HTTP Requests in Java: A Complete Guide with Examples

Introduction

In modern applications, communicating with web servers and APIs is a common requirement. Whether you are building a REST API client, fetching data from a server, or sending POST requests, Java provides multiple ways to handle HTTP requests.

In this guide, we will cover the basics of making HTTP requests in Java, explore different approaches, and provide real-world GET and POST examples.

Ways to Make HTTP Requests in Java

Java provides multiple options for sending HTTP requests:

1. HttpURLConnection (Core Java) – Simple, built-in way to handle HTTP requests.

2. HttpClient (Java 11+) – Modern, efficient, and feature-rich API.

3. Third-party libraries (OkHttp, Apache HttpClient) – Widely used in enterprise-level applications.

Example 1: Using HttpURLConnection (GET Request)

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class GetRequestExample {
    public static void main(String[] args) throws Exception {
        URL url = new URL("https://jsonplaceholder.typicode.com/posts/1");
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setRequestMethod("GET");

        BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String inputLine;
        StringBuilder response = new StringBuilder();

        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();

        System.out.println("Response: " + response.toString());
    }
}

✅ Output: JSON response from API.

Example 2: Using HttpURLConnection (POST Request)

import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class PostRequestExample {
    public static void main(String[] args) throws Exception {
        URL url = new URL("https://jsonplaceholder.typicode.com/posts");
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setRequestMethod("POST");
        conn.setRequestProperty("Content-Type", "application/json; utf-8");
        conn.setDoOutput(true);

        String jsonInput = "{\"title\":\"Java HTTP Request\",\"body\":\"Learning POST request in Java\",\"userId\":1}";

        try (OutputStream os = conn.getOutputStream()) {
            byte[] input = jsonInput.getBytes("utf-8");
            os.write(input, 0, input.length);
        }

        System.out.println("Response Code: " + conn.getResponseCode());
    }
}

✅ Output: 201 Created response with new resource ID.

Example 3: Using HttpClient (Java 11+)

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

public class HttpClientExample {
    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("Response: " + response.body());
    }
}

✅ Output: JSON response from API.

Comparison: HttpURLConnection vs HttpClient

Real-World Applications

• Consuming REST APIs

• Fetching data from web services

• Sending JSON/XML payloads

• Integrating with payment gateways, authentication APIs

• Building microservices communication

Best Practices

✔ Use HttpClient (Java 11+) for modern projects.
✔ Set appropriate headers (Content-Type, Authorization).
✔ Handle timeouts and exceptions.
✔ Prefer third-party libraries (OkHttp, Apache HttpClient) for large-scale apps.

Conclusion

Java offers multiple ways to perform HTTP requests, from the traditional HttpURLConnection to the modern HttpClient. By mastering these, developers can easily connect to REST APIs, web services, and cloud-based applications.

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