HTTP client for Java: overview of top libraries (Java 11, Apache, OkHttp, Retrofit)

HTTP client for Java: overview of top libraries

In modern Java development, almost no application can do without interaction via the HTTP protocol. Sending requests to REST APIs, downloading files, working with microservices — all of this requires a reliable and convenient HTTP client. In this article, we will look at four of the most popular libraries for working with HTTP in Java: the standard HttpClient (Java 11+), Apache HttpClient, OkHttp, and Retrofit. You will learn their features, strengths, and get practical code examples.

1. Java 11 HttpClient (java.net.http)

Starting with Java 11, a modern HTTP client was added to the standard library, designed to replace the outdated HttpURLConnection. It supports HTTP/2, WebSocket, asynchronous requests, and reactive streams.

Advantages:

• No additional dependencies required — built into the JDK.
• Support for HTTP/2 and automatic protocol upgrade.
• Convenient API with synchronous and asynchronous calls.
• Built-in support for cookie handling, redirects, and authentication.

Example of a synchronous GET request:

import java.net.URI;import java.net.http.HttpClient;import java.net.http.HttpRequest;import java.net.http.HttpResponse;

public class Java11HttpClientExample {    public static void main(String[] args) throws Exception {        HttpClient client = HttpClient.newHttpClient();        HttpRequest request = HttpRequest.newBuilder()                .uri(URI.create("https://jsonplaceholder.typicode.com/posts/1"))                .GET()                .build();

        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());        System.out.println("Status code: " + response.statusCode());        System.out.println("Body: " + response.body());    }}

Example of an asynchronous POST request:

import java.net.URI;import java.net.http.HttpClient;import java.net.http.HttpRequest;import java.net.http.HttpResponse;import java.net.http.HttpRequest.BodyPublishers;import java.util.concurrent.CompletableFuture;

public class AsyncPostExample {    public static void main(String[] args) {        HttpClient client = HttpClient.newHttpClient();        HttpRequest request = HttpRequest.newBuilder()                .uri(URI.create("https://jsonplaceholder.typicode.com/posts"))                .header("Content-Type", "application/json")                .POST(BodyPublishers.ofString("{\\"title\\":\\"foo\\",\\"body\\":\\"bar\\",\\"userId\\":1}"))                .build();

        CompletableFuture<HttpResponse<String>> future =                client.sendAsync(request, HttpResponse.BodyHandlers.ofString());        future.thenAccept(response -> {            System.out.println("Status: " + response.statusCode());            System.out.println("Body: " + response.body());        }).join();    }}

2. Apache HttpClient

A classic library from Apache, which for a long time was the de facto standard. The latest version (5.x) has received significant improvements: support for HTTP/2, improved connection pool handling, and more flexible configuration.

Advantages:

• Maximum flexibility and fine-tuning (timeouts, interceptors, caching).
• Proven stability over time.
• Support for various authentication schemes (Basic, Digest, NTLM).
• Good integration with proxies and SSL.

Example of a GET request with Apache HttpClient 5:

import org.apache.hc.client5.http.classic.methods.HttpGet;import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;import org.apache.hc.client5.http.impl.classic.Clos