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 class:

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;
}
}


Run the Quarkus Application

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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