import java.io.*;
import java.net.*;
import java.util.*;

public class URLReader {
    // do not instantiate this class
    private URLReader() {
    }

    public static InputStream getInputStream(String urlString, 
                                   Map<String, List<String>> inputHeaders, 
                                   Map<String, List<String>> outputHeaders,
                                   Map<String, String> formData)
                         throws MalformedURLException, IOException {
        URL url = new URL(urlString);
        URLConnection urlConn = url.openConnection();
        urlConn.setDoInput(true);
        urlConn.setUseCaches(false);

        if (inputHeaders != null) {
            for (String key: inputHeaders.keySet()) {
                List<String> values = inputHeaders.get(key);
                for (String value: values) {
                    urlConn.addRequestProperty(key, value);
                }
            }
        }

        if ((formData != null) && (!formData.isEmpty())) {
            urlConn.setDoOutput(true);
            urlConn.setRequestProperty("Content-Type", 
                                       "application/x-www-form-urlencoded");
            StringBuilder sb = new StringBuilder();
            for (String name: formData.keySet()) {
                sb.append(URLEncoder.encode(name, "UTF-8"))
                  .append("=")
                  .append(URLEncoder.encode(formData.get(name), "UTF-8"))
                  .append("&");
            }

            DataOutputStream out = new DataOutputStream(urlConn.getOutputStream());
            out.writeBytes(sb.substring(0, sb.length() - 1));
            out.flush();
            out.close();
        }
        else {
            urlConn.setDoOutput(false);
        }

        if (outputHeaders != null) {
            outputHeaders.clear();
            outputHeaders.putAll(urlConn.getHeaderFields());
        }

        return urlConn.getInputStream();
    }

    // Simple GET requests
    public static InputStream getInputStream(String urlString) 
                         throws MalformedURLException , IOException {
        return getInputStream(urlString, null, null, null);
    }

    // Simple POST. We don't care about headers.
    public static InputStream getInputStream(String urlString,
                                   Map<String, String> formData) 
                         throws MalformedURLException, IOException {
        return getInputStream(urlString, null, null, formData);
    }
}

import java.io.*;
import java.util.*;

public class TestURLReader {
    public static void main(String[] args) throws Exception {
        Map<String, List<String>> sendHeaders = new HashMap<String, List<String>>();
        sendHeaders.put("Cookie", Arrays.asList("JSESSIONID=c0a89f8022bafe6e82e9c1a340a691a18402682d39ac"));
        Map<String, List<String>> respHeaders = new HashMap<String, List<String>>();

        BufferedReader reader = new BufferedReader(
                                    new InputStreamReader(
                                    URLReader.getInputStream("http://localhost:8080/welcome.do", 
                                                            sendHeaders, 
                                                            respHeaders, 
                                                            null)
                                    ));

        // print response headers
        for (String k: respHeaders.keySet()) {
            List<String> values = respHeaders.get(k);
            for (String v: values) {
                System.out.printf("%s: %s\n", k, v);
            }
        }

        // print contents of the page
        String line = reader.readLine();
        while (line != null) {
            System.out.println(line);
            line = reader.readLine();
        }

        reader.close();
    }
}