Java Simple HTTP GET

Use Java URLConnection to get HTTP request.

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.Base64;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class HttpGet {
    public static void main(String[] args) throws Exception {
        boolean verbose = false;
        String basic = null;
        List<String> urls = new ArrayList<>();
        Map<String, String> headers = new HashMap<>();
        for (int i = 0; i < args.length; ++i) {
            if ("-h".equals(args[i]) || "--header".equals(args[i])) {
                if (i + 1 < args.length) {
                    String[] parts = args[i + 1].split("=", 2);
                    if (parts.length == 2) {
                        headers.put(parts[0], parts[1]);
                    } else {
                        System.err.println("Ignore invalid header: " + args[i + 1]);
                    }
                    i++;
                } else {
                    System.err.println("Ignore invalid option: " + args[i]);
                }
            } else if ("-u".equals(args[i]) || "--user".equals(args[i])) {
                if (i + 1 < args.length) {
                    basic = args[++i];
                } else {
                    System.err.println("Ignore invalid option: " + args[i]);
                }
            } else if ("-v".equals(args[i]) || "--verbose".equals(args[i])) {
                verbose = true;
            } else {
                urls.add(args[i]);
            }
        }

        if (urls.isEmpty()) {
            System.err.println("Usage: java " + HttpGet.class.getName() + " [-h name=value] [-u username:password] [-v] <URL>");
            System.exit(1);
        }

        URL url = new URL(urls.get(0));
        HttpURLConnection httpUrlConnection = (HttpURLConnection) url.openConnection();

        for (Map.Entry<String, String> entry : headers.entrySet()) {
            httpUrlConnection.setRequestProperty(entry.getKey(), entry.getValue());
        }

        if (basic != null) {
            httpUrlConnection.setRequestProperty("Authorization", "Basic " + Base64.getEncoder().encodeToString(basic.getBytes()));
        }

        httpUrlConnection.connect();

        if (verbose) {
            System.out.println(httpUrlConnection.getHeaderField(null));
            for (Map.Entry<String, List<String>> entry : httpUrlConnection.getHeaderFields().entrySet()) {
                String key = entry.getKey();
                String value = entry.getValue().get(0);
                if (key != null) {
                    System.out.println(key + ": " + value);
                }
            }
            System.out.println();
        }

        try (InputStream is = httpUrlConnection.getInputStream();
             InputStreamReader isReader = new InputStreamReader(is);
             BufferedReader reader = new BufferedReader(isReader)) {
            StringBuilder sb = new StringBuilder();
            String line;
            while ((line = reader.readLine()) != null) {
                sb.append(line).append('\n');
            }
            System.out.println(sb.toString());
        } catch (Exception e) {
            System.err.println(e.getMessage());
        }
    }
}