Spring Boot - CRUD操作

public interface CrudRepository<T,ID> extends Repository<T,ID>

public interface StudentRepository extends CrudRepository<Student, Integer>
{
}

public interface BookDAO extends JpaRepository 
{
}

package com.learnfk.model;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
//mark class as an Entity 
@Entity
//defining class name as Table name
@Table
public class Books
{
  //Defining book id as primary key
  @Id
  @Column
  private int bookid;
  @Column
  private String bookname;
  @Column
  private String author;
  @Column
  private int price;
  public int getBookid() 
  {
    return bookid;
  }
  public void setBookid(int bookid) 
  {
    this.bookid = bookid;
  }
  public String getBookname()
  {
    return bookname;
  }
  public void setBookname(String bookname) 
  {
    this.bookname = bookname;
  }
  public String getAuthor() 
  {
    return author;
  }
  public void setAuthor(String author) 
  {
    this.author = author;
  }
  public int getPrice() 
  {
    return price;
  }
  public void setPrice(int price) 
  {
    this.price = price;
  }
}

package com.learnfk.controller;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import com.learnfk.model.Books;
import com.learnfk.service.BooksService;
//mark class as Controller
@RestController
public class BooksController 
{
  //autowire the BooksService class
  @Autowired
  BooksService booksService;
  //creating a get mapping that retrieves all the books detail from the database 
  @GetMapping("/book")
  private List getAllBooks() 
  {
    return booksService.getAllBooks();
  }
  //creating a get mapping that retrieves the detail of a specific book
  @GetMapping("/book/{bookid}")
  private Books getBooks(@PathVariable("bookid") int bookid) 
  {
    return booksService.getBooksById(bookid);
  }
  //creating a delete mapping that deletes a specified book
  @DeleteMapping("/book/{bookid}")
  private void deleteBook(@PathVariable("bookid") int bookid) 
  {
    booksService.delete(bookid);
  }
  //creating post mapping that post the book detail in the database
  @PostMapping("/books")
  private int saveBook(@RequestBody Books books) 
  {
    booksService.saveOrUpdate(books);
    return books.getBookid();
  }
  //creating put mapping that updates the book detail 
  @PutMapping("/books")
  private Books update(@RequestBody Books books) 
  {
    booksService.saveOrUpdate(books);
    return books;
  }
}

package com.learnfk.service;
import java.util.ArrayList;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.learnfk.model.Books;
import com.learnfk.repository.BooksRepository;
//defining the business logic
@Service
public class BooksService 
{
  @Autowired
  BooksRepository booksRepository;
  //getting all books record by using the method findaAll() of CrudRepository
  public List<Books> getAllBooks() 
  {
    List<Books> books = new ArrayList<Books>();
    booksRepository.findAll().forEach(books1 -> books.add(books1));
    return books;
  }
  //getting a specific record by using the method findById() of CrudRepository
  public Books getBooksById(int id) 
  {
    return booksRepository.findById(id).get();
  }
  //saving a specific record by using the method save() of CrudRepository
  public void saveOrUpdate(Books books) 
  {
    booksRepository.save(books);
  }
  //deleting a specific record by using the method deleteById() of CrudRepository
  public void delete(int id) 
  {
    booksRepository.deleteById(id);
  }
  //updating a record
  public void update(Books books, int bookid) 
  {
    booksRepository.save(books);
  }
}

package com.learnfk.repository;
import org.springframework.data.repository.CrudRepository;
import com.learnfk.model.Books;
//repository that extends CrudRepository
public interface BooksRepository extends CrudRepository
{
}

spring.datasource.url=jdbc:h2:mem:books_data
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
#enabling the H2 console
spring.h2.console.enabled=true

package com.learnfk;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class SpringBootCrudOperationApplication 
{
  public static void main(String[] args) 
  {
    SpringApplication.run(SpringBootCrudOperationApplication.class, args);
  }
}

{
    "bookid": "5433",
    "bookname": "Core and Advance Java",
    "author": "R. Nageswara Rao",
    "price": "800"
} 

{
    "bookid": "0982",
    "bookname": "Programming with Java",
    "author": "E. Balagurusamy",
    "price": "350"
} 
{
    "bookid": "6321",
    "bookname": "Data Structures and Algorithms in Java",
    "author": "Robert Lafore",
    "price": "590"
} 
{
    "bookid": "5433",
    "bookname": "Effective Java",
    "author": "Joshua Bloch",
    "price": "670"
}

{
    "bookid": "6321",
    "bookname": "Data Structures and Algorithms in Java",
    "author": "Robert Lafore",
    "price": "500"
}