Java Quarkus ile REST API'leri Oluşturma: Yüksek Performanslı, Reaktif ve Bulut Yerel Kılavuzu
Modern kurumsal yazılım mühendisliğinde RESTful API’ler oluşturmak, arka uç sistem geliştirmenin temel taşıdır. Onlarca yıldır Java geliştiricileri Spring Boot veya Jakarta EE gibi geleneksel mimarilere güvendi.
Karşınızda Quarkus—OpenJDK HotSpot ve GraalVM için özel olarak tasarlanmış Supersonic Subatomic Java mimarisi.
1. Java REST API’leri için Neden Quarkus Tercih Edilmeli? A. RESTEasy Reaktif Paradigması B. Yapılandırmasız Dev Services ve Canlı Kodlama 2. Quarkus REST API Mimarisi 3. Proje Başlatma ve Bağımlılıklar mvn io.quarkus.platform:quarkus-maven-plugin:3.15.0:create \ -DprojectGroupId=com.ghaznix.api \ -DprojectArtifactId=quarkus-product-api \ -DclassName="com.ghaznix.api.ProductResource" \ -Dpath="/api/products" \ -Dextensions="resteasy-reactive-jackson,hibernate-orm-panache,jdbc-postgresql,hibernate-validator,smallrye-openapi" 4. Uygulama Özelliklerini Yapılandırma # Application Configuration quarkus.application.name=quarkus-product-api quarkus.http.port=8080 # Database Configuration (Dev Services will override in dev mode automatically) quarkus.datasource.db-kind=postgresql quarkus.datasource.username=postgres quarkus.datasource.password=secret quarkus.datasource.jdbc.url=jdbc:postgresql://localhost:5432/product_db # Hibernate ORM Configuration quarkus.hibernate-orm.database.generation=drop-and-create quarkus.hibernate-orm.log.sql=true # Swagger UI & OpenAPI Path quarkus.swagger-ui.always-include=true quarkus.swagger-ui.path=/swagger-ui 5. Etki Alanı Modeli ve Panache ile Active Record package com.ghaznix.api; import io.quarkus.hibernate.orm.panache.PanacheEntity; import jakarta.persistence.Column; import jakarta.persistence.Entity; import jakarta.persistence.Table; import jakarta.validation.constraints.Min; import jakarta.validation.constraints.NotBlank; import jakarta.validation.constraints.NotNull; import java.math.BigDecimal; import java.util.List; @Entity @Table(name = "products") public class Product extends PanacheEntity { @NotBlank(message = "Product name cannot be blank") @Column(nullable = false) public String name; @Column(length = 1000) public String description; @NotNull(message = "Price is required") @Min(value = 0, message = "Price must be non-negative") @Column(nullable = false) public BigDecimal price; @Column(nullable = false) public Integer stockQuantity; public String category; // Static Finder Utility Methods powered by Panache public static List<Product> findByCategory(String category) { return list("category", category); } public static List<Product> findAvailableProducts() { return list("stockQuantity > 0"); } } 6. Üretim Seviyesinde REST Uç Noktaları Oluşturma package com.ghaznix.api; import io.quarkus.panache.common.Page; import io.quarkus.panache.common.Sort; import jakarta.transaction.Transactional; import jakarta.validation.Valid; import jakarta.ws.rs.*; import jakarta.ws.rs.core.MediaType; import jakarta.ws.rs.core.Response; import org.eclipse.microprofile.openapi.annotations.Operation; import org.eclipse.microprofile.openapi.annotations.responses.APIResponse; import org.eclipse.microprofile.openapi.annotations.tags.Tag; import java.net.URI; import java.util.List; @Path("/api/products") @Produces(MediaType.APPLICATION_JSON) @Consumes(MediaType.APPLICATION_JSON) @Tag(name = "Product REST API", description = "Operations for managing catalog products") public class ProductResource { @GET @Operation(summary = "Get all products with pagination") @APIResponse(responseCode = "200", description = "List of products retrieved successfully") public List<Product> getAllProducts( @QueryParam("page") @DefaultValue("0") int pageIndex, @QueryParam("size") @DefaultValue("10") int pageSize, @QueryParam("sort") @DefaultValue("name") String sortBy) { return Product.findAll(Sort.by(sortBy)) .page(Page.of(pageIndex, pageSize)) .list(); } @GET @Path("/{id}") @Operation(summary = "Get product by ID") @APIResponse(responseCode = "200", description = "Product details found") @APIResponse(responseCode = "404", description = "Product not found") public Product getProductById(@PathParam("id") Long id) { Product product = Product.findById(id); if (product == null) { throw new NotFoundException("Product with ID " + id + " does not exist."); } return product; } @POST @Transactional @Operation(summary = "Create a new product") @APIResponse(responseCode = "201", description = "Product created successfully") @APIResponse(responseCode = "400", description = "Invalid request payload") public Response createProduct(@Valid Product product) { product.persist(); return Response.created(URI.create("/api/products/" + product.id)) .entity(product) .build(); } @PUT @Path("/{id}") @Transactional @Operation(summary = "Update an existing product") @APIResponse(responseCode = "200", description = "Product updated") @APIResponse(responseCode = "404", description = "Product ID not found") public Product updateProduct(@PathParam("id") Long id, @Valid Product updatedProduct) { Product entity = Product.findById(id); if (entity == null) { throw new NotFoundException("Product with ID " + id + " not found."); } entity.name = updatedProduct.name; entity.description = updatedProduct.description; entity.price = updatedProduct.price; entity.stockQuantity = updatedProduct.stockQuantity; entity.category = updatedProduct.category; return entity; } @DELETE @Path("/{id}") @Transactional @Operation(summary = "Delete a product by ID") @APIResponse(responseCode = "204", description = "Product deleted successfully") @APIResponse(responseCode = "404", description = "Product ID not found") public Response deleteProduct(@PathParam("id") Long id) { boolean deleted = Product.deleteById(id); if (!deleted) { throw new NotFoundException("Product with ID " + id + " not found."); } return Response.noContent().build(); } } 7. Reaktif REST Uç Noktaları vs Bloklayan Çalıştırma import io.smallrye.mutiny.Uni; import io.smallrye.mutiny.Multi; @GET @Path("/reactive/{id}") public Uni<Product> getProductReactive(@PathParam("id") Long id) { return Product.<Product>findByIdAsync(id) .onItem().ifNull().failWith(new NotFoundException("Product not found")); } @GET @Path("/stream") @Produces(MediaType.SERVER_SENT_EVENTS) public Multi<Product> streamProducts() { return Product.streamAll(); } 8. Genel İstisna Yönetimi ve Hata Standardı package com.ghaznix.api.exception; import jakarta.ws.rs.NotFoundException; import jakarta.ws.rs.core.MediaType; import jakarta.ws.rs.core.Response; import jakarta.ws.rs.ext.ExceptionMapper; import jakarta.ws.rs.ext.Provider; import java.time.Instant; import java.util.HashMap; import java.util.Map; @Provider public class GlobalExceptionMapper implements ExceptionMapper<Exception> { @Override public Response toResponse(Exception exception) { Map<String, Object> errorPayload = new HashMap<>(); errorPayload.put("timestamp", Instant.now().toString()); if (exception instanceof NotFoundException) { errorPayload.put("status", 404); errorPayload.put("error", "Not Found"); errorPayload.put("message", exception.getMessage()); return Response.status(Response.Status.NOT_FOUND) .entity(errorPayload) .type(MediaType.APPLICATION_JSON) .build(); } errorPayload.put("status", 500); errorPayload.put("error", "Internal Server Error"); errorPayload.put("message", exception.getMessage()); return Response.status(Response.Status.INTERNAL_SERVER_ERROR) .entity(errorPayload) .type(MediaType.APPLICATION_JSON) .build(); } } 9. @QuarkusTest ve REST Assured ile Otomatik Testler package com.ghaznix.api; import io.quarkus.test.junit.QuarkusTest; import io.restassured.http.ContentType; import org.junit.jupiter.api.Test; import static io.restassured.RestAssured.given; import static org.hamcrest.CoreMatchers.*; @QuarkusTest public class ProductResourceTest { @Test public void testGetAllProductsEndpoint() { given() .when().get("/api/products") .then() .statusCode(200) .contentType(ContentType.JSON); } @Test public void testCreateAndGetProduct() { Product product = new Product(); product.name = "Gaming Laptop"; product.description = "High-performance GPU laptop"; product.price = new java.math.BigDecimal("1499.99"); product.stockQuantity = 15; product.category = "Electronics"; // Test POST Endpoint Integer createdId = given() .contentType(ContentType.JSON) .body(product) .when().post("/api/products") .then() .statusCode(201) .body("name", equalTo("Gaming Laptop")) .extract().path("id"); // Test GET Endpoint by ID given() .pathParam("id", createdId) .when().get("/api/products/{id}") .then() .statusCode(200) .body("category", equalTo("Electronics")); } } ./mvnw test 10. GraalVM Yerli Yürütülebilir Dosyasına Derleme ./mvnw quarkus:dev ./mvnw package java -jar target/quarkus-app/quarkus-run.jar ./mvnw package -Dnative -Dquarkus.native.container-build=true ./target/quarkus-product-api-1.0.0-runner 2026-09-21 22:30:00,014 INFO [io.quarkus] (main) quarkus-product-api 1.0.0-runner native (powered by Quarkus 3.15.0) started in 0.018s. Listening on: http://0.0.0.0:8080 11. Performans Karşılaştırması: Quarkus vs Spring Boot Karşılaştırma Ölçütü Spring Boot (JVM) Quarkus (OpenJDK JVM) Quarkus (GraalVM Native) İyileşme Başlatma Süresi (Soğuk) 3,82 saniye 1,18 saniye 0,015 saniye 254 kat daha hızlı Bellek Kullanımı (RSS) 184 MB 108 MB 28 MB %84 bellek tasarrufu 12. Sonuç ve En İyi Uygulamalar Ghaznix Blog.
Java
Quarkus
REST API
Microservices
GraalVM
Reaktif Programlama
Hibernate Panache
Cloud Native
Yazılım Mimarisi