_name;
    }

    public String getEmail_id() {
        return email_id;
    }

    public void setEmail_id(String email_id) {
        this.email_id = email_id;
    }    
    
}

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

import com.gfg.postgresql.model.geek_author;

@Repository
public interface AuthorRepository extends JpaRepository<geek_author, Long>{

}

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import com.gfg.postgresql.model.geek_author;
import com.gfg.postgresql.repository.AuthorRepository;

// This means that this 
// class is a Controller
@Controller    

// This means URL's start with /geek (after Application path)
@RequestMapping(path="/geek") 
public class AuthorController {
  
    // This means to get the bean called geekuserRepository
    // Which is auto-generated by Spring, we will use it
    // to handle the data
    @Autowired 
    private AuthorRepository authorRepository;

    // Map ONLY POST Requests
    @PostMapping(path="/addauthor") 
    public @ResponseBody String addAuthors (@RequestParam String author_name
            , @RequestParam String email_id) {
      
        // @ResponseBody means the returned String
        // is the response, not a view name
        // @RequestParam means it is a parameter
        // from the GET or POST request      
        geek_author geekAuthor = new geek_author();
        
        geekAuthor.setAuthor_name(author_name);
        geekAuthor.setEmail_id(email_id);
        authorRepository.save(geekAuthor);
        return "Details got Saved";
    }

    @GetMapping(path="/authors")
    public @ResponseBody Iterable<geek_author> getAllAuthors() {
        // This returns a JSON or 
        // XML with the Book
        return authorRepository.findAll();
    }
}

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

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