Spring Boot ve Spring Data JPA ile Sayfalama

By Cem Dırman On Nov 17, 2020

Bu yazıda Spring Data JPA ile rest servislerde sayfalama üzerinde duracağız. Sayfalama için URL’den hem sayfada listelenecek ürün adetini hem de sayfa numarasını parametre olarak alacağız.

Spring Boot 2.3.6
Java 8
Lombok
Maven
H2

Aşağıdaki bağımlılıklarımızı pom.xml’e ekliyoruz.



                <dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
                <dependency>
			<groupId>com.h2database</groupId>
			<artifactId>h2</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<optional>true</optional>
		</dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-data-jpa</artifactId>

</dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-web</artifactId>

</dependency>

<groupId>com.h2database</groupId>

<scope>runtime</scope>

</dependency>

<groupId>org.projectlombok</groupId>

<artifactId>lombok</artifactId>

</dependency>

Entity



@Entity
@Table(name = "Products")
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Product {

	@Id
	private Long id;
	@Column
	private String name;
	@Column
	private String imageUrl;
	@Column
	private BigDecimal amount;

}

@Entity

@Table(name = "Products")

@Data

@AllArgsConstructor

@NoArgsConstructor

public class Product {

@Id

private Long id;

@Column

private String name;

@Column

private String imageUrl;

@Column

private BigDecimal amount;

}

Controller



@RestController
public class ProductController {

	@Autowired
	private ProductService productService;

	@GetMapping(value = "/products")
	public ResponseEntity<Page<Product>> fetchProducts(
			@RequestParam(required = false, name = "productName") String productName,
			@RequestParam(defaultValue = "0", name = "page") int page,
			@RequestParam(defaultValue = "5", name = "size") int size) {
		return new ResponseEntity<>(productService.getAllProducts(productName, page, size), HttpStatus.OK);
	}

	@GetMapping(value = "/products/{productName}")
	public ResponseEntity<Product> fetchProducts(
			@PathVariable(required = true, name = "productName") String productName) {
		return new ResponseEntity<>(productService.getProductByName(productName), HttpStatus.OK);
	}

}

@RestController

public class ProductController {

@Autowired

private ProductService productService;

@GetMapping(value = "/products")

public ResponseEntity<Page<Product>> fetchProducts(

@RequestParam(required = false, name = "productName") String productName,

@RequestParam(defaultValue = "0", name = "page") int page,

@RequestParam(defaultValue = "5", name = "size") int size) {

return new ResponseEntity<>(productService.getAllProducts(productName, page, size), HttpStatus.OK);

}

@GetMapping(value = "/products/{productName}")

public ResponseEntity<Product> fetchProducts(

@PathVariable(required = true, name = "productName") String productName) {

return new ResponseEntity<>(productService.getProductByName(productName), HttpStatus.OK);

}

Service



@Service
public class ProductService {

	@Autowired
	private ProductRespository productRespository;

	public Page<Product> getAllProducts(String productName, int page, int size) {
		Pageable pageable = createPageable(page, size);
		if (StringUtils.isEmpty(productName)) {
			return productRespository.findAll(pageable);
		}
		return productRespository.findByNameContaining(productName, pageable);
	}

	private Pageable createPageable(int page, int size) {
		Pageable pageable = PageRequest.of(page, size, Sort.by("id"));
		Pageable pageable1 = PageRequest.of(page, size);
		Pageable pageable2 = PageRequest.of(page, size, Direction.ASC, "id");
		return pageable;
	}

	public Product getProductByName(String productName) {
		return productRespository.findByNameIgnoreCase(productName);
	}

}

@Service

public class ProductService {

@Autowired

private ProductRespository productRespository;

public Page<Product> getAllProducts(String productName, int page, int size) {

Pageable pageable = createPageable(page, size);

if (StringUtils.isEmpty(productName)) {

return productRespository.findAll(pageable);

}

return productRespository.findByNameContaining(productName, pageable);

}

private Pageable createPageable(int page, int size) {

Pageable pageable = PageRequest.of(page, size, Sort.by("id"));

Pageable pageable1 = PageRequest.of(page, size);

Pageable pageable2 = PageRequest.of(page, size, Direction.ASC, "id");

return pageable;

}

public Product getProductByName(String productName) {

return productRespository.findByNameIgnoreCase(productName);

}

Repository katmanına göndereceğimiz Pageable objesini burada hazırlıyoruz. Bu class Spring data’nın sunduğu bir interface. PageRequest ise Pageable’dan kalıtılmış bir class ve gördüğümüz üzere overload edilmiş üç metoda sahip. Controller katmanından aldığımız sayfa numarasını ve listelenecek ürün adetini ve isterseniz sıralamanın nasıl olmasını gerektiğini bu metodlara verebilirsiniz.

Respository



@Repository
public interface ProductRespository extends PagingAndSortingRepository<Product, Long> {

	Page<Product> findAll(Pageable pageable);

	Page<Product> findByNameContaining(String productName, Pageable pageable);

	Product findByNameIgnoreCase(String productName);

}

@Repository

public interface ProductRespository extends PagingAndSortingRepository<Product, Long> {

Page<Product> findAll(Pageable pageable);

Page<Product> findByNameContaining(String productName, Pageable pageable);

Product findByNameIgnoreCase(String productName);

}

Burada methodun dönüş tipi Page. Bu interface aşağıdaki yorum satırında da söylediği gibi içerdiği liste hakkında bilgi verir. Bazı faydalı bilgiler aynı zamanda Slice‘da da mevcut. Slice’dan extends edildiği zaten gözüküyor, ben uzatmamak için buraya kodu eklemeyeceğim fakat incelenmesinde fayda var.



/**
 * A page is a sublist of a list of objects. It allows gain information about the position of it in the containing
 * entire list.
 *
 * @param <T>
 * @author Oliver Gierke
 */
public interface Page<T> extends Slice<T> {

	static <T> Page<T> empty() {
		return empty(Pageable.unpaged());
	}

	static <T> Page<T> empty(Pageable pageable) {
		return new PageImpl<>(Collections.emptyList(), pageable, 0);
	}

	int getTotalPages();

	long getTotalElements();

	<U> Page<U> map(Function<? super T, ? extends U> converter);
}

/**

* A page is a sublist of a list of objects. It allows gain information about the position of it in the containing

* entire list.

* @param <T>

* @author Oliver Gierke

public interface Page<T> extends Slice<T> {

static <T> Page<T> empty() {

return empty(Pageable.unpaged());

}

static <T> Page<T> empty(Pageable pageable) {

return new PageImpl<>(Collections.emptyList(), pageable, 0);

}

int getTotalPages();

long getTotalElements();

<U> Page<U> map(Function<? super T, ? extends U> converter);

}

Son olarak ise listelemek için kayıt gerektiği için uygulama ayağa kalkerken tabloya aşağıdaki gibi kayıt atabiliriz.



@SpringBootApplication
public class RestservicePaginationApplication {

	@Autowired
	private ProductRespository respository;

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

	@PostConstruct
	private void insertProducts() {
		List<Product> productList = new ArrayList<>();

		for (int i = 1; i <= 30; i++) {
			String productName = "Product".concat(" " + i);
			productList
					.add(new Product(new Long(i), productName,
                                      "https://bilisim.io/".concat(productName), getAmount()));
		}
		respository.saveAll(productList);
	}

	private BigDecimal getAmount() {
		double amount = ThreadLocalRandom.current().nextDouble(55, 500);
		return BigDecimal.valueOf(amount);
	}

}

@SpringBootApplication

public class RestservicePaginationApplication {

@Autowired

private ProductRespository respository;

public static void main(String[] args) {

SpringApplication.run(RestservicePaginationApplication.class, args);

}

@PostConstruct

private void insertProducts() {

List<Product> productList = new ArrayList<>();

for (int i = 1; i <= 30; i++) {

String productName = "Product".concat(" " + i);

productList

.add(new Product(new Long(i), productName,

"https://bilisim.io/".concat(productName), getAmount()));

}

respository.saveAll(productList);

}

private BigDecimal getAmount() {

double amount = ThreadLocalRandom.current().nextDouble(55, 500);

return BigDecimal.valueOf(amount);

}

http://localhost:8080/products

ya da

http://localhost:8080/products?page=0&size=5



// 

{
  "content": [
    {
      "id": 1,
      "name": "Product 1",
      "imageUrl": "https://bilisim.io/Product_1",
      "amount": 178.75
    },
    {
      "id": 2,
      "name": "Product 2",
      "imageUrl": "https://bilisim.io/Product_2",
      "amount": 487.33
    },
    {
      "id": 3,
      "name": "Product 3",
      "imageUrl": "https://bilisim.io/Product_3",
      "amount": 224.34
    },
    {
      "id": 4,
      "name": "Product 4",
      "imageUrl": "https://bilisim.io/Product_4",
      "amount": 58.25
    },
    {
      "id": 5,
      "name": "Product 5",
      "imageUrl": "https://bilisim.io/Product_5",
      "amount": 74.59
    }
  ],
  "pageable": {
    "sort": {
      "sorted": true,
      "unsorted": false,
      "empty": false
    },
    "offset": 0,
    "pageNumber": 0,
    "pageSize": 5,
    "unpaged": false,
    "paged": true
  },
  "totalPages": 6,
  "totalElements": 30,
  "last": false,
  "numberOfElements": 5,
  "first": true,
  "sort": {
    "sorted": true,
    "unsorted": false,
    "empty": false
  },
  "size": 5,
  "number": 0,
  "empty": false
}

{

"content": [

{

"id": 1,

"name": "Product 1",

"imageUrl": "https://bilisim.io/Product_1",

"amount": 178.75

{

"id": 2,

"name": "Product 2",

"imageUrl": "https://bilisim.io/Product_2",

"amount": 487.33

{

"id": 3,

"name": "Product 3",

"imageUrl": "https://bilisim.io/Product_3",

"amount": 224.34

{

"id": 4,

"name": "Product 4",

"imageUrl": "https://bilisim.io/Product_4",

"amount": 58.25

{

"id": 5,

"name": "Product 5",

"imageUrl": "https://bilisim.io/Product_5",

"amount": 74.59

}

"pageable": {

"sort": {

"sorted": true,

"unsorted": false,

"empty": false

"offset": 0,

"pageNumber": 0,

"pageSize": 5,

"unpaged": false,

"paged": true

"totalPages": 6,

"totalElements": 30,

"last": false,

"numberOfElements": 5,

"first": true,

"sort": {

"sorted": true,

"unsorted": false,

"empty": false

"size": 5,

"number": 0,

"empty": false

}

https://github.com/cemdrman/restservice-pagination/tree/master

Faydalı olması dileğiyle.