HTTP client for Java: top libraries for working with HTTP requests

HTTP client for Java: top libraries for working with HTTP requests

Modern Java development is unthinkable without interaction with external services via HTTP. Whether it's a REST API, webhooks, or file uploads — a quality HTTP client is the foundation of any network application. In this article, we will break down the four best libraries for Java: from the classic Apache HttpClient to the modern Retrofit. You will learn their strengths, typical use cases, and see code examples.

1. Apache HttpClient (Apache HttpComponents)

This is perhaps the most well-known and mature library for HTTP in Java. It has been developed since 2004, supports HTTP/1.1 and HTTP/2, flexible connection pool configuration, proxies, authentication, and request interceptors. It is ideally suited for server-side applications with high customization requirements.

GET request example:

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.HttpClients;

try (CloseableHttpClient client = HttpClients.createDefault()) {    HttpGet request = new HttpGet("https://api.example.com/data");    String response = client.execute(request, classicHttpResponse -> {        return new String(classicHttpResponse.getEntity().getContent().readAllBytes());    });    System.out.println(response);}

Key features:

• Full support for HTTP/1.1 and HTTP/2
• Flexible management of connection pool and timeouts
• Built-in support for proxy servers and SSL/TLS
• Extensive ecosystem of plugins and interceptors
• Compatibility with Java 8+

2. OkHttp

A modern library from Square, optimized for Android and Java 8+. It stands out for its high performance due to asynchronous I/O and built-in HTTP/2 multiplexing. OkHttp automatically manages retries, caching, and data compression. It is often used in conjunction with Retrofit.

Asynchronous request:

import okhttp3.OkHttpClient;import okhttp3.Request;import okhttp3.Response;

OkHttpClient client = new OkHttpClient.Builder()        .connectTimeout(10, java.util.concurrent.TimeUnit.SECONDS)        .build();

Request request = new Request.Builder()        .url("https://api.example.com/data")        .build();

client.newCall(request).enqueue(new okhttp3.Callback() {    @Override    public void onFailure(okhttp3.Call call, IOException e) {        System.err.println("Error: " + e.getMessage());    }

    @Override    public void onResponse(okhttp3.Call call, Response response) throws IOException {        if (response.isSuccessful()) {            System.out.println(response.body().string());        }    }});

Advantages:

• Automatic support for HTTP/2 and SPDY
• Built-in caching and compression (gzip)
• Asynchronous calls without blocking threads
• Minimal JAR size (~600 KB)
• Integration with Android and Kotlin

3. Java 11 HttpClient (standard)

Starting with Java 11, a modern HTTP client was added to the standard JDK library. It supports HTTP/2, WebSocket, reactive data streams, and synchronous/asynchronous requests. It is an ideal solution for projects where you don't want to add third-party dependencies.

Synchronous GET with error handling:

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

HttpClient client = HttpClient.newHttpClient();HttpRequest request = HttpRequest.newBuilder()        .uri(URI.create("https://api.example.com/data"))        .GET()        .build();

try {    HttpResponse<St