By Version

Edit this Page

Quarkus Extension for Spring Web API

While users are encouraged to use Jakarta REST (formerly known as JAX-RS) annotations for defining REST endpoints, Quarkus provides a compatibility layer for Spring Web in the form of the spring-web extension.

This guide explains how a Quarkus application can leverage the well known Spring Web annotations to define RESTful services.

Prerequisites

To complete this guide, you need:

Roughly 15 minutes
An IDE
JDK 17+ installed with JAVA_HOME configured appropriately
Apache Maven 3.9.9
Optionally the Quarkus CLI if you want to use it
Optionally Mandrel or GraalVM installed and configured appropriately if you want to build a native executable (or Docker if you use a native container build)

Solution

We recommend that you follow the instructions in the next sections and create the application step by step. However, you can go right to the completed example.

Clone the Git repository: git clone https://github.com/quarkusio/quarkus-quickstarts.git, or download an archive.

The solution is located in the spring-web-quickstart directory.

Creating the Maven project

First, we need a new project. Create a new project with the following command:

CLI

quarkus create app org.acme:spring-web-quickstart \
    --extension='spring-web,rest-jackson' \
    --no-code
cd spring-web-quickstart

To create a Gradle project, add the --gradle or --gradle-kotlin-dsl option.

For more information about how to install and use the Quarkus CLI, see the Quarkus CLI guide.

Maven

mvn io.quarkus.platform:quarkus-maven-plugin:3.16.4:create \
    -DprojectGroupId=org.acme \
    -DprojectArtifactId=spring-web-quickstart \
    -Dextensions='spring-web,rest-jackson' \
    -DnoCode
cd spring-web-quickstart

To create a Gradle project, add the -DbuildTool=gradle or -DbuildTool=gradle-kotlin-dsl option.

For Windows users:

If using cmd, (don’t use backward slash \ and put everything on the same line)
If using Powershell, wrap -D parameters in double quotes e.g. "-DprojectArtifactId=spring-web-quickstart"

This command generates a project which imports the spring-web extension.

If you already have your Quarkus project configured, you can add the spring-web extension to your project by running the following command in your project base directory:

CLI

quarkus extension add spring-web,rest-jackson

Maven

./mvnw quarkus:add-extension -Dextensions='spring-web,rest-jackson'

Gradle

./gradlew addExtension --extensions='spring-web,rest-jackson'

This will add the following to your build file:

pom.xml

<dependency>
    <groupId>io.quarkus</groupId>
    <artifactId>quarkus-spring-web</artifactId>
</dependency>
<dependency>
    <groupId>io.quarkus</groupId>
    <artifactId>quarkus-rest-jackson</artifactId>
</dependency>

build.gradle

implementation("io.quarkus:quarkus-spring-web")
implementation("io.quarkus:quarkus-rest-jackson")

quarkus-spring-web needs to be complemented with either quarkus-rest-jackson or quarkus-resteasy-jackson in order to work.

GreetingController

Create the src/main/java/org/acme/spring/web/GreetingController.java file, a controller with the Spring Web annotations to define our REST endpoint, as follows:

package org.acme.spring.web;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/greeting")
public class GreetingController {

    @GetMapping
    public String hello() {
        return "hello";
    }
}

GreetingControllerTest

Note that a test for the controller has been created as well:

package org.acme.spring.web;

import io.quarkus.test.junit.QuarkusTest;
import org.junit.jupiter.api.Test;

import static io.restassured.RestAssured.given;
import static org.hamcrest.CoreMatchers.is;

@QuarkusTest
public class GreetingControllerTest {

    @Test
    public void testHelloEndpoint() {
        given()
          .when().get("/greeting")
          .then()
             .statusCode(200)
             .body(is("hello"));
    }

}

Package and run the application

Run the application with:

CLI

quarkus dev

Maven

./mvnw quarkus:dev

Gradle

./gradlew --console=plain quarkusDev

Open your browser to http://localhost:8080/greeting.

The result should be: {"message": "hello"}.

Run the application as a native executable

You can generate the native executable with:

CLI

quarkus build --native

Maven

./mvnw install -Dnative

Gradle

./gradlew build -Dquarkus.native.enabled=true

Going further with an endpoint returning JSON

The GreetingController above was an example of a very simple endpoint. In many cases however it is required to return JSON content. The following example illustrates how that could be achieved using a Spring RestController:

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/greeting")
public class GreetingController {

    @GetMapping("/{name}")
    public Greeting hello(@PathVariable(name = "name") String name) {
        return new Greeting("hello " + name);
    }

    public static class Greeting {
        private final String message;

        public Greeting(String message) {
            this.message = message;
        }

        public String getMessage(){
            return message;
        }
    }
}

The corresponding test could look like:

package org.acme.spring.web;

import io.quarkus.test.junit.QuarkusTest;
import org.junit.jupiter.api.Test;

import static io.restassured.RestAssured.given;
import static org.hamcrest.CoreMatchers.is;

@QuarkusTest
public class GreetingControllerTest {

    @Test
    public void testHelloEndpoint() {
        given()
          .when().get("/greeting/quarkus")
          .then()
            .statusCode(200)
            .body("message", is("hello quarkus"));
    }

}

It should be noted that when using the Spring Web support in Quarkus, Jackson is automatically added to the classpath and properly set up.

Adding OpenAPI and Swagger-UI

You can add support for OpenAPI and Swagger-UI by using the quarkus-smallrye-openapi extension.

Add the extension by running this command:

./mvnw quarkus:add-extension -Dextensions="io.quarkus:quarkus-smallrye-openapi"

This will add the following to your pom.xml:

<dependency>
    <groupId>io.quarkus</groupId>
    <artifactId>quarkus-smallrye-openapi</artifactId>
</dependency>

This is enough to generate a basic OpenAPI schema document from your REST Endpoints:

curl http://localhost:8080/q/openapi

You will see the generated OpenAPI schema document:

---
openapi: 3.0.1
info:
  title: Generated API
  version: "1.0"
paths:
  /greeting:
    get:
      responses:
        "200":
          description: OK
          content:
            '*/*':
              schema:
                type: string
  /greeting/{name}:
    get:
      parameters:
      - name: name
        in: path
        required: true
        schema:
          type: string
      responses:
        "200":
          description: OK
          content:
            'application/json':
              schema:
                $ref: '#/components/schemas/Greeting'
components:
  schemas:
    Greeting:
      type: object
      properties:
        message:
          type: string

Also see the OpenAPI Guide

Adding MicroProfile OpenAPI Annotations

You can use MicroProfile OpenAPI to better document your schema, example, adding the following to the class level of the GreetingController:

@OpenAPIDefinition(
    info = @Info(
        title="Greeting API",
        version = "1.0.1",
        contact = @Contact(
            name = "Greeting API Support",
            url = "http://exampleurl.com/contact",
            email = "techsupport@example.com"),
        license = @License(
            name = "Apache 2.0",
            url = "https://www.apache.org/licenses/LICENSE-2.0.html"))
)

And describe your endpoints like this:

@Tag(name = "Hello", description = "Just say hello")
@GetMapping(produces=MediaType.TEXT_PLAIN_VALUE)
public String hello() {
    return "hello";
}

@GetMapping(value = "/{name}", produces=MediaType.APPLICATION_JSON_VALUE)
@Tag(name = "Hello to someone", description = "Just say hello to someone")
public Greeting hello(@PathVariable(name = "name") String name) {
    return new Greeting("hello " + name);
}

will generate this OpenAPI schema:

---
openapi: 3.0.1
info:
  title: Greeting API
  contact:
    name: Greeting API Support
    url: http://exampleurl.com/contact
    email: techsupport@example.com
  license:
    name: Apache 2.0
    url: https://www.apache.org/licenses/LICENSE-2.0.html
  version: 1.0.1
tags:
- name: Hello
  description: Just say hello
- name: Hello to someone
  description: Just say hello to someone
paths:
  /greeting:
    get:
      tags:
      - Hello
      responses:
        "200":
          description: OK
          content:
            '*/*':
              schema:
                type: string
  /greeting/{name}:
    get:
      tags:
      - Hello to someone
      parameters:
      - name: name
        in: path
        required: true
        schema:
          type: string
      responses:
        "200":
          description: OK
          content:
            '*/*':
              schema:
                $ref: '#/components/schemas/Greeting'
components:
  schemas:
    Greeting:
      type: object
      properties:
        message:
          type: string

Using Swagger UI

Swagger UI is included by default when running in Dev or Test mode, and can optionally be added to Prod mode. See the Swagger UI Guide for more details.

Navigate to localhost:8080/q/swagger-ui/ and you will see the Swagger UI screen:

Swagger UI

Supported Spring Web functionalities

Quarkus currently supports a subset of the functionalities that Spring Web provides. More specifically Quarkus supports the REST related features of Spring Web (think of @RestController instead of @Controller).

Annotations

The table below summarizes the supported annotations:

Table 1. Supported Spring Web annotation
Name	Comments
@RestController
@RequestMapping
@GetMapping
@PostMapping
@PutMapping
@DeleteMapping
@PatchMapping
@RequestParam
@RequestHeader
@MatrixVariable
@PathVariable
@CookieValue
@RequestBody
@ResponseStatus
@ExceptionHandler	Can only be used in a @RestControllerAdvice class, not on a per-controller basis
@RestControllerAdvice	Only the @ExceptionHandler capability is supported

Controller method return types

The following method return types are supported:

Primitive types
String (which will be used as a literal, no Spring MVC view support is provided)
POJO classes which will be serialized via JSON
org.springframework.http.ResponseEntity

Controller method parameter types

In addition to the method parameters that can be annotated with the appropriate Spring Web annotations from the previous table, jakarta.servlet.http.HttpServletRequest and jakarta.servlet.http.HttpServletResponse are also supported. For this to function however, users need to add the quarkus-undertow dependency.

Exception handler method return types

The following method return types are supported:

org.springframework.http.ResponseEntity
java.util.Map

Other return types mentioned in the Spring ExceptionHandler javadoc are not supported.

Exception handler method parameter types

The following parameter types are supported, in arbitrary order:

An exception argument: declared as a general Exception or as a more specific exception. This also serves as a mapping hint if the annotation itself does not narrow the exception types through its value().
Request and/or response objects (typically from the Servlet API). You may choose any specific request/response type, e.g. ServletRequest / HttpServletRequest. To use Servlet API, the quarkus-undertow dependency needs to be added.

Other parameter types mentioned in the Spring ExceptionHandler javadoc are not supported.

Important Technical Note

Please note that the Spring support in Quarkus does not start a Spring Application Context nor are any Spring infrastructure classes run. Spring classes and annotations are only used for reading metadata and / or are used as user code method return types or parameter types. What that means for end users, is that adding arbitrary Spring libraries will not have any effect. Moreover, Spring infrastructure classes (like org.springframework.beans.factory.config.BeanPostProcessor for example) will not be executed.

Conversion Table

The following table shows how Spring Web annotations can be converted to Jakarta REST annotations.

Spring Jakarta REST Comments

Spring	Jakarta REST	Comments
@RestController		There is no equivalent in Jakarta REST. Annotating a class with @Path suffices
@RequestMapping(path="/api")	@Path("/api")
@RequestMapping(consumes="application/json")	@Consumes("application/json")
@RequestMapping(produces="application/json")	@Produces("application/json")
@RequestParam	@QueryParam
@PathVariable	@PathParam
@RequestBody		No equivalent in Jakarta REST. Method parameters corresponding to the body of the request are handled in Jakarta REST without requiring any annotation
@RestControllerAdvice		No equivalent in Jakarta REST
@ResponseStatus		No equivalent in Jakarta REST
@ExceptionHandler		No equivalent annotation in Jakarta REST. Exceptions are handled by implementing `jakarta.ws.rs.ext.ExceptionMapper`

@RestController

There is no equivalent in Jakarta REST. Annotating a class with @Path suffices

@RequestMapping(path="/api")

@Path("/api")

@RequestMapping(consumes="application/json")

@Consumes("application/json")

@RequestMapping(produces="application/json")

@Produces("application/json")

@RequestParam

@QueryParam

@PathVariable

@PathParam

@RequestBody

No equivalent in Jakarta REST. Method parameters corresponding to the body of the request are handled in Jakarta REST without requiring any annotation

@RestControllerAdvice

No equivalent in Jakarta REST

@ResponseStatus

No equivalent in Jakarta REST

@ExceptionHandler

No equivalent annotation in Jakarta REST. Exceptions are handled by implementing jakarta.ws.rs.ext.ExceptionMapper

More Spring guides

Quarkus has more Spring compatibility features. See the following guides for more details:

Quarkus Extension for Spring Web API

Prerequisites

Solution

Creating the Maven project

GreetingController

GreetingControllerTest

Package and run the application

Run the application as a native executable

Going further with an endpoint returning JSON

Adding OpenAPI and Swagger-UI

Adding MicroProfile OpenAPI Annotations

Using Swagger UI

Supported Spring Web functionalities

Annotations

Controller method return types

Controller method parameter types

Exception handler method return types

Exception handler method parameter types

Important Technical Note

Conversion Table

More Spring guides

Related content

On the same topics