Как написать приложение клиент - сервер на Java

package ru.nwleague.network;
 
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
 
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
 
/**
 * Location: network
 * Created: IceSqueez
 * Date: 22.12.2013
 * Time: 23:25
 */
 
public class Client implements Runnable {
    private final String host;
    private final int port;
 
    public Client(String host, int port) {
        this.host = host;
        this.port = port;
    }
 
    @Override
    public void run() {
        EventLoopGroup eventLoopGroup = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap()
                    .group(eventLoopGroup)
                    .channel(NioSocketChannel.class)
                    .handler(new ClientInitializer());
            Channel channel = bootstrap.connect(host, port).sync().channel();
            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
            while(true) {
                channel.write(reader.readLine() + "\r\n");
            }
        } catch (InterruptedException | IOException ignored) {
        } finally {
            eventLoopGroup.shutdownGracefully();
        }
    }
}

package ru.nwleague.network;
 
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundMessageHandlerAdapter;
 
/**
 * Location: network
 * Created: IceSqueez
 * Date: 22.12.2013
 * Time: 23:26
 */
 
public class ClientHandler extends ChannelInboundMessageHandlerAdapter<String> {
 
    @Override
    public void messageReceived(ChannelHandlerContext channelHandlerContext, String message) throws Exception {
        System.out.println(message);
    }
}

package ru.nwleague.network;
 
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
 
/**
 * Location: network
 * Created: IceSqueez
 * Date: 22.12.2013
 * Time: 23:25
 */
 
public class ClientInitializer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel channel) throws Exception {
        ChannelPipeline pipeline = channel.pipeline();
        pipeline.addLast("framer", new DelimiterBasedFrameDecoder(2556, Delimiters.lineDelimiter()));
        pipeline.addLast("decoder", new StringDecoder());
        pipeline.addLast("encoder", new StringEncoder());
        pipeline.addLast("handler", new ClientHandler());
    }
}

package ru.nwleague.service;
 
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
 
/**
 * Location: service
 * Created: IceSqueez
 * Date: 24.12.2013
 * Time: 15:40
 */
 
public class Service implements Runnable {
    private final int port;
 
    public Service(int port) {
        this.port = port;
    }
 
    @Override
    public void run() {
        EventLoopGroup eventWork = new NioEventLoopGroup();
        EventLoopGroup eventBoss = new NioEventLoopGroup();
        try {
            ServerBootstrap bootstrap = new ServerBootstrap()
                    .group(eventBoss, eventWork)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ServiceInitializer(this.port));
            bootstrap.bind(this.port).sync().channel().closeFuture().sync();
        } catch (InterruptedException ignored) {
        } finally {
            eventBoss.shutdownGracefully();
            eventWork.shutdownGracefully();
        }
    }
}

package ru.nwleague.service;
 
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
 
/**
 * Location: service
 * Created: IceSqueez
 * Date: 24.12.2013
 * Time: 15:44
 */
 
public class ServiceInitializer extends ChannelInitializer<SocketChannel> {
    private final int port;
 
    public ServiceInitializer(int port) {
        this.port = port;
    }
 
    @Override
    protected void initChannel(SocketChannel channel) throws Exception {
        ChannelPipeline pipeline = channel.pipeline();
        pipeline.addLast("framer", new DelimiterBasedFrameDecoder(this.port, Delimiters.lineDelimiter()));
        pipeline.addLast("decoder", new StringDecoder());
        pipeline.addLast("encoder", new StringEncoder());
        pipeline.addLast("handler", new ServiceHandler());
    }
}

package ru.nwleague.service;
 
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundMessageHandlerAdapter;
import ru.nwleague.Boot;
import ru.nwleague.data.Client;
import ru.nwleague.data.Commands;
import ru.nwleague.struct.MessageEnum;
 
/**
 * Location: service
 * Created: IceSqueez
 * Date: 24.12.2013
 * Time: 15:45
 */
 
public class ServiceHandler extends ChannelInboundMessageHandlerAdapter<String> {
private ChannelGroup channel = new DefaultChannelGroup();
 
    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        channel.add(ctx.channel()); // Клиент пришел
    }
 
    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        channel.remove(ctx.channel());//Клиент ушел
    }
 
    @Override
    public void messageReceived(final ChannelHandlerContext channelHandlerContext, String message) throws Exception {
        System.out.pringln(message);
    }
}