Java HttpClient — GET and POST Requests

import java.net.URI;
import java.net.http.*;
import java.net.http.HttpResponse.BodyHandlers;
import java.time.Duration;

public class HttpClientDemo {
    private static final HttpClient client = HttpClient.newBuilder()
        .connectTimeout(Duration.ofSeconds(10))
        .followRedirects(HttpClient.Redirect.NORMAL)
        .build();

    // GET request
    public static String get(String url) throws Exception {
        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create(url))
            .header("Accept", "application/json")
            .GET()
            .build();

        HttpResponse<String> response = client.send(request, BodyHandlers.ofString());

        if (response.statusCode() != 200) {
            throw new RuntimeException("HTTP " + response.statusCode());
        }
        return response.body();
    }

    // POST JSON
    public static String postJson(String url, String json) throws Exception {
        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create(url))
            .header("Content-Type", "application/json")
            .POST(HttpRequest.BodyPublishers.ofString(json))
            .build();

        HttpResponse<String> response = client.send(request, BodyHandlers.ofString());
        return response.body();
    }

    // Async GET
    public static void asyncGet(String url) {
        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create(url))
            .build();

        client.sendAsync(request, BodyHandlers.ofString())
            .thenApply(HttpResponse::body)
            .thenAccept(System.out::println)
            .join();
    }

    public static void main(String[] args) throws Exception {
        String data = get("https://api.example.com/users");
        System.out.println(data);

        String result = postJson("https://api.example.com/users",
            "{\"name\": \"Alice\", \"email\": \"alice@test.com\"}");
        System.out.println(result);
    }
}