MainClass.java Source code

Introduction

Here is the source code for MainClass.java

Source

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
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 MainClass {
    public static void main(String[] args) throws IOException {
        Charset charset = Charset.forName("ISO-8859-1");
        CharsetEncoder encoder = charset.newEncoder();
        CharsetDecoder decoder = charset.newDecoder();

        ByteBuffer buffer = ByteBuffer.allocate(512);

        Selector selector = Selector.open();

        ServerSocketChannel server = ServerSocketChannel.open();
        server.socket().bind(new java.net.InetSocketAddress(8000));
        server.configureBlocking(false);
        SelectionKey serverkey = server.register(selector, SelectionKey.OP_ACCEPT);

        for (;;) {
            selector.select();
            Set keys = selector.selectedKeys();

            for (Iterator i = keys.iterator(); i.hasNext();) {
                SelectionKey key = (SelectionKey) i.next();
                i.remove();

                if (key == serverkey) {
                    if (key.isAcceptable()) {
                        SocketChannel client = server.accept();
                        client.configureBlocking(false);
                        SelectionKey clientkey = client.register(selector, SelectionKey.OP_READ);
                        clientkey.attach(new Integer(0));
                    }
                } else {
                    SocketChannel client = (SocketChannel) key.channel();
                    if (!key.isReadable())
                        continue;
                    int bytesread = client.read(buffer);
                    if (bytesread == -1) {
                        key.cancel();
                        client.close();
                        continue;
                    }
                    buffer.flip();
                    String request = decoder.decode(buffer).toString();
                    buffer.clear();
                    if (request.trim().equals("quit")) {
                        client.write(encoder.encode(CharBuffer.wrap("Bye.")));
                        key.cancel();
                        client.close();
                    } else {
                        int num = ((Integer) key.attachment()).intValue();
                        String response = num + ": " + request.toUpperCase();
                        client.write(encoder.encode(CharBuffer.wrap(response)));
                        key.attach(new Integer(num + 1));
                    }
                }
            }
        }
    }
}