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

// Program connects to Web server and downloads the specified URL
// Thanks to:
//     Java Examples in a Nutshell by David Flanagan pp.189-191
public class ClientHttp {
  public static void main(String[] args) {
    try {
       if ((args.length != 1) && (args.length != 2)) throw new IllegalArgumentException("Wrong number of arguments");
       
       OutputStream to_stream;
       if (args.length == 2) {
         to_stream = new FileOutputStream(args[1]);
       } else {
         to_stream = System.out;
       }
              
       URL oururl = new URL(args[0]);  // User-specified URL
       String ourprotocol = oururl.getProtocol();
       if (!ourprotocol.equals("http"))  throw new IllegalArgumentException("URL must use the 'http:' protocol");

	   String ourhost = oururl.getHost();
	   int ourport = oururl.getPort();
	   if (ourport == -1) ourport = 80;
	   
	   String ourfilename = oururl.getFile();
	   
	   Socket oursocket = new Socket(ourhost, ourport);
	   
	   InputStream from_ourserver = oursocket.getInputStream();
	   PrintWriter to_ourserver = new PrintWriter(new OutputStreamWriter(oursocket.getOutputStream()));
	   
	   to_ourserver.println("GET " + ourfilename);
	   to_ourserver.flush();
	   
	   byte[] ourbuffer = new byte[4096];
	   int ourbytes_read;
	   while ((ourbytes_read = from_ourserver.read(ourbuffer)) != -1) to_stream.write(ourbuffer, 0, ourbytes_read);
	   
	   oursocket.close();
	   to_stream.close();
	   
       
    } catch (Exception err) {  // Errors
       System.err.println(err);
       System.err.println("Usage: java ClientHttp <URL> [<filename>]");
    }
  }
}