How to Consume REST API in Quarkus

Hello everyone, today, we will learn how to consume REST API in Quarkus. Making HTTP requests is a core feature of programming, and is often one of the first things you want to do when learning new technology. For Java programmers, there are many ways to do it - core libraries in the JDK and third-party libraries.


Here, we will learn how to use the below technologies to consume REST API in Quarkus.
  • MP Rest Client 
  • JAX-RS Client 
  • ApacheHttpClient
  • Java 11 HttpClient 

Related topics,

Project Directory



Maven Dependencies[pom.xml]

<?xml version="1.0"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
https://maven.apache.org/xsd/maven-4.0.0.xsd" 
xmlns="http://maven.apache.org/POM/4.0.0" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <modelVersion>4.0.0</modelVersion>
    <groupId>org.knf.dev.demo</groupId>
    <artifactId>quarku-consume-restful-service</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <properties>
        <compiler-plugin.version>3.8.1</compiler-plugin.version>
        <failsafe.useModulePath>false</failsafe.useModulePath>
        <maven.compiler.release>17</maven.compiler.release>
        <project.build.sourceEncoding>UTF-8
        </project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8
        </project.reporting.outputEncoding>
        <quarkus.platform.artifact-id>quarkus-bom
        </quarkus.platform.artifact-id>
        <quarkus.platform.group-id>io.quarkus.platform
        </quarkus.platform.group-id>
        <quarkus.platform.version>2.7.3.Final
        </quarkus.platform.version>
        <surefire-plugin.version>3.0.0-M5
        </surefire-plugin.version>
    </properties>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>${quarkus.platform.group-id}</groupId>
                <artifactId>${quarkus.platform.artifact-id}
                </artifactId>
                <version>${quarkus.platform.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>io.quarkus</groupId>
            <artifactId>quarkus-rest-client</artifactId>
        </dependency>
        <dependency>
            <groupId>io.quarkus</groupId>
            <artifactId>quarkus-rest-client-jackson</artifactId>
        </dependency>
        <dependency>
            <groupId>io.quarkus</groupId>
            <artifactId>quarkus-apache-httpclient</artifactId>
        </dependency>
        <dependency>
            <groupId>io.quarkus</groupId>
            <artifactId>quarkus-arc</artifactId>
        </dependency>
        <dependency>
            <groupId>io.quarkus</groupId>
            <artifactId>quarkus-resteasy</artifactId>
        </dependency>
        <dependency>
            <groupId>io.quarkus</groupId>
            <artifactId>quarkus-junit5</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>io.rest-assured</groupId>
            <artifactId>rest-assured</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>${quarkus.platform.group-id}</groupId>
                <artifactId>quarkus-maven-plugin</artifactId>
                <version>${quarkus.platform.version}</version>
                <extensions>true</extensions>
                <executions>
                    <execution>
                        <goals>
                            <goal>build</goal>
                            <goal>generate-code</goal>
                            <goal>generate-code-tests</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>${compiler-plugin.version}</version>
                <configuration>
                    <compilerArgs>
                        <arg>-parameters</arg>
                    </compilerArgs>
                </configuration>
            </plugin>
            <plugin>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>${surefire-plugin.version}</version>
                <configuration>
                    <systemPropertyVariables>
                        <java.util.logging.manager>
                        org.jboss.logmanager.LogManager
                        </java.util.logging.manager>
                        <maven.home>${maven.home}</maven.home>
                    </systemPropertyVariables>
                </configuration>
            </plugin>
        </plugins>
    </build>
    <profiles>
        <profile>
            <id>native</id>
            <activation>
                <property>
                    <name>native</name>
                </property>
            </activation>
            <build>
                <plugins>
                    <plugin>
                   <artifactId>maven-failsafe-plugin</artifactId>
                    <version>${surefire-plugin.version}</version>
                        <executions>
                            <execution>
                                <goals>
                                    <goal>integration-test</goal>
                                    <goal>verify</goal>
                                </goals>
                                <configuration>
                                    <systemPropertyVariables>
                                        <native.image.path>
${project.build.directory}/${project.build.finalName}-runner
                                       </native.image.path>
                                        <java.util.logging.manager>
                                   org.jboss.logmanager.LogManager
                                        </java.util.logging.manager>
                                        <maven.home>${maven.home}
                                            </maven.home>
                                    </systemPropertyVariables>
                                </configuration>
                            </execution>
                        </executions>
                    </plugin>
                </plugins>
            </build>
            <properties>
                <quarkus.package.type>native</quarkus.package.type>
            </properties>
        </profile>
    </profiles>
</project>


Create a Post POJO

package org.knf.dev.demo.model;

public class Post {

    private String userId;
    private String id;
    private String body;
    private String title;

    public String getUserId() {
        return userId;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getBody() {
        return body;
    }

    public void setBody(String body) {
        this.body = body;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public Post() {
    }

    public Post(String userId,
                String id, String body, String title) {
        this.userId = userId;
        this.id = id;
        this.body = body;
        this.title = title;
    }
}


Method 1. How to use MicroProfile Rest Client to consume REST APIs.

Create PostService

package org.knf.dev.demo.mprestclientdemo;

import org.eclipse.microprofile.rest.client.inject.RegisterRestClient;
import org.knf.dev.demo.model.Post;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import java.util.List;

@Path("/posts")
/*
@RegisterRestClient allows Quarkus to know
that this interface is meant to be available for
CDI injection as a REST Client
 */
@RegisterRestClient
public interface PostService {

    @GET
    List<Post> fetchAllPosts();
}


Configure the base URL in application.properties

org.knf.dev.demo.mprestclientdemo.PostService/mp-rest/url = https://jsonplaceholder.typicode.com



Create PostResource

package org.knf.dev.demo.mprestclientdemo;

import org.eclipse.microprofile.rest.client.inject.RestClient;
import org.knf.dev.demo.model.Post;
import javax.inject.Inject;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import java.util.List;

@Path("/api/v1/mprestclient")
public class PostResource {

    @Inject
    @RestClient
    PostService postService;

    @GET
    @Path("/posts")
    public List<Post> fetchAllPosts() {
        return postService.fetchAllPosts();
    }
}



Method 2. How to use ApacheHttpClient to consume REST APIs

Create HttpService

package org.knf.dev.demo.apachehttpclient;

import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.knf.dev.demo.model.Post;
import javax.inject.Singleton;
import java.io.IOException;
import java.util.List;

@Singleton
public class HttpService {

    CloseableHttpClient httpClient = HttpClients.createDefault();

    public <T> List<T> fetchPosts(String url, Class<Post> responseType) 
            throws IOException {
        HttpGet request = new HttpGet(url);
        request.addHeader("content-type", "application/json");
        CloseableHttpResponse response = httpClient.execute(request);
        ObjectMapper objectMapper =
                new ObjectMapper();
        return objectMapper.
                readValue(response.getEntity().getContent(),
                        objectMapper.getTypeFactory().
               constructCollectionType(List.class, responseType));
    }
}


Create PostResource

package org.knf.dev.demo.apachehttpclient;

import org.knf.dev.demo.model.Post;
import javax.inject.Inject;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import java.io.IOException;
import java.util.List;

@Path("/api/v1/apachehttpclient")
public class PostResource {

    @Inject
    HttpService httpService;

    @GET
    @Path("/posts")
    public List<Post> fetchAllPosts() 
               throws IOException, InterruptedException {
        List<Post> posts = httpService.
                fetchPosts("https://jsonplaceholder.typicode.com/posts", 
                        Post.class);
        return posts;
    }
}




Method 3. How to use Java 11 HttpClient to consume REST APIs.

Create HttpService

package org.knf.dev.demo.newhttpclientdemo;

import com.fasterxml.jackson.databind.ObjectMapper;
import javax.inject.Singleton;
import java.io.IOException;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.util.List;

@Singleton
public class HttpService {

    private final HttpClient httpClient = HttpClient.
            newBuilder().version(HttpClient.Version.HTTP_2).build();

    public <T> List<T> fetchPosts(String url, Class<T> responseType)
            throws InterruptedException, IOException {
        HttpRequest request = HttpRequest.newBuilder().GET().
                uri(URI.create(url)).header("Accept",
                        "application/json").build();
        HttpResponse<String> response =
                httpClient.send(request, HttpResponse.
                        BodyHandlers.ofString());
        ObjectMapper objectMapper =
                new ObjectMapper();
        return objectMapper.
                readValue(response.body(),
                        objectMapper.getTypeFactory().
                 constructCollectionType(List.class, responseType));
    }
}


Create PostResource

package org.knf.dev.demo.newhttpclientdemo;

import java.io.IOException;
import java.util.List;
import javax.inject.Inject;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import org.knf.dev.demo.model.Post;

@Path("/api/v1/httpclient")
public class PostResource {

    @Inject
    HttpService httpService;

    @GET
    @Path("/posts")
    public List<Post> fetchAllPosts() 
              throws IOException, InterruptedException {

        HttpService httpService = new HttpService();
        List<Post> posts = httpService.
          fetchPosts("https://jsonplaceholder.typicode.com/posts", 
                Post.class);
        return posts;
    }
}



Method 4. How to use JAX-RS Client to consume REST APIs

Create PostResource

package org.knf.dev.demo.jaxrsclientdemo;

import org.knf.dev.demo.model.Post;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.core.GenericType;
import java.util.List;

@Path("/api/v1/jaxrsclient")
public class PostResource {

    private final Client client = 
                ClientBuilder.newBuilder().build();
    private final String url = 
               "https://jsonplaceholder.typicode.com/posts";

    @GET
    @Path("/posts")
    public List<Post> fetchAllPosts() {
        List<Post> posts = client.target(url).
                request().get(new GenericType<List<Post>>() {
        });
        return posts;
    }
}


Local Setup and Run the application

Download or clone the source code from GitHub to the local machine - Click here


Build application  jar file: mvn clean package

Start the application: java -jar quarkus-run.jar

Test Case 1: Use ApacheHttpClient to consume REST APIs.


Test Case 2: Use JAX-RS Client to consume REST APIs.


Test Case 3: Use MicroProfile Rest Client to consume REST APIs.


Test Case 4: Use Java 11 HttpClient to consume REST APIs.




More related topics,

Kotlin + Quarkus

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