REST API

Na engenharia de software corporativa moderna, a construção de APIs RESTful é a pedra angular do desenvolvimento de sistemas backend. Durante décadas, os desenvolvedores Java confiaram em frameworks tradicionais como Spring Boot ou Jakarta EE. Conheça o Quarkus—o framework Supersonic Subatomic Java projetado para OpenJDK HotSpot e GraalVM. 1. Por que escolher o Quarkus para APIs REST Java? A. O paradigma reativo RESTEasy B. Dev Services & Live Coding sem configuração 2. Arquitetura de API REST no Quarkus 3. Inicialização do projeto e dependências 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. Configurando propriedades da aplicação # 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. Modelo de domínio e Active Record com Panache 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. Construindo endpoints REST para produção 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. Endpoints REST reativos vs Execução bloqueante 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. Tratamento global de exceções e padrão de erro 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. Testes automatizados com @QuarkusTest & REST Assured 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. Empacotamento e compilação em executável nativo GraalVM ./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. Benchmarks de desempenho: Quarkus vs Spring Boot Métrica de Benchmark Spring Boot (JVM) Quarkus (OpenJDK JVM) Quarkus (GraalVM Native) Melhoria Tempo de inicialização (Frio) 3,82 segundos 1,18 segundos 0,015 segundos 254x mais rápido Uso de memória RSS 184 MB 108 MB 28 MB 84% de redução de memória 12. Conclusão e Melhores Práticas Ghaznix Blog.