Http Client in Mercury

Here’s an idiomatic Java example demonstrating an HTTP client, based on the concept shown in the Go example:

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

public class HttpClientExample {
    public static void main(String[] args) {
        try {
            // Create a URL object for the target website
            URL url = new URL("https://gobyexample.com");

            // Open a connection to the URL
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();

            // Set the request method to GET
            connection.setRequestMethod("GET");

            // Get the response code
            int responseCode = connection.getResponseCode();
            System.out.println("Response status: " + responseCode + " " + connection.getResponseMessage());

            // Read the response body
            BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String line;
            int lineCount = 0;
            while ((line = reader.readLine()) != null && lineCount < 5) {
                System.out.println(line);
                lineCount++;
            }

            // Close the reader and disconnect
            reader.close();
            connection.disconnect();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

This Java example demonstrates how to create a simple HTTP client using the java.net package. Here’s a breakdown of the code:

1. We import necessary classes from java.io and java.net packages.

2. In the main method, we wrap our code in a try-catch block to handle potential exceptions.

3. We create a URL object with the target website’s address.

4. We open a connection to the URL using url.openConnection() and cast it to HttpURLConnection.

5. We set the request method to GET using setRequestMethod("GET").

6. We get and print the response status code and message.

7. To read the response body, we create a BufferedReader that reads from the connection’s input stream.

8. We read and print the first 5 lines of the response body using a while loop.

9. Finally, we close the reader and disconnect the connection.

To run this program:

1. Save the code in a file named HttpClientExample.java.
2. Compile the code:

   javac HttpClientExample.java

3. Run the compiled program:

   java HttpClientExample

This example demonstrates how to make an HTTP GET request and process the response in Java. It uses the built-in HttpURLConnection class, which is suitable for simple HTTP requests. For more advanced HTTP client functionality, you might consider using libraries like Apache HttpClient or OkHttp.

Remember to handle exceptions appropriately in production code and consider factors like connection timeouts and proper resource management.