package io.netty.example.discard;import io.netty.buffer.ByteBuf;import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;/*** Handles a server-side channel.*/
public class DiscardServerHandler extends ChannelInboundHandlerAdapter { // (1)
@Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) { // (2)// Discard the received data silently.((ByteBuf) msg).release(); // (3)
    }@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { // (4)// Close the connection when an exception is raised.
        cause.printStackTrace();ctx.close();}
}

@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {try {// Do something with msg} finally {ReferenceCountUtil.release(msg);}
}

package io.netty.example.discard;import io.netty.bootstrap.ServerBootstrap;import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;/*** Discards any incoming data.*/
public class DiscardServer {private int port;public DiscardServer(int port) {this.port = port;}public void run() throws Exception {EventLoopGroup bossGroup = new NioEventLoopGroup(); // (1)EventLoopGroup workerGroup = new NioEventLoopGroup();try {ServerBootstrap b = new ServerBootstrap(); // (2)
            b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class) // (3).childHandler(new ChannelInitializer<SocketChannel>() { // (4)
                 @Overridepublic void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new DiscardServerHandler());}}).option(ChannelOption.SO_BACKLOG, 128)          // (5).childOption(ChannelOption.SO_KEEPALIVE, true); // (6)// Bind and start to accept incoming connections.ChannelFuture f = b.bind(port).sync(); // (7)// Wait until the server socket is closed.// In this example, this does not happen, but you can do that to gracefully// shut down your server.
            f.channel().closeFuture().sync();} finally {workerGroup.shutdownGracefully();bossGroup.shutdownGracefully();}}public static void main(String[] args) throws Exception {int port;if (args.length > 0) {port = Integer.parseInt(args[0]);} else {port = 8080;}new DiscardServer(port).run();}
}

@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {ByteBuf in = (ByteBuf) msg;try {while (in.isReadable()) { // (1)System.out.print((char) in.readByte());System.out.flush();}} finally {ReferenceCountUtil.release(msg); // (2)
    }
}

 @Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) {ctx.write(msg); // (1)ctx.flush(); // (2)}

package io.netty.example.time;public class TimeServerHandler extends ChannelInboundHandlerAdapter {@Overridepublic void channelActive(final ChannelHandlerContext ctx) { // (1)final ByteBuf time = ctx.alloc().buffer(4); // (2)time.writeInt((int) (System.currentTimeMillis() / 1000L + 2208988800L));final ChannelFuture f = ctx.writeAndFlush(time); // (3)f.addListener(new ChannelFutureListener() {@Overridepublic void operationComplete(ChannelFuture future) {assert f == future;ctx.close();}}); // (4)
    }@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {cause.printStackTrace();ctx.close();}
}

Channel ch = ...;
ch.writeAndFlush(message);
ch.close();

f.addListener(ChannelFutureListener.CLOSE);

$ rdate -o <port> -p <host>

package io.netty.example.time;public class TimeClient {public static void main(String[] args) throws Exception {String host = args[0];int port = Integer.parseInt(args[1]);EventLoopGroup workerGroup = new NioEventLoopGroup();try {Bootstrap b = new Bootstrap(); // (1)b.group(workerGroup); // (2)b.channel(NioSocketChannel.class); // (3)b.option(ChannelOption.SO_KEEPALIVE, true); // (4)b.handler(new ChannelInitializer<SocketChannel>() {@Overridepublic void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new TimeClientHandler());}});// Start the client.ChannelFuture f = b.connect(host, port).sync(); // (5)// Wait until the connection is closed.
            f.channel().closeFuture().sync();} finally {workerGroup.shutdownGracefully();}}
}

package io.netty.example.time;import java.util.Date;public class TimeClientHandler extends ChannelInboundHandlerAdapter {@Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) {ByteBuf m = (ByteBuf) msg; // (1)try {long currentTimeMillis = (m.readUnsignedInt() - 2208988800L) * 1000L;System.out.println(new Date(currentTimeMillis));ctx.close();} finally {m.release();}}@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {cause.printStackTrace();ctx.close();}
}