Read Web Pages with Nonblocking SocketChannel in Java

//from w w w.  j a  v a 2 s .c om
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;
import java.util.Iterator;
import java.util.Set;

public class Main {
  static Selector selector;

  public static void main(String args[]) throws Exception {
    int slashPos;

    String resource = "www.java2s.com/index.htm"; // skip HTTP://
    slashPos = resource.indexOf('/'); // find host/file separator
    if (slashPos < 0) {
      resource = resource + "/";
      slashPos = resource.indexOf('/');
    }
    String file = resource.substring(slashPos); // isolate host and file parts
    String host = resource.substring(0, slashPos);
    System.out.println("Host to contact: '" + host + "'");
    System.out.println("File to fetch : '" + file + "'");

    
    Charset charset = Charset.forName("ISO-8859-1");
    CharsetDecoder decoder = charset.newDecoder();
    CharsetEncoder encoder = charset.newEncoder();

    ByteBuffer buffer = ByteBuffer.allocateDirect(1024);
    CharBuffer charBuffer = CharBuffer.allocate(1024);

    InetSocketAddress socketAddress = new InetSocketAddress(host, 80);
    SocketChannel channel = SocketChannel.open();
    channel.configureBlocking(false);
    channel.connect(socketAddress);

    selector = Selector.open();

    channel.register(selector, SelectionKey.OP_CONNECT | SelectionKey.OP_READ);

    while (selector.select(500) > 0) {
      Set readyKeys = selector.selectedKeys();
      Iterator readyItor = readyKeys.iterator();

      while (readyItor.hasNext()) {

        SelectionKey key = (SelectionKey) readyItor.next();
        readyItor.remove();
        SocketChannel keyChannel = (SocketChannel) key.channel();

        if (key.isConnectable()) {
          if (keyChannel.isConnectionPending()) {
            keyChannel.finishConnect();
          }
          String request = "GET " + file + " \r\n\r\n";
          keyChannel.write(encoder.encode(CharBuffer.wrap(request)));
        } else if (key.isReadable()) {
          keyChannel.read(buffer);
          buffer.flip();

          decoder.decode(buffer, charBuffer, false);
          charBuffer.flip();
          System.out.print(charBuffer);

          buffer.clear();
          charBuffer.clear();

        } else {
          System.err.println("Unknown key");
        }
      }
    }
    channel.close();
    System.out.println("\nDone.");
  }
}