Nbs.java

//non blocking socket server

package server3;

/**
 *
 * 
 */
import java.io.*;
import java.nio.*;
import java.nio.channels.*;
import java.nio.channels.spi.*;
import java.nio.charset.*;
import java.net.*;
import java.util.*;
//import javax.script.*;
public class Nbs {

    static void handle_message(SocketChannel client, String message) throws Exception {
        
        if (message.startsWith("GET / HTTP")) {
            write(client, "HTTP/1.1 200 OK\r\nContent-Type: text/html; charset=utf-8\r\n\r\nThis is the resῼponse yall");
            client.close();
          /*  ScriptEngineManager mgr = new ScriptEngineManager();
          ScriptEngine jsEngine = mgr.getEngineByName("JavaScript");
          try {
            jsEngine.eval("print('Hello, world!')");
          } catch (ScriptException ex) {
              ex.printStackTrace();
          }*/

          
        }

    }
    static void write(SocketChannel client, String message) throws Exception{
        byte[] message_bytes = message.getBytes("UTF8");
        ByteBuffer b = ByteBuffer.allocate(message_bytes.length);
        byte[] arr = b.array();

        for (int i = 0; i < arr.length; i++) {
            arr[i] = message_bytes[i];
        }
        System.out.println(message + "--");
        client.write(b);
    }
    static String read(SocketChannel client) throws Exception {
          
       ByteBuffer b = ByteBuffer.allocate(1024);
       try {
        client.read(b);
       } catch (Exception e) {
        //System.out.println("oops");
            client.close();
           return "yo";
       //return "";
       }
       b.flip();
       String ret = new String(b.array(), "UTF8");
       System.out.println(":)");
       return ret;
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws IOException, Exception {
        // TODO code application logic here
        Selector acceptSelector = Selector.open();
        //Selector acceptSelector = SelectorProvider.provider().openSelector();
        ServerSocketChannel ssc = ServerSocketChannel.open();
        ssc.configureBlocking(false);
        //InetAddress lh = InetAddress.getLocalHost();
	String lh = "localhost";
        int port = 80;
        InetSocketAddress isa = new InetSocketAddress(lh, port);
	ssc.socket().bind(isa);
        
        SelectionKey acceptKey = ssc.register(acceptSelector, SelectionKey.OP_ACCEPT);
        int keysAdded = 0;

        while ((keysAdded = acceptSelector.select()) > 0) {
            Set readyKeys = acceptSelector.selectedKeys();
	    Iterator i = readyKeys.iterator();
	    // Walk through the ready keys collection and process date requests.
	    while (i.hasNext()) {
		SelectionKey sk = (SelectionKey)i.next();
                i.remove();

                if (sk.isAcceptable()) {
                    ServerSocketChannel nextReady = (ServerSocketChannel)sk.channel();
                    // Accept the date request and send back the date string
                    SocketChannel client = nextReady.accept();
                    //Socket s = channel.socket();
                    client.configureBlocking( false );
                    client.register( acceptSelector, SelectionKey.OP_READ|SelectionKey.OP_WRITE  );
                    
                }
                else if (sk.isReadable()) {
                    SocketChannel client = (SocketChannel) sk.channel();
                    //Socket s = client.socket();
                    //System.out.println(read(s.getInputStream())); //no can do here
                    String message = read(client);
                    handle_message(client, message);
                }
               
                    if (sk.isValid() && sk.isWritable()) {
                        //SocketChannel client = (SocketChannel) sk.channel();
                    }
                
            }
        }
    }
}