How can I use cURL in Java?

General Discussions
,
1

I need to make HTTP requests using curl java. Is cURL built into Java, or do I need to install it separately?

If it requires separate installation, how can I set it up and use it within my Java application?

2

If you’re looking for a native Java solution without installing anything, use :

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

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

        int responseCode = con.getResponseCode();
        System.out.println("Response Code: " + responseCode);

        BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
        String inputLine;
        StringBuilder response = new StringBuilder();
        
        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();

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

:white_check_mark: Why?

  • No external dependencies required.

  • Works with Java 8+.

  • Supports GET, POST, and headers.

3

For Java 11+, HttpClient is the preferred way to send HTTP requests:

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

public class CurlExample {
    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 Code: " + response.statusCode());
        System.out.println("Response: " + response.body());
    }
}

  • Modern API with better features.

  • Easier syntax than HttpURLConnection.

  • Works only in Java 11+.

4

For more flexibility (e.g., authentication, custom headers, JSON handling), use Apache HttpClient:

<!-- Add this to your Maven pom.xml -->
<dependencies>
    <dependency>
        <groupId>org.apache.httpcomponents.client5</groupId>
        <artifactId>httpclient5</artifactId>
        <version>5.2</version>
    </dependency>
</dependencies>


import org.apache.hc.client5.http.classic.methods.HttpGet;
import org.apache.hc.client5.http.classic.methods.CloseableHttpResponse;
import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.HttpClients;
import org.apache.hc.core5.http.io.entity.EntityUtils;

public class CurlExample {
    public static void main(String[] args) throws Exception {
        try (CloseableHttpClient client = HttpClients.createDefault()) {
            HttpGet request = new HttpGet("https://jsonplaceholder.typicode.com/posts/1");
            try (CloseableHttpResponse response = client.execute(request)) {
                System.out.println("Response Code: " + response.getCode());
                System.out.println("Response: " + EntityUtils.toString(response.getEntity()));
            }
        }
    }
}